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More than three decades after a 737 ripped open over Hawaii and stunned the flying public with the dangers of human error in aircraft maintenance, the aviation industry is still challenged to contain that risk and keep crews and passengers safe in the air.

The toughest hurdle is persuading aircraft operators, manufacturers, vendors and their maintenance technicians to comply with procedures.

The industry has made great progress since April 28, 1988, when the top of an Aloha Airlines Boeing 737’s fuselage tore free at 24,000 feet. A flight attendant vanished and 94 others on board were terrified, with 65 injured. Images of them surrounded in the landed jet’s front cabin by little more than moist island air and shredded metal shocked much of the world. It was vivid proof of the hazards in pushing aircraft beyond the eye’s and brain’s abilities to keep them flying safely.

The fuselage blew because a lap joint failed, then a lot of minor cracks around rivet heads opened up like a zipper. The NTSB said Aloha Airlines maintenance program failed to detect significant disbonding and fatigue damage that led to that. It found “difficult and tedious” 737 inspection procedures had “physical, physiological and psychological limitations.”

The Threat Persists

Spurred by the flying public and the U.S. Congress, regulators and the industry launched an effort to identify maintenance-error hazards, research their causes, find ways to reduce risks and field effective mitigation measures. Over three decades, inspection procedures and techniques were improved and maintenance standards made stricter. Yet incidents and accidents show repeatedly that the threat persists, particularly the biggest one: failure to follow procedures.

Most maintenance tasks have written procedures that they say must be followed and are intended to produce the same result every time. “However, the incidence of failure-to-follow-procedures events continues to be a major issue in aviation maintenance,” three researchers reported in 2017.

Colin G. Drury and Catherine Drury Barnes of Applied Ergonomics Group and Michelle R. Bryant of the FAA’s Civil Aerospace Medical Institute had been tasked in 2015 with examining primary and contributing factors of failing to follow procedures and then developing mitigation strategies. Despite 30 years of research into procedural compliance, their report noted, “these challenges and recommendations have not changed a great deal in that time period.”

In 2019, FAA chief maintenance human factors advisor Bill Johnson spoke with executives of large U.S. airlines. “Without exception,” Johnson, said, they told him “procedural non-compliance is the unanimous No. 1 contributing factor” for maintenance-error events.” (Now retired from the FAA, Johnson is principal scientist at drbillj.com.)

“Even as we speak, there are hundreds of mechanics probably deviating from procedures,” said Robert Baron, president and chief consultant of The Aviation Consulting Group. He specializes in human factors and other safety training and issues, working with hundreds of aviation organizations around the world. “Fortunately, it’s a safe system. There are backups, redundancy, cross-checking and different types of oversight. But when something slips through, that could be potentially catastrophic.”

Consequences of Rule-Breaking

Baron’s comment pointed toward an underlying reason for persistent procedural non-compliance, which Gordon Dupont explains with an everyday analogy. As a Transport Canada safety officer in the 1990s, Dupont crafted the noteworthy “Dirty Dozen” list of 12 human factors that can degrade your ability to perform effectively and safely and lead to maintenance errors. He is the retired CEO of System Safety Services in Richmond, British Columbia.

“What’s the most common rule broken every day all around the world? The speed limit,” Dupont has said. “The average driver will go between 5 and 10 mph over the speed limit unless the weather is bad, there is a police officer close by” or some other condition slows the driver down. “So why do we do it? The answer is very simple. We foresee no negative consequences in breaking the speed limit and the positive consequence of getting to our destination sooner serves to justify the rule-breaking. Rule-breaking at work goes along the same lines.”

Overall, maintenance errors can appear to be a small problem. Boeing’s analysis has long put maintenance as a primary cause of just 3 to 4 percent of hull-loss accidents and a contributing cause of about 10 percent. By comparison, flight crew actions are cited as a primary cause in more than 60 percent.

Analysis by the International Air Transport Association (IATA) found that “maintenance operations” were a latent condition in 21 percent of 2020’s airline accidents and “maintenance operations: SOPs and checking” was a latent condition in 13 percent. IATA’s safety analysts define a latent condition as one that is present in the system before an accident that is made evident by triggering factors (which often relate to deficiencies in organizational processes and procedures).

In 2020’s accidents, IATA said, maintenance was a threat in 21 percent. It defines a threat as an event or error that occurs outside the pilots’ influence but requires their attention and management to maintain safety margins.

From 2016 to 2020, IATA found, maintenance operations were a latent condition in 12 percent of accidents. For maintenance operations: SOPs and checking, the number was 11 percent. Maintenance was a threat in 14 percent over that time. From 2011 to 2015, maintenance operations and maintenance operations: SOPs and checking each were latent conditions in 7 percent of accidents and maintenance was a threat in 10 percent.

“We’re stalled,” said John Goglia, a retired airline mechanic and former U.S. National Transportation Safety Board (NTSB) member who has been a driving force in addressing maintenance human factors issues. “We need to look at our history and do something different.”

A Problem Lies in Wait

One recent incident illustrates how the failure to follow procedures can create a problem that lies in wait.

On Oct. 23, 2020, a Jetstar Airways Airbus A320-232 was taking off from Brisbane, Australia. As the IAE V2527-A5 engines spooled up, the pilots noticed a vibration and “popping” noise that rapidly increased in frequency and volume. They rejected the takeoff at 30 knots. Stall and temperature-exceedance warnings appeared for the No. 2 engine. They learned that passengers had reported flames coming from the right engine, as had the tower controller and a following flight crew. Recorded data indicated it had surged.

An on-wing borescope inspection found out-of-limit damage to the right engine’s high-pressure compressor (HPC) consistent with foreign object strikes. A teardown inspection confirmed substantial HPC damage, including a broken stage 5 blade and one stage 6 vane, four stage 7 blades and one stage 8 blade that were missing. A screwdriver tip was found between the combustion liner and engine case, burnt, discolored and eroded from heat and mechanical damage.

The aircraft had been parked for four months. The return-to-service work included lubrication of the low-pressure compressor bleed valve mechanism. Procedures “contained specific highlighted caution notes regarding the loss of any screws or other loose objects down the bleed duct,” the Australian Transport Safety Bureau said in its Aug. 16, 2021 incident report. “The notes highlighted that lost articles would progress to the HPC and break valves and vanes.”

The bleed valve was lubricated 112 flight cycles prior to the Oct. 23 engine surge, the ATSB said.

Helicopter Crew Gets Lucky

Sometimes negative consequences of procedural non-compliance are quickly apparent.

On June 1, 2020, the crew of a Northern HeliCopter AS365-N3 were alerted for a rescue mission from their St. Peter-Ording Airfield base, about 85 miles (138 kilometers) northwest of Hamburg on Germany’s North Sea coast. It would be the day’s second flight. The pilots used an approved “scramble” takeoff procedure that did not include a flight control hydraulic check.

The copilot increased thrust. The helicopter lifted to a hover, then immediately pitched up. The copilot lowered the collective. The tail struck the ground and the main landing gear touched down hard. No one was injured. The helicopter was slightly damaged.

The pilots determined that forward and backward cyclic inputs had no effect on the rotor disk. They shut down on the runway. Back in the hangar, they found that the left actuator was not connected to the swashplate that redirects the main rotor blades. Its fastener was missing. They found the bolt, two washers and one Nylon stop crown nut on the gear box compartment below. They did not find a loose cotter pin or parts of one.

Through mid-May, a contractor had performed substantial maintenance on the helicopter, including a main gearbox leak repair that required the left actuator’s removal. A post-maintenance check flight was done. The repair was assigned to experienced mechanics and was checked by an experienced inspector. “However, that check had been signed a few days after the occurrence,” said the Federal Bureau of Aircraft Accident Investigation (with the German acronym BFU), which investigated. The mechanics, inspector and maintenance pilot told the BFU in written statements that the actuator’s screw fitting was properly installed and the cotter pin was positioned and visually checked several times before the helicopter was returned to the operator.

Those maintenance personnel “were certainly aware of the importance of the flight controls and were certainly familiar with different types of screw lockings,” the BFU said in its report.

The BFU concluded the incident was most likely caused by mechanics using a worn Nylon stop crown nut on the actuator-to-swashplate bolt, applying insufficient torque to that nut and not installing a cotter pin on it.

The BFU also concluded the inspector did not sufficiently check the mechanics’ work and that two other mechanics failed to check the actuator connection as required by a 10-flight-hour/seven-day-inspection performed the day before the incident.

“It was just luck that during the occurrence — total loss of control — only the tail skid of the helicopter was damaged and more severe damage or even injuries to persons did not occur,” the BFU report observed. Between its return from maintenance and the loss of control, the helicopter flew for a total of 8:46 flight hours.

BA 787-8 Case Study

Another recent maintenance error made itself known much faster.

On June 21, 2021, a British Airways Boeing 787-8 was being loaded at London’s Heathrow Airport for a cargo flight. Three mechanics were tasked with clearing status messages about a nose landing gear solenoid valve. The procedure required cycling the landing gear with hydraulic power applied to the aircraft. To prevent the gear from retracting, the procedure required pins to be inserted in the main and nose gear downlocks.

The lead mechanic, in the cockpit captain’s seat preparing for the job, told the other mechanics to place pins in the downlocks and ensure the four people loading cargo were clear of the aircraft. At the nose gear, the first mechanic could not reach the locking pin hole. He pointed to the hole’s location and the second mechanic fitted the pin, which like the others had red and yellow flags attached. At the right main gear, the first mechanic used portable steps to fit the pin. He repeated that on the left gear.

The first mechanic returned to the cockpit to tell the lead the pins had been fitted. The two mechanics then returned to the nose gear and plugged a communications headset into the nose gear bay port. The lead requested confirmation again that the pins were in place. The first mechanic said they were.

The lead mechanic applied hydraulic power. Before moving the gear lever, he requested final confirmation from the first mechanic that the pins were in place and the cargo team was clear. This mechanic again visually checked that he could see the warning flags for each gear pin. He also checked that no feet were visible to indicate the load team was clear. He then confirmed this to the lead.

In the cockpit, the lead selected the gear lever to up. The nose gear retracted and the nose fell to the ground.

The worker on the pallet loader under the starboard forward cargo door was slightly injured as that door moved down when the fuselage dropped. The copilot, sitting in the cockpit, received a minor injury.

The nose crushed a ground power unit’s articulated cable arm. The lower forward fuselage and nose gear doors were damaged, as were both engine cowlings (which also struck the ground). Door 2L struck the stairs positioned at its opening when the nose fell and was severely damaged.

When the recovery operation lifted the nose, the nose gear was examined and the downlock pin was found fitted not in its hole but in the apex pin bore next to it.

No Silver Bullet

Researchers talk of errors of omission (such as failing to install O-ring seals on turbine engine chip detectors) and of commission (such as using incorrect fasteners to install a cockpit windshield). There are timing errors (performing a task at the wrong time or in the wrong order) and precision errors (such as using the wrong setting on a torque wrench).

They also talk of perception errors (“I didn’t see that”) and slips (“I didn’t mean to do that”), as well as wrong assumptions (“I assumed we returned to Stand 513, where the aircraft’s integrated drive generator oil levels had to be checked, but we went to Stand 517”). There is technical misunderstanding (“I tried to replace the landing gear hydraulic-retract actuator, but I didn’t understand what I had to do”).

One of the most common maintenance errors involves a mechanic forgetting to do a task planned for completion before a job is closed out, such as removing an engine thrust-reverser lockout pin after investigating an engine bleed-air issue.

All of the above can involve failure to follow procedures, since many procedures are aimed at heading off such errors. Dupont classifies violations in three main ways.

In a situational violation, he says, a mechanic concludes a job can’t be completed without violating a procedure. This is often related to time pressures. It may not be repeated. The situation seems to justify the violation.

An exceptional violation occurs when there appears to be no other way to accomplish the task. Dupont offers the example of a manual calling for three people to be used at all times when moving an aircraft. If a mechanic is out sick, crewmates may decide to push the aircraft carefully using the only two people available.

A routine violation happens when a mechanic believes there is a better way to complete a task and sees no negative consequences to the ad hoc procedure, Dupont explains. It may start as a situational violation, but over time the informal procedure may become a norm.

If the mechanic’s organization condones or tolerates the violation, it can move into a fourth class: the organizational violation. A classic example, Dupont says, is May 25, 1979’s crash of American Airlines Flight 191. The links leading to the accident, which killed all 271 on the plane and two on the ground, included failures by the jet’s manufacturer, the FAA and the airline’s management, engineering and maintenance departments, as well as the mechanics.

Safety proponents are refining efforts to reduce procedural non-compliance. The FAA has fielded a free, 45-minute training course, “The Buck Stops with Me,” aimed at “creating champions for rules-following,” Johnson said. Several researchers are pursuing efforts to apply the safety gains of line-oriented safety audits on the flight deck to maintenance operations. Expanding requirements for operators to set up safety management systems may aid the effort by promoting the acceptance and use of human factors analysis to maintenance.

“There is no silver bullet for any of this,” Baron said. “It’s all about awareness.”

Finding and tracking hard-to-find aircraft parts — and accessing support services to help with the acquisition and stocking process — is a constant challenge for the global MRO industry. COVID-19 has only made the situation worse, by slowing down supply chains and the manufacturing/distribution of spare parts.

The good news: Web-based information technology (IT) systems are helping to ease this problem for MROs through online parts locating, purchasing, tracking, and deliveries. Here is a look at some of the players in this market, and how they are performing for clients during the current supply chain crunch.

Four Key Players

There are a number of IT-based companies offering parts locating, tracking and sales on the web. Here are four of them that responded to Aviation Maintenance’s requests for interviews.

Farsound offers a vast range of expendable parts across a multitude of company search engines. The company also provides purchasing/delivery services to MROs ranging from consignment, kitting, Kanban and ad hoc orders. All orders can be placed by Spec2000, Aeroexchange or via email.

“Having consignment at the customers location saves time with shipping,” said Lee Kelsey, Farsound group sales director. “Parts are readily available, even if there are fluctuations in demand.”

“Our kitting services save time for the operators and stores personnel,” he added. “They don’t have to book individual items in their store or transact them out. The kits are built to go straight to the operator on the shop floor, saving a lot of time and foot fall.”

Farsound is developing an e-commerce platform, which is scheduled to go live in February 2022. Customers will be able to login to make orders, review their order histories, track items shipped and check on Farsound’s ‘live stock’.

ILS and its online ILS Marketplace makes it easy for MROs to search through its inventory of one billion-plus parts, and access the company’s global services aimed at commercial, general aviation/business aviation and defense/military customers. ILS also provides direct supply chain integration, a wide array of market intelligence solutions and real-time updates on parts availability and prices, even during the current COVID-induced supply chain crunch.

“While the pandemic did not impact our ability to source and/or locate parts, we have continued to enhance our products and services,” said Eric-Jan (EJ) Schmidt, ILS’ head of Global Marketing, “These enhancements include products and services to make our customers more efficient — such as our ILS Bridge providing real-time ILS Marketplace integration for Quantum/CORRIDOR and other ERP customers — and to assist them in improving sales/purchasing productivity at a time when team sizes are smaller, using either our ILS SalesEdge or ILS BuyersEdge.” ILS also gives its clients more ways to access supply chain market intelligence through its expanded FMV Intelligence, Aviation Data Warehouse access and large IPC Analyzer portfolio (airframes as well as engines) to help MROs and other customers make better buying and selling decisions.

“During COVID, we saw an increase in customer demand for ‘parts sourcing optionality’ — i.e. if I cannot afford and/or timely source a new part/component, what USM or PMA alternatives would be available?” Schmidt noted. “Consequently ILS has developed expanded Intelligence for USM/PMA parts, benefitting MROs and other suppliers with better insights into available demand, supply, and quality levels.”

STS Component Solutions provides a host of IT-driven supply chain solutions to airlines and MROs worldwide. These solutions include OEM parts distribution, repair management, AOG services, and warranty administration inventory valuation/analysis, as well as offering “Hard to Find” sourcing services. The company also provides integrated solutions that include reliability analysis and tracking, 3D printing, engineering services, and staffing solutions.

“STS Component Solutions provides cost-driven programs focused on the proper stocking and strategic placement of inventory, either on-site or geographically situated to eliminate the delays associated with parts shortage,” said Tom Covella, group president of STS Component Solutions. “Additionally, our engineering services people are able to provide DER (Designated Engineering Representations) services in a very expedited manner eliminating potential delays from OEM approvals.”

For those MROs needing more than parts and services, GlobalAir.com offers its customers access to an aviation business database with more than 550 maintenance, repair and operation companies included. It also contains a database of virtually every FBO in the United States. Many of these companies are partners or sponsors of GlobalAir.com.

According to Josh Coffman, this company’s vice president of Content and SEO, “GlobalAir.com is a one-stop shop to find everything you need from an interior designer, an aircraft painter or to buy a new or used aircraft. The aviation community has counted on our site for a quarter of a century to find reputable MROs.”

COVID’s Impact

Given the global pandemic’s two-year stranglehold on the global supply chain, it made sense for Aviation Maintenance magazine to ask these companies about COVID’s impact on their businesses — and their ability to source parts and services for clients.

Not surprisingly, the pandemic has gummed up the works.

At STS Component Solutions, “we have seen COVID impact delivery dates and lead-times throughout the industry,” said Covella. “Lead times are being extended as the global market is being challenged by both material availability and labor resources. This is a new challenge that our industry is now facing, and we must adjust accordingly. At STS, we are constantly adjusting our inventory forecasting tools to accommodate for these new extended lead times, plus additional tools and KPIs to track ‘on time’ deliveries.”

Locating scarce aircraft parts during COVID has not been easy for MROs and their suppliers. “The pandemic increased competition, forcing more MROs and other suppliers to find ways to lower the probability of supply chain related challenges,” ILS’ Schmidt said.

To help MROs cope, ILS came up with a number of creative options. For example, “we provided them with ‘parts optionality’ insights to help them work through the problem,” said Schmidt. “Meanwhile, many customers experienced talent shortages and a need to make smarter decisions faster with less staff, increasing their demand for intelligence that we included in our various solutions. These solutions can range from as simple as one-click on-demand requests for information, to more comprehensive AI/ML and RPA (Robot Process Automation) powered solutions that intelligently help prioritize responses to RFQs.”

As for GlobalAir.com’s take on COVID-19’s impact on supply chains? “More business is being done remotely,” Coffman replied. “More private aircraft are being acquired overseas and then brought here for maintenance. We are seeing some of our strongest traffic in our site’s history. Now more than ever, aviation businesses need a strong online presence, and that’s something that’s been in the GlobalAir.com DNA since the mid-1990s.”

Offsetting the Shortages

One reason why supply chains dried up during the pandemic was due to customers cancelling their orders for parts, in an understandable bid to conserve cash. But this wasn’t the case at Farsound. “During the global COVID pandemic we made a conscious decision not to cancel purchase orders on our main manufacturers and suppliers,” said Kelsey. “We knew there would be a bounceback within the market and it would be better to have additional stock around us. We knew that turnaround time and service will be key in the uptick in the market.”

“Holding stock of the right product is essential, providing a quick turnaround for MRO orders and ensuring that there are no issues,” he observed. “The fact that we did this allows our MRO customers to focus on other issues of importance.”

“With STS Component Solutions’ inventory forecasting tools, ‘Smart Stock’ inventory programs, exchange programs and AOG devices we are able to address some of the challenges the industry is currently facing,” added Covella. “Our ability to provide ‘Additive Manufacturing’ (3D printing) is also able to supplement current shortages in the global supply chain crisis.”

Making Things Better

As MROs come to rely more on IT-driven parts locating, tracking, and delivery, it only makes sense for them to know what the industry has in mind to improve and speed up the process.

Here’s what these four players told us.

For Farsound, achieving success in easing MROs’ parts procurement means becoming part of their day-to-day locating and tracking process. To this end, “Farsound is trying to be fully integrated with our customers, building long term partnerships so we have an even better understanding of their requirements,” said Kelsey. “This includes offering an e-commerce platform where they can see what we see in our system, providing MROs with total transparency. We have also introduced engine-side vending machines at their locations. These machines allows parts for specific engines to be stored and delivered as needed on site, again reducing time.”

Meanwhile, ILS is committed to expanding its range of products and services for MROs in various ways. “Consistent with our vision, we will offer more enhanced decision analytics to MROs with data-driven intelligence, plus additional advanced aviation intelligence using AI/ML technology and other data sources,” Schmidt said. “We will also drive more collaboration and compliance among marketplace customers to provide a trusted buying and selling experience, plus expand our ERP and add transaction integration with their systems as well as our marketplace, evolving ILS into a supply chain hub.”

STS Component Solutions is also seeking ways to improve parts location, tracking and delivery to its MRO customers. To this end, “we are constantly changing and adapting our products and services to address the current challenges,” said Covella. “We have spent many hours refining our data analytics and forecasting tools to make sure we have current market and demand data. Additionally, we have established integrated solution teams on site at our customers to focus on the largest ‘pain points’ they are currently experiencing.”

“Our ability to establish on-site teams and integrate with our customers will lead to improved support levels, reduced parts shortages, improved reliability and higher dispatch reliability,” he noted. “Right now, STS Project Teams are evaluating internal processes and identifying bottlenecks and cost savings opportunity by establishing kitting programs, exchange programs and strategic stocking programs.”

Finally, GlobalAir.com is reviewing its portfolio of services, seeking ways and opportunities to help MROs. “From direct advertising to digital marketing, we offer an array of options to help aviation businesses fly above their competition — especially in these turbulent times,” said Coffman.

The bottom line; IT-driven parts locating, tracking, and delivery companies are pulling out the stops to address the parts supply chain crunch for MROs. Although they can’t solve the supply chain issue on their own, these companies are doing what they can to make the situation better.

The fast-paced digital transformation of the aviation industry, coupled with the emergence of new propulsion technologies is challenging the aviation maintenance training industry as regulators drag progress into the future of aviation maintenance.

While colleges, engine and airframe manufacturers and MROs such as Lufthansa Technik Training (LTT) and Air France Industries KLM Engineering & Maintenance (AFIKLM E&M) are adopting new training technologies such as Virtual Reality (VR) and Augmented Reality (AR), the critical aviation maintenance school ecosystem is being held back despite the fact FAA has been congressionally mandated to reform Part 147 training. The mandate passed last December, part of a decades-long effort to bring maintenance training into the 21st Century, but has yet to be implemented.

Brave New World

Companies are adopting new technologies for which trainees must prepare.

For instance, Safran contracted with Librestream to adopt its Onsight augmented reality platform for remote customer support. Safran Helicopter Engines first launched a remote assistance service called Expert Link in early 2018. The instant expert connection for technical diagnostics and preventive maintenance tasks through a live video and audio feed accounted over 1,000 visual assistance calls covering 40 countries per year.

Jasoren is also offering remote maintenance using augmented reality to provide remote workers with real-time, AR-based assistance through video calls with experts, shortening maintenance downtime while reducing travel expenses and errors, said the company. In training, it is more engaging and interactive with real-time remote guidance by experts, increasing the effectiveness of onboarding and training sessions

Similarly, aircraft painters with the Air Force 588th Aircraft Maintenance Support Squadron Corrosion Control shop, are using a virtual reality paint training allowing hands-on time in a controlled environment simulator to reinforce the skills learned in class.

Many have already deployed virtual maintenance trainers (VMTs) offering students 3D training scenarios through which to learn aircraft systems and troubleshooting. For instance, Airbus uses a VR headset, touchpads and infrared cameras enabling inspection and repair within the VR environment.

FlightSafety International (FSI) has Virtual Aircraft, an immersive 3D learning experience assisting students and instructors in exploring the aircraft as if they were out on the flight line. These true-to-life interactions with the aircraft’s various components happen in real time. FSI indicated the technology results in higher retention, an increase in transferable skills and competency.

FSI also has Virtual Engine Trainers, a real-time, interactive/animated models of Pratt & Whitney engines allowing manipulation of the engine and inner workings in any position or system grouping. Students can even change parts.

“X-ray and move functionality further enable students to view dynamic cross-sections into nearly every engine part,” FSI wrote. “Borescope inspection training is also available with typical wear and tear simulation throughout the engine, allowing students to practice damage assessment and engine dispatchability. EASA has approved Virtual Engine Training as a method of assessment in up to 50 percent of practical engine training.”

Through its LiveLearning delivery method, FSI offers clients a hybrid classroom – both in-center and remote, according to SVP Operations Brian Moore. “This allows for the same collaboration and discussion you would have in a traditional in-center course,” he told Aviation Maintenance.

Industry Wants High Tech Training Shifted to Training Environment

Industry has spoken with a single voice it wants better prepared aviation maintenance technicians. It signaled a requirement for super technicians able to work across avionics, airframe and engine disciplines. Finally, there is growing concern restrictive curricula will hamper integration of new propulsion technologies and advanced air mobility.

Aviation maintenance schools have been so hamstrung by highly prescriptive, antiquated training regulations that they spent almost two decades trying to change within the FAA. In frustration, Aviation Technical Education Council members developed modern curricula that would achieve the same competency outcomes and enable the adoption of new and innovative technologies. Congress used it to mandate the long-overdue FAA changes. It also allows for the adoption of new programming to accommodate emerging technologies and the expansion of the aviation maintenance training industry footprint to satellite facilities such as high schools and community colleges, necessary to address the mechanic shortage.

For instance, big data analysis and predictive maintenance has never been part of the FAA required curriculum and won’t be part of the FAA mechanic certification standards (at least in the short term) when they are published. But, Crystal Maguire, ATEC executive director, said schools will have the flexibility to add content to their coursework once the new rule is published.

“We need to reform Part 147 regulations in order to give more academic freedom to teach students,” Joel English, executive vice president at the Aviation Institute of Maintenance said. “There is evidence that the FAA is listening so schools are preparing for the day they are able to apply professional judgement and academic flexibility to our programs, which is severely limited today.”

The system is based on an hourly metric rather than proven competency but even that is complex.

“Though there is only one set of guidelines for part 147 schools, the individual Principal Maintenance Inspectors (PMIs) at the local FAA offices often interpret these rules differently. Though we have one standard curriculum taught at all 14 of our campuses, PMIs often interpret FAA rules differently and force our instructors to change the standard curriculum to fit a PMI’s own individual opinion. That means that we must adapt the standard curriculum differently at our different locations to meet the desires of the individual inspector. The FAA gives us a standard, we build one curriculum to meet that standard across the country, but the individual field officers make us change to meet their interpretation of the standard! It’s a challenge that will be overcome when the FAA allows us to apply our own professional judgement to the curriculum development process to accommodate the needs of the employers who hire graduates.

“Students will still be expected to attain the same outcome – passing the FAA certification exams to become a certificated A&P mechanic,” he continued. “But schools will have the ability to focus on what employers are requesting, and re-orient the instruction with some degree of academic freedom.”

There is more flexibility at the university level, English said because they go beyond the 1900-hour prescription and teach additional content such as VR and other innovations. “The FAA neither regulates nor cares about this material,” he said.

To increase student preparedness, AIM includes an additional Capstone course, which is beyond the FAA’s 1,900 hours, and includes an adaptive learning platform and VR within that instruction.

Covid Accelerates Innovation

“Covid definitely changed our training methods and sped up everything,” Zonda Feulner, Pratt & Whitney director of customer training, said. “We became more agile and creative. We quickly adapted our Engine Explorer Application from touch screen to using a mouse for remote learning and so we could pivot to AR and VR as needed because that is where a lot of our customers are going.”

FSI worked to get distance learning approved by regulatory authorities, resulting in increased efficiency and cost savings as such instruction moved online.

Aviation Maintenance previously reported L3Harris sees a 20 percent reduction in maintenance training costs with AR/VR/MR (mixed reality) training. More importantly for the aviation mechanic shortage, L3Harris increased student throughput fourfold with virtual training and projects it can achieve 30- to 50-percent reduction in training times with further enhancements to its learning management system.

Boeing also demonstrated the value of the technology with the same outcomes as working actual aircraft. Finally, GE found task performance time declined 10 percent and increased job satisfaction by 85 percent.

The Evolution of AV MX Training

As aircraft and aviation maintenance professionals evolved so too has aviation maintenance training, said FlightSafety International SVP Operations Brian Moore.

“Our work with OEMs has allowed us to remain on the cutting edge of advances in aircraft,” he said. “We use a combination of real engines and components, and immersive training tools like our virtual engine and virtual walk-around to ensure each technician is highly skilled and able to troubleshoot effectively.”

The Covid changes are the latest in the evolution of maintenance training beyond classroom instruction, according to AFIKLM E&M’s Wanda Manoth-Niemoller, commercial development manager, who noted AR use-cases are built in cooperation/partnership with other parties. Similarly, the company is studying cases incorporating combinations of Artificial Intelligence (AI) and big data in operations, as well as remote support.

AI is already the pilot training realm which can be applied in aviation maintenance training. The idea is to give students immediate data-based feedback on performance and identify areas where continued work is needed so students can master that work to ultimately gain competency. This immediate feedback is expected to improve competency and reduce training time. It is already using to track whether a trainee picks up the wrong tool and how often.

“We started off with our maintenance simulation training device on a laptop or desktop, with which we are able to save up to 50% training time on practical on the actual aircraft,” Manoth-Niemoller told Aviation Maintenance. “With part 145 courses we are able to do 100% simulation. After the desktop simulation, we introduced VR in both part 145 as well as part 147 courses. The latest addition is AR, which we currently use to explain system behavior in the 777 and to do 100% of the practical for the engines on the 777 and the 787 in AR. The first business cases are now in development to introduce AR in the MRO operation. Also, in VR we are still developing such things as engine run up 2.0 and 360 VR which are made in cooperation with the schools, to use in part 66 training.”

“In general, ours has evolved by inserting new technology into instructor-led, hands-on training,” Feulner told Aviation Maintenance. “That goes hand in hand as engineering progressed. We started six years ago by creating our Engine Explorer Application for the GTF, V2500, and the JSF, displaying a 3D model students can manipulate to isolate different systems and search for different parts. This enhances the classroom portion and increases class participation. Once we created that foundation and built the 3D models, we switched over to VR training to test students. It allowed us to provide the support items, such as animation on how to do a specific task if they are having a tough time.”

Supplementing Online Training

Not all training can be done online, however.

“I believe that nearly half of the part 147 program could be taught effectively online, but I have found that my students prefer face-to-face instruction,” said English. “I’ve created a wide range of online simulators within many different academic situations, and my students want the real thing. We recognize students who want to become aircraft mechanics generally want to be in a hangar, with tools and equipment, alongside classmates and a seasoned instructor.

“I think that augmented and virtual realities are probably best for theoretical understanding of the anatomy of aircraft and for general familiarity of aircraft systems,” said English. “As technologies get better, I’m sure there will be some manual processes that can be virtualized, but I believe that AR and VR teach the mind, not necessarily the body. Something important happens when a student strikes an arc in a welding booth and not only sees the machinery respond but also smells the fumes, feels the heat and registers the resistance of the flame change when it touches metal that a computer cannot yet tell them; when they struggle to push an aircraft onto a scale and feel the bounce of the tires moving into position, they are learning something that an online simulation won’t tell them. I believe becoming an aircraft mechanic is a process of tactile engagement as much as theoretical learning. The subtleties of work in an aircraft hangar and the physical feedback that tools and machines give the budding mechanic just can’t be efficiently replicated on an iPhone or in an Oculus headset. That simple, satisfying ring of a ratchet, singing like a stainless-steel cricket in one’s hand, speaks to a mechanic. Entering a username and trying to remember a password is not the mechanic’s language.”

Even so, there is no question online learning is here to stay.

“We see Online Distance Learning (ODL) as a game changer in future education,” Lufthansa Technik Training head of sales, key account management & marketing Harald Schween told Aviation Maintenance. “ODL has become an important part of our maintenance training portfolio. And, beyond online maintenance training, we expect blended-learning methodologies to become more relevant in the industry such as a combination of modern e-learning media with classroom and online training sessions.”

For LTT, it’s all about aligning its methods and tools to the requirements of customers. “We are convinced that VR, beside other digital solutions, will play a some role in future maintenance training,” said Schween. “With VR we can give the trainees a better understanding of the complexity of an aircraft and can give them the chance to (virtually) touch components of an airplane. Through VR technologies we can show how the aircraft looks and we may use VR to complement deeper level maintenance training. Furthermore, we may have the possibility to bring practical elements into the classroom virtually to decrease the amount of physical practical training days at the aircraft.”

Schween sees little progress at EASA to adopt new learning methods into regulations (Part-147, Part-66). “Hence, there are no formal benefits, such as credits to a EASA Part-66 CAT A or B program, through the application of eLearning, digital media or VR. On the other hand, the regulators have recently incorporated distance learning methodologies, such as video conferencing, into maintenance training requirements. This has been done in a very flexible and industry-oriented manner. We strongly believe this positive experience and fruitful collaboration between industry partners and the regulators will be continued for the implementation of digital tools and solutions in the future.

“The transition from ‘traditional’ classroom training to new learning methodologies changes teaching significantly,” he continued. “For example, instead of instructor-led lectures, the instructor becomes more a coach, guiding them throughout their learning path and experience. Instructors and trainees have to deal with new tools and methodologies such as handling of digital media and tools within a modern blended learning environment and we strongly believe in the benefit of ‘blending’ traditional and digital learning methodologies.”

Much to be Done

Even as industry continues to adopt new training technologies, the fact remains there is much to be done to bring the entire aviation maintenance training ecosystem to the same level. With part 147 reform in the United States and similar efforts on the international front, there will come a time when that happens, but it can’t come fast enough given the speed with which different facets of the industry are moving.

Over the years, hangars have developed from large sheds to architectural masterpieces, the latter being driven by state owned airlines wanting a statement building at the country’s international airport in the capital city and by the Airbus A380, simply through the building having to accommodate such a large aircraft.

That trend has now reversed, with increasing emphasis on simpler designs and concern for the environment, as can be seen by the activities of some of the industry’s major players.

Jewers Doors

Jonathan Jewers, director at Jewers Doors, says the market for commercial MRO hangars has ‘fallen off a cliff’ as a result of COVID. However, there has been strong demand from the military and for the company’s non-aviation industrial doors, used in buildings such as fire and ambulance stations and railway and metro depots.

A recent military contract was for Calidus in Abu Dhabi, which has developed the B-240 light attack aircraft, 24 of which have been ordered by the United Arab Emirates armed forces. These are being prepared in a new Flight Preparation and a Flight Assembly facility at Al Ain International Airport facility that was completed in 2020. This features two hangars, each with a set of Esavian Type 126 sliding doors measuring 30m wide by 5.6m high and fully clad with insulated flat sandwich panel cladding. The doors have six leaves that are electrically operated, with three sliding to each side of the hangar.

One bright spot has been new maintenance facilities for business aviation, which has experienced an upturn as the wealthy have looked for alternatives to commercial airlines during the pandemic.

Another 2020 project was to supply and install three sets of Esavian Type 126 doors for a 20,900m² Customer Support Service Centre for Gulfstream Aerospace Corporation at Farnborough Airport in the UK. The new facility can easily accommodate 13 large-cabin aircraft and offers maintenance, repair and overhaul services, as well as interior refurbishments and aftermarket modifications. Each of the three door consists of four door leaves, each 16.98m wide, to close off the clear opening of 67.4m wide by 9.25 m high. Each leaf, which is fitted with a continuous band of double-glazed windows at eye level, can move independently of each within the opening to allow multiple aircraft movements in and out of the hangars.

Currently, the company is supplying doors to Execujet’s prestigious new hangar at Dubai South, also a further nine sets of Esavian Type 126 doors for the Turkmenistan Presidential Code C (narrowbody) and Code F (general aviation) hangars at Ashgabat Airport.

Jewers says he has noticed some promising movement in the market recently, with tenders for new hangars in Europe and Asia but also for the refurbishment of existing facilities.

Some of the new hangar projects may benefit from a change in regulations that does away with the requirement for a foam system for fire suppression if they are less than 4,500m². Another notable design trend is a new emphasis to incorporate sustainability and reduced life-cycle operating costs, he adds, although some are calling for semi-permanent fabric structures as opposed to conventional hangar designs, although a part of this is may be to show the building as equipment on the books, rather than an asset. Other trends include rainwater harvesting, solar panels on the roof and airtight door seals and improved thermal insulation to retain heat better.

His own company is no exception. It moved into a new purpose-built facility in June this year, with 4,245m² of factory space and a 1,115m² headquarters building. The new facility is highly insulated with energy efficient heating and cooling systems in both the factory and offices. The offices have a heat recovery system which maintains fresh air around the building while minimising heat loss. There are over 200m² of photovoltaic panels on the roof capable of generating over 42kW of power and with plenty of space to expand in the future. Excess electricity can be sold back into the National Grid. Low energy sensor controlled LED lights are fitted throughout factory — there are no light switches. Also, there are 8 EV charging points for employees in anticipation of the uptake in electric and hybrid vehicles and with provision to easily increase this number in the future.

Buildair

Felipe Cano, sales director at Buildair is also very aware of the trends towards sustainability and fabric buildings.

The Spanish company specializes in inflatable hangars, formed by linking together identical inflated tubes made from fire retardant PVC-covered fabric. These are kept constantly inflated at a relatively low pressure of 20-30mb by two independent electric motors. The company has now improved the design to retain that pressure, which it calls AIRTIGHT, which means the motors are only required when the Automatic Control System detects a pressure drop. The system also performs real-time tracking of wind speed and fire detection, with alerts being sent to a computer or smartphone. To further reduce energy needs, the motors can be powered by batteries charged by solar panels if required.

The hangars use high-resistance anchorage systems instead of traditional foundation works, enabling them to be relocated if required.

A recent project, delivered in May this year, was a hangar in Hyderabad, India, for GMR Aero Technic. The building, designed for a single Airbus A320 Family or Boeing 737, measures 62m long with a 45m clear width, giving 2,800m² of useful space, without any interior columns. The 18m clear height allows the aircraft to be jacked for undercarriage removal and testing It is fitted with an inflatable door.

Cano says India is set to become a major market as the government recently reduced the tax level on MRO work. Airlines are expected to bring their aircraft back home as a result, so there could be an urgent need for extra hangar space. The Hyderabad hangar was delivered with a lead time of just 3.5 months. He points that the door is important, as FAA and EASA make it a mandatory requirement in approving maintenance facilities, and Indian MROs may want to follow that route in expanding their customer base.

Back home, the company delivered two buildings to Lleida-Alguaire International Airport in Catalunya. This is a major location for aircraft storage and disassembly. The shelters, one measuring 25m wide, the other 20m They are used to maintain small aircraft and pilot training aircraft.

The latest project, using AIRTIGHT technology and delivered in August, is a hangar for The Helicopter Company of Saudi Arabia in Jeddah. It has a length of 46m and a clear width of 20m, giving a useful area of 920 m², and 10m clear height.

Jeddah is also the location of another Buildair hangar, this time at the opposite end of the size scale. Delivered in 2019 to Saudia Aerospace Engineering Industries (SAEI), a subsidiary of Saudia Airlines, it has a length of 80m and 75m clear width, giving a 6,000 m² covered area, while the 26m interior height allows an Airbus A330 or Boeing 777-200 ER to be jacked. It is the world’s largest inflatable building.

Away from aviation, he is seeing increasing interest from the offshore wind farm industry. Being able to quickly construct a temporary facility at a nearby coastal location is a distinct advantage, whether for construction or repair and overhaul — a 25m wide shelter can be packed into a single 20ft ISO container and erected in six hours. That also has attractions for disaster relief operations.

Rubb Buildings

Ryan Clarke, sales executive at Rubb Buildings, says there was a shortage of hangar space for maintenance before the pandemic struck. As the situation gets back to normal, the demand will only increase further, which means unconventional structures will have an advantage if they can offer shorter lead times. His company uses a steel structure clad with high-strength, heavyweight coated architectural membranes from Serge Ferrari, combined with Rubb’s own Thermohall cladding for insulation. This means a narrowbody hangar can be designed and built in six-eight months.

The latest project, commissioned in September, is located in the Bro Tathan Business Park in Wales. This new development sits on the edge of the former RAF St Athan base and is designed to attract MRO organizations by having direct runway access. The hangar was ordered by the Welsh Government and is intended to be used by new arrivals while their own facility is being constructed.

With a length and width of 50m and an apex height of 18.5m, it can accommodate a single Airbus A320 Family or Boeing 737 aircraft. The structure includes 150mm Thermohall cladding and an Assa Abloy Megadoor vertical lifting fabric door with a clear width of 42m and overall clear height of 13.5m (Megadoor is Rubb’s preferred supplier for vertical doors, Jewers for sliding doors, notes Clarke). The hangar also features a 500 lux LED lighting system, electric radiant heating, and a full HVAC system.

A previous project, in 2019, was a large MRO hangar for Turkish Technic at the new Istanbul International Airport. Measuring 82.3m long by 87.5m wide and a height of 9.8m, it has 50mm Thermohall cladding, as temperatures are higher than at Bro Tathan, and a 71.9m by 19.8m Megadoor vertical door. The size of the hangar meant that 12,000m² of Thermohall cladding and 32,000m² of Precontraint 412 and Precontraint 832 fabric from Serge Ferrari were needed. The hangar is a temporary structure — when the main MRO facility is completed, it will be dismantled and moved to another airport.

Rubb Buildings is part of Rubb Industries, which helped with the installation but the project involved Rubb UK in the early sales process and securing the contract, Rubb Poland produced the Thermohall cladding, Rubb Norway provided the advanced Tekla program modeling and Rubb USA engineered and oversaw the project.

The project generated a lot of interest says Clarke, and raised Rubb’s profile in the market. One result was a contract awarded in June to build an A380 capable hangar, measuring 300ft by 300ft and 40ft high, using a 10-span hot-dip galvanized steel frame. This will be equipped with a five panel vertical lift Megadoor system with pivoting mullions. There will also be a 12ft x 12ft electrically operated roller shutter door and four 3ft x 7ft pedestrian doors fitted with panic hardware for emergency stops and vision windows.

The customer and location have not been disclosed.

Closer to home, the company last year added a third bay alongside a two bay hangar at London Gatwick for easyJet. Although the extra bay could have been simply added to the existing building, the lay of the land meant there was a 10m gap, so walkways were installed to provide easy access.

As mentioned, Rubb is part of Rubb Industries AS, which operates in a number of industry sectors. Drawing on that experience, it was able to come up with an innovative scheme for aviation — the leasing of buildings. In this case, it was a 25m x 24m hangar which was supplied to a helicopter company for six months while it carried out a project. It will then be dismantled ready for the next customer.

Clarke comments that the demand for new hangars is coming from the Middle East and Central Europe, especially for A350/777 size facilities but there is also interest, for the first time, in paint shops, helped by improved door seals. As for sustainability, he says all the PVC and steel can be recycled.

Champion Door

Pekka Hosio, CEO and founder of Champion Door in Finland, says his company’s products are completely recyclable, being constructed of fabric covers over an aluminium and steel structure with one or two insulation layers depending on customer choice and their climatic conditions.

At the moment, he is seeing greatest demand from the military market, for new and refurbished hangars ranging size from helicopters through fighters to transport aircraft, although Eastern Europe has seen an increasing number of companies purchasing their own aircraft as a way of avoiding the complications of reduced airline activity and rapidly changing schedules. As a consequence, they also need a hangar.

One business aviation project further afield was the opening in May this year of a maintenance hangar for Hong Kong-based Metrojet at Clark in the Philippines. The building is 110m wide by 63m deep, with over 7,100m² of floor space, and 21.5m high. Five vertical lift Champion doors, each independently movable, cover a clear space of 100m x 16m. The hangar can accommodate up to 10 long range business jets such as Airbus Corporate Jets and Boeing Business Jets, while a 2500m² two-storey annex building at the rear of the hangar with workshops, stores, staff and customer offices and lounges with available space for a dedicated Fixed-Base Operator (FBO). There is 11,000m² of apron space in front of the hangar with an exclusive private taxiway. The facility, with the doors, has been designed to the highest international standards including typhoon and seismic loadings.

Closer to home, the company supplied its NK4 Warm doors, the highest thermal rating, to a new two-bay narrowbody that opened in February 2020 at JOB AIR Technic MRO hangar in Ostrava, Czech Republic.

In 2019, it worked with French construction company MAS BTP on a hangar extension at Airbus in Toulouse. The extension at the front of an existing Beluga ST hangar used doors measuring 65m in width and with a maximum height of 24m, enabling the hangar to be used by the larger Beluga XL.

Talking of standards, the company has been involved for four years in helping to update the UFGS-08 34 16.20 specification of the US Naval Facilities Engineering Systems Command (NAVFAC). These are regarded as the world’s most detailed and strictest guide for fabric fold-up doors. The revised specification now includes technology that has been used for a long time by Champion Door in all its doors, in aviation, shipbuilding and industrial applications.

Hosio points out that fabric lift doors work well in hot conditions, where the tightness of the fabric keeps heat, sand and dust away from the building and from disturbing work. Unlike traditional lift door solutions, no dust or dirt can accumulate on the ends of the Champion Door’s door side rails or door joints, which could, in the worst case, stop the door from working.

They are also suited to cold conditions — the company is Finnish, after all — where traditional door solutions may have difficulties. Fabric doors do not freeze or jam, even if there is ice and snow around while heat stays inside.

A good example is from Widerøe, the Norwegian regional airline, that has hangars at Kirkenes and Vadsø. These have been equipped with three-piece NK4 Warm and NK2 doors since 2005 and 2011 respectively. Both airports are around 400km north of the Arctic Circle and winter often brings sudden large temperature drops, huge masses of snow and strong, violent winds. The most important job for the doors, which are opened several times a day, all year round, is to keep the snow and wind out but they must also keep the hangar warm for personnel and the aircraft protected from the weather. This is particularly important if there is a need for urgent maintenance or repairs, which can be carried out at Kirkenes — Vadsø is for parking only. Kirkenes also carries out deicing operations in the hangar, so those doors may be used more often.

Equipping maintenance personnel in the aerospace industry with the proper tools necessary to perform their required work safely and efficiently is critical. One of the most crucial tools that maintenance personnel need is a quality work platform that gets them very close to where they need to work. In the aerospace industry, this is often easier said than done. Thus, a reliable work platform is a key element that can sometimes be overlooked. Furthermore, the design and fabrication of work platforms involves many considerations and potential customizations that may not always be top of mind. Certainly, as the MRO industry has evolved, so have the demands on aerospace maintenance personnel as they pertain to the development and utilization of a work platform.

Work platforms are nothing new. Simple work platforms have been utilized in the industry for years. However, as technology has improved, so have the options available on work platforms. This evolution has led to the need for custom fabricators and designers to stay ahead of the demand and evolve along with the industry. There are features in today’s work platforms that simply weren’t available or even considered 20 years ago. What’s important to the industry today is much more advanced than ever before. In addition to more safety considerations, today’s aerospace maintenance worker prefers a work platform with improved mobility, configurability, worker access, utility availability and specific material selection. These elements all must be top of mind for designers and fabricators in order to deliver an efficient, effective platform.

Safety is typically the number one priority for maintenance workers. Therefore, first and foremost, a work platform must follow OSHA guidelines. Unfortunately, there are still work platforms in use today that do not meet the most current guidelines. This can be due to a variety of different reasons. For example, perhaps there are not sufficient handrails, or the incline on a certain set of stairs doesn’t satisfy the OSHA’s requirements concerning how steep they can be. There are countless elements that OSHA outlines pertaining to the safety of work platforms and designers and fabricators need to be confident that the equipment they are ultimately delivering meets these standards. Every single facet of the work platform must meet the guidelines. Not a single element can be overlooked.

Load rating is certainly one of the most important safety elements that must be considered when designing a reliable work platform. This starts with the designer having a good understanding of how the platform will be used, the number of people who might be on it at one time and any equipment that might be used on it, and then designing the work platform accordingly.

A development that has continued to gain momentum is the demand for non-slip walking surfaces. The safety implications associated with ensuring that walking surfaces have this characteristic cannot be overstated. To be clear, striving toward a non-slip walking surface is not new, but the technology has most certainly evolved over the years. Tread plate has been around for quite some time. This was one of the most common ways that this challenge was tackled. Tread plate, however, didn’t always protect against slips due to moisture or chemicals on the walking surface. There are a multitude of reasons why a work platform may get wet or oily. It could just be due to the nature of the work being done. Unfortunately, when these traditional surfaces get wet or oily, they could become extremely slippery. At that point, the non-slip aspects of the surface may as well not exist.

Today, there are options in the form of slip-resistant roll-on, spray-on and brush-on coatings. These have been known to perform better when moisture or oily substances are present. Additionally, there has been rising demand for using slip resistant engineered wood installed over corrugated metal decking. One particularly innovative solution involves the application of a metallic grit substrate directly onto a metal walking surface. It is an interesting process to apply this technology. A thermal spray containing the grit material is applied at a very high temperature to the walking surface material. When it cools, the non-slip characteristics develop. The most attractive element of this technology is its longevity. Unlike other grit materials added to surfaces that wear down and become less effective over time, this process surface holds up very well, even when exposed to moisture or oils.

Work platforms also cannot contain any components that might present hazards in the environment where they are used. For instance, if the platform will be used in an environment with explosive gases, such as in a paint booth, careful attention must be paid to the lights and other electrical devices on the platform that might create a spark and possibly an explosion.

Additionally, attention must be given to the material selected to build the platform. Depending on the environment the platform will be used in, only certain materials may be permitted. For example, chemicals may be present in a certain environment that will have a negative effect on a certain type of material. This degradation can ultimately compromise the integrity of the structure. Material selection also comes into play for platforms used in certain parts of the world, as locations near the ocean, which have high concentrations of salt in the air, or areas that are especially humid, can affect how a material performs over time.

Other elements that designers need to be aware of is the need for fall-restraint tie-off points for the various maintenance activities that will inevitably be performed that require this extra safety. Smaller but still critical features include the padding added to various points on the platform in the form of foam or rubber safeguards. These precautions are needed to protect both the items being maintained and the people maintaining them.

In addition to being safe, work platforms must be as practical and useful as the fabricators can possibly make them. This starts with mobility. In the past, even with mounted casters, work platforms were extremely difficult to move around. With improved technology, this is no longer the case. The caster industry has learned that by installing multiple wheels on a single caster, friction is greatly reduced, especially when getting a stationary caster rolling. Through these and other improvements, a single maintenance worker can more easily move by themselves what used to take multiple people to move.

In addition to easier movement, the industry today is looking for work platforms to be nimble. The platform must be designed to perform a variety of different tasks. Thus, the platform must have a robust configurability. It must be operable at different heights and accommodate any kind of unusual situation where a maintenance worker must get to a hard-to-reach area. This doesn’t just mean vertically, but horizontally as well. Slider decks and removable panels can be installed to achieve this goal.

Finally, there are many more options available in terms of utilities that can come with today’s maintenance platform, and fabricators need to be aware of the various demands that may come their way. Requirements may come in the form of hydraulic, pneumatic, compressed air or vacuum systems needing to be installed on the platforms. Are the electrical requirements going to be single, multiphase or low voltage? All could be a possibility. In the modern age of communication, data requirements must be considered. Enough data cables will need to be run to accommodate the number of computer workstations required.

Work platforms are anything but simple today and it’s important for fabricators and designers alike to keep a pulse on the growing demands from end-users in terms of safety and use.

Ken Wasiuta is the vice president of WB Industries, a custom metal fabrication company that builds and installs product solutions designed to improve safety, efficiency and performance. Many of WB Industries’ products are integral in local, national and international manufacturing facilities, military bases, aircraft carriers, public areas and within the country’s infrastructure. WB Industries applies customer specific requirements to its projects and work to several industry standards including NASA, Boeing, Lockheed Martin, AMS, AISC, IBC, ASTM and MIL specs.

The aerospace supply chain is like the weather: Everyone complains about it from time to time, but no one seems to know how to fix it. Necessary aircraft parts are often out of stock or awaiting production, while those that are available can be difficult to access due to distribution and delivery problems. The result is frustration for MROs and their clients, plus aircraft parked on the ground rather than earning money in the air. “Poor supply chain management techniques introduce risk to the overall productivity and profitability of our industry,” said Daniel Adamski, Kellstrom Aerospace’s executive vice president of Distribution. “Ultimately, a poor supply chain affects our bottom line,” added Mark Longmuir, vice president of Supply Chain and Operational Excellence at AMETEK MRO.

A poor supply chain also damages the airlines’ relationships with paying passengers, who were already unhappy with their carriers before COVID added extra chaos to the mix. “The largest impact is Aircraft On Ground (AOG) — either planned or unplanned,” said Rusty Coleman, Surgere’s vice president of Digital Transformation. “When you are sitting in an aircraft at the gate waiting because the part to fix it is unavailable, you miss the connecting flight and the meeting you had scheduled. While this is not new, lack of airworthy part supply makes this devastating as we are trying to get back to normalcy in our business and personal relationships.”

What is Wrong With the Aerospace Supply Chain?

In a perfect world, airlines, MROs, and OEMs in the aerospace supply chain would order parts on a consistent basis. Such reliable sales would financially enable manufacturers to keep producing the parts the industry needs. They would then be distributed to end users in a timely and efficient manner to all corners of the globe.

This perfect world would also offer multiple sources of aerospace parts to end users, so that production delays/shutdowns at one manufacturer would not disrupt the supply chain. As well, these manufacturers would produce parts for legacy aircraft (as well as new models) in volume, so that owners/operators could keep them all flying without experiencing supply shortages.

In the real world life isn’t like this, which is why the aerospace supply chain is plagued by shortages of necessary parts and delays in accessing those that are available. To save money in recent years, airlines, MROs and OEMs have reduced the quantity of parts they keep in their inventories, resulting in fewer sales by parts manufacturers. Many end users have also signed ‘single source’ deals with specific suppliers, making thee users vulnerable if something should impair the suppliers’ ability to provide these parts as promised. The result: A very imperfect world where parts manufacturers lack the financial means and incentives to keep the supply chain fully stocked.

“Fiscal decisions were made to maximize profits, reduce costs, or maybe ensure better business outcomes by single sourcing,” said Coleman. “Manufacturing capacity and capability were thus fiscally restrained.”

Even when end users are willing to forego single sourcing parts, “finding a second source for a component with supply chain issues is not an easy fix,” said Darren Spiegel, AAR’s vice president and general manager of OEM Aftermarket Solutions. “Due to the safety and regulatory requirements of aerospace, it take times to get a new vendor qualified, which could be time and cost prohibitive. As well, in many cases OEMs are beholden to their current vendor base and their ability to produce subcomponents in a timely manner.”

“The issue is not just supply,” he added. “Even if the supply was perfect, unpredictability of demand would persist.”

Meanwhile, the availability of ‘green-time engines’ and other used parts with some lifespan remaining on them have allowed airlines and MROs to reduce their new parts purchases. Add the lack of incentive for manufacturers to make parts for less-popular legacy aircraft, plus distribution issues in hard-to-reach parts of the globe, and one can see why the aerospace supply chain has its problems.

Nevertheless, aircraft need to be kept flying. So “purchasing professionals are using all the tools in their toolkits to secure supply,” said Coleman. “Many in the supply chain are working extraordinary hours in minute hour-by-hour details to secure the parts and the certifications needed for flight worthy components.”

Then Came COVID

The devastation wreaked by COVID-19 upon the global aerospace industry is nothing less than breathtaking. “By the end of April of 2020, 64% of the global commercial active fleet was set down due to COVID,” said Adamski. “The gradual return to service of aircraft over the last year has left scars on the aerospace supply chain.”

It wasn’t just the pandemic-induced reduction in flight hours that reduced demand for parts during 2020. “With so many aircraft grounded, airlines swapped out aircraft and green-time engines to avoid maintenance,” he said. “Purchase of parts was put on hold wherever possible by airlines and MRO shops alike to conserve cash, starving the aftermarket supply chain of sales to sustain operations. Once you power-down the commercial aerospace supply chain machine on both the OEM and aftermarket side, it takes time to re-energize the machine to restore its optimal function.”

Visualizing the end-to-end complexity of the supply chain ‘machine’ is no easy matter. This is a vast network that starts at the mines, oil wells, and chemical factories that provide raw materials such as ore, oil, and chemicals. It then progresses through the refinement of these raw materials to produce aluminum and other necessary metals, plastics, and carbon fibers – and then onto the creation of aircraft parts and systems, including semiconductors, tires, wiring harnesses, and the myriad of components needed to make an aircraft fly.

This complex, already hard-to-balance network was hammered by COVID. Thanks to pandemic-driven lockdowns and border closures, “the supply chain has seen reduced productivity at all levels and at all supplier tier levels, crippling the ability to service demand at all stages of the end-to-end supply chain,” said Alfred Baumbusch, Maine Pointe’s executive vice president and engagement partner for Aviation, Aerospace & Defense Practice. “In addition, labor was isolated and limited to home base locations to minimize the spread of the virus. This reduced, or in some cases completely stopped, production and delivery of materials.”

With production being slowed or stopped, the links of the aerospace supply chain came under strain as everyone faced cash flow crunches. “The resulting financial pressures caused executives to quickly re-think their strategic plans, and shift to survival mode, thereby further reducing their ability to service clients,” Baumbusch noted. “This in turn applied significant pressure to some suppliers’ financial positions creating serious solvency issues, which necessitated financial aid by Tier 1 or OEM suppliers. All these factors resulted in increased M&A (merger and acquisition) activity throughout the industry, which continues to play out.”

“COVID has affected both labor and material availability as well as the predictability of demand,” said AAR’s Spiegel. “In good times, any one of these posed supply chain issues. Together, they are unprecedented.”

No Easy Recovery

If 2020 was the year in which COVID-19 crippled the aerospace business, 2021 appears to be the year where business begins to recover. But the fact that airliners are returning to service and manufacturers are seeing orders increase doesn’t mean that aerospace supply chain issues will suddenly ease. As Kellstrom Aerospace’s Adamski noted, a supply chain isn’t a machine that can just be switched on or off.

This brings us to the first big challenge of the COVID-19 recovery: Getting the aerospace supply chain back up to pre-COVID delivery levels, or hopefully better.

Let’s start with OEMs. After the pandemic hit in 2020, airlines delayed or dropped their new aircraft orders. As a result, “Tier One and Two OEM suppliers were in many cases left with stranded inventory and the need to suspend production and reduce headcount to preserve precious liquidity and ride-out the storm unless they could quickly diversify into less-impacted market segments,” said Adamski. “In some cases, long lead time raw material orders were cancelled including castings and forgings, thereby causing a cold-start scenario to resume production for many critical parts and materials with much longer than normal lead times.”

“Aftermarket suppliers also face challenges,” he added. “With a significant portion of the aircraft grounded for much of the last year, speculation had been swirling in the industry about a wave of aircraft retirements leading to a tsunami of surplus material. But the reality has painted a different picture so far.”

The reason: According to Adamski, only 665 aircraft were retired in 2020 compared to 674 in 2019 and 195 as of mid-June 2021. This means the anticipated ‘tsunami’ of recoverable used parts seems unlikely to materialize anytime soon. “While certain USM material may be available, LLP stacks, HPT blades and other A parts with acceptable traceability and remaining hours and cycles may be less plentiful than one may assume,” he said.

Skilled employees are also needed to bring the aerospace supply chain back to pre-COVID levels. Unfortunately, the labor shortage that was dogging the industry before the pandemic “has been magnified for companies trying to ramp up after COVID-related cutbacks, said Spiegel. “This issue is even greater for sub tier parts OEMs that might have shifted labor to another industry with more predictable demand.” To make matters worse, “aerospace, in most cases, is not high volume and requires additional specialized talent and processes that cannot be restarted without a significant training effort,” he observed.

The result? Lead times for OEM materials published prior to the COVID-19 downturn no longer apply in many cases, said Adamski. “Similar challenges exist in the aftermarket, with OEM lead times having impacted by supply chain disruptions.”

His concerns are echoed by Mark Longmuir. “The primary issue that AMETEK MRO is experiencing is lengthened lead times, and we are adjusting our planning data accordingly whenever we see them to protect supply,” he said. “We are also constantly monitoring our materials’ quotes for inflation, which has started to creep into our supply.”

Fixing Post-COVID Supply Chains

As the pandemic’s depressing effect on global aviation continues to wane, the aerospace supply chain is entering into Recovery mode — and encountering the challenges that accompany this kind of ramp-up effort. These issues include delays in the availability of raw materials and finished parts, increased shipping costs, and delivery issues in the trucking industry, which is having its own supply chain and labor issues thanks to COVID.

Fortunately, there are ways to fix the post-COVID aerospace supply chain, or at least make it function more smoothly than it does today.

“Attending to four key areas will bring an immediate impact and improve the supply chain,” said Maine Pointe’s Baumbusch. “First and most obvious is to take a fresh look at the business: Suppliers at all stages of the supply chain need to prepare a roadmap by bringing together procurement, logistics, operations, and leadership to establish a clear and effective path forward.”

“Secondly, it is essential to consider utilizing more accurate and useful data analytics, which would allow for better and more proactive decision making,” he continued. “Third, better visibility of the operations between suppliers and customers will improve the accuracy of early warning indicators. Lastly, the economic recovery of other key industries such as automotive, transportation such as air travel, and material/supply delivery, will support increasing inventory levels to Tier Ones and OEMs, and ultimately, to the buyers.”

One further way to fix the post-COVID supply chain may well be the most difficult, namely by monitoring and analysing air traffic increases to forecast what kind of supplies will be needed to support the revived airline industry in the months to come.

“The trick now is to accurately forecast a COVID recovery so OEM production can prepare now,” said Spiegel. This is a service that AAR is providing to its OEM clients, using future-looking data to help them predict/plan engine shop visits, fleet forecasts, flight hour projections, and general fleet market intelligence. “For parts that might have a 150–300-day lead time, an inaccurate forecast now is not easily rectified in time to meet future demand,” he admitted. “This inaccuracy can inhibit fleet readiness and limit the recovery potential for the end users. Still, looking forward can help limit the reliance on forecasts based on noisy, COVID impacted, rearward-looking data.”

Surgere’s Coleman offers a one-word suggestion to improve the post-COVID supply chain: “Technology! The technology exists to support workers to improve their capability and their capacity,” he told AVM. “Items like IoT (Internet of Things, aka web-connected devices and machines), Analytics, Machine Learning, Artificial Intelligence and Blockchain can be the means to a digital end. Use these digital tools to enhance the capabilities of the workforce you have. Use these technologies to simplify workloads, and use the system-to-system connectivity to make the user experience inviting and efficient.”

Progress to Date

Some aerospace companies are making progress in fixing the industry’s supply chain, or at the very least, making it better than it was before.

A case in point: “AAR has had multiple OEMs come to us to help prepare for a COVID recovery by forecasting and stocking material,” said Spiegel. “With our forecasting ability we are able to provide a service that is taking some of the guess work out of what material should be produced.” The company tempers these forecasts using market intelligence gathered by AAR’s global sales force. Once an AAR forecast has been accepted by an OEM, AAR provides future order book coverage to allow the OEM to plan for known demand based on AAR’s forecast and parts purchases.

AMETEK MRO is using the Lean management techniques typically found in manufacturing and production to manage its supply chain efforts. This is not an easy task: “I’ve found that the requirements of the MRO industry on supply chain are much more demanding and complex than those of an OEM-only manufacturing environment,” Longmuir said. “Supporting tens of thousands of products on our capability list, combined with limited ability to predict what products will arrive on our dock on any given day, requires an agile support team and processes that guarantees the right repair and overhaul material is available immediately.”

“Kellstrom Aerospace offers multiple aftermarket platforms with solutions for various challenges posed by COVID-19-induced supply chain dysfunction,” said Adamski. For example, the company’s OEM distribution business “provides needed balance sheet relief for OEM manufacturers while managing, forecasting, and provisioning the correct mix of OEM material available from stock with 24/7/365 AOG support and global stocking locations.”

Kellstrom Aerospace is backed by its large private equity parent company AE Industrial Partners. This gives Kellstrom Aerospace the deep pockets necessary to make large inventory commitments with suppliers. As well, “we use our proprietary inventory forecasting tool in conjunction with our ERP system to forecast material demand effectively to maintain an average distribution fill rate of 98%-plus on our 30-plus OEM distribution lines in service,” said Adamski. (An additional strength: Kellstrom Aerospace’s Used Surplus Material (USM) business tears-down entire aircraft and engines to offer high quality/ best value used parts to customers.)

Hoping for a Better Supply Chain

The concerns that these aerospace companies have about the post-COVID supply chain, and the actions they are taking to try and make the supply chain better, underscore just how important the smooth flow of parts are to the overall health of commercial aviation around the globe.

“If supply were not an issue, aircraft, engine, and component repair Turn-Around-Times (TATs) would be quicker, market pricing would be more predictable, and overall A&D forecasting would be more accurate,” said Adamski.

“If supply were not an issue, forecast demands throughout the supply chain would be more stable, financial profitability would recover, and unemployment reduced, increasing the health of the overall economy,” Baumbusch added. “The end-to-end supply chain would return to a more harmonious state, and the natural state of supply and demand would work. An increase in future developments would naturally drive the industry forward, resulting in improved R&D and other investments, thereby increasing overall operational performance.”

To say none of these companies wanted the supply chain challenge would be an understatement. But it is one that they are all committed to addressing as best they can.

“I view the supply chain situation as a challenge that none of us asked for, that tests our ability to be agile and still meet customer expectations,” said Longmuir. “Nevertheless, we will continue to ‘turn the knobs’ that allow us to meet customer requirements.”

Back in June 2021, Aviation Maintenance magazine heard from widebody engine MROs with respect to the challenges they’re currently facing in serving airline clients, the support programs they provide to help these clients manage their engine maintenance costs, and the advice these MROs had to offer clients for getting more value from their services (‘Widebody Engine MROs Talk About Challenges, Support Programs and Advice to Customers’).

It is now time for narrowbody engine MROs to share their views on the same topics. Here’s what they had to tell us.

AFI-KLM E&M

In addition to accommodating widebody engine clients, AFI-KLM E&M’s MRO facilities in Amsterdam-Schiphol, Paris-Charles de Gaulle and Paris-Orly offer narrowbody engine maintenance and overhaul services on the CFM International (GE Aviation-Safran) CFM56 engine used on Airbus A/318/A319/A320/A321 and Boeing 737 Next Generation airliners. AFI-KLM E&M provides the same level of support to the CFM International LEAP engine, which is being used on the Airbus A320neo, Boeing 737 MAX and Comac C919.

Their biggest challenge? Keeping these engines serviced during pandemic shutdowns and parts shipping delays has been difficult, but AFI-KLM E&M has been able to cope. “In the current COVID situation it is essential to manage the supply chain in order to lower maintenance costs, and to be creative and innovative to get through this period,” said Michael Grootenboer, AFI-KLM E&M senior vice president Engine of Group Engine Products. “Industry-wide, it will be a further challenge to manage the supply chain and the pressure on overhaul capacity once traffic starts picking up again.”

To help its airline narrowbody engine clients keep their costs under control — especially now when cash is tight due to COVID — AFI-KLM E&M offers a range of service contracts based on different pricing models. These pricing models include Cost per Flight Hours, Firm Fixed Price (FFP), Not to Exceed (NTE), and Time & Materials (T&M). “The model provided depends on each customer’s operations,” Grootenboer said. “We adapt our answer to be the best fit for each customer.”

When it comes to offering value-maximizing advice to narrowbody engine customers, Michael Grootenboer’s answer is short and sweet: Book your shop visits now to ensure that you can be served in a timely manner. “Airlines have avoided engine overhauls to preserve cash because of the Coronavirus crisis,” he explained. “MRO capacity will be scarce when the market picks up again and increased traffic will be back to 2019 levels for narrowbodies first. So securing engine MRO slots now to keep your operations going is essential.”

Lockheed Martin Commercial Engine Solutions

Lockheed Martin Commercial Engine Solutions (LMCES) provides full overhaul capability for Airbus and Boeing narrowbody engine platforms such as the CFM56-5A/-5B (A320 engines), CFM56-7B (B737 engines), and CFM56-3 (older generation B737 engines). LMCES also maintains non-narrowbody engines including CF34-3 (regional jet engines), and CF6-50 (widebody military refueling tanker engines). All MRO work is performed at the LMCES engine shop in Montreal, Canada.

From LMCES’ vantage point, there is one primary business challenge dogging the airline and MRO industries — COVID-19.

“Globally, narrowbody operators continue to be adversely impacted by the pandemic,” said David Bridges, LMCES’ director of Strategy & Business Development. Their cash flow woes are trickling down to the MRO industry. “Although many U.S.-based operators have experienced a recovery in their passenger service, most remain engaged in aggressive efforts to avoid or delay expensive engine overhauls whenever possible,” he said. “Some of those efforts involve the renegotiation of aircraft lease return conditions and utilizing remaining life from ‘green-time’ engines to avoid short-term engine maintenance costs. In general, most of the airlines operating narrowbody aircraft are seeking flexible, customized work scope solutions for any engines that require in-shop maintenance,”

The numbers tell a stark tale: According to LMCES, commercial demand for engine MRO services across the industry was roughly cut in half in 2020 because of COVID. To stay afloat financially, this MRO shifted its short-term focus to narrowbody aircraft lessors and military opportunities.

The results of this focus shift have apparently paid off. In late 2020, LMCES signed a long-term narrowbody engine service agreement with leasing company Fortress Transportation and Infrastructure Investors LLC (FTAI) for CFM56-5B/-7B engines. LMCES also signed a long-term MRO contract with the United States Air Force for its F108 engine, which is the military version of the CFM56-2.

“LMCES continues to anticipate strong demand from its military sustainment customers through contracts with the U.S. government for KC-10 and F-108 engines going forward,” said Bridges. “With more than $1 billion in new contracts, our team is proud to be growing with many career opportunities to join the team in Montreal.”

Back to the airline MRO business: When it comes to narrowbody engine service plans, “commercial customers mostly desire, and LMCES mostly offers, Firm Fixed Price (FFP) contract options,” Bridges said. “FFPs allow LMCES to work closely with its customers to optimize costs.”

“Conversely, Time & Material (T&M) programs shift risk to customers while Flight Hour Agreements (FHAs) shift risk to the MRO,” he observed. “Neither T&Ms nor FHAs allow as many opportunities as possible for collaboration on engine cost reduction.”

When it comes to getting more value for their engine MRO dollars, David Bridges’ advice to narrowbody engine owners is to take advantage of a new joint venture between LMCES and FTAI called ‘The Module Factory’. It is a dedicated commercial engine maintenance center operated by LMCES that focuses on the modular repair and refurbishment of CFM56-7B and CFM56-5B engines. “The Module Factory offers a unique product from typical engine MRO work by utilizing plug-and-play modules and standardized work scopes,” he explained. “It is designed to significantly lower turn-around-times (TATs) and to lower cost per cycle for narrowbody engine customers.”

MTU

MTU Maintenance is predominantly focussed on the narrowbody engine MRO market. They offer full overhaul services for:

• CFM56-7B engines at MTU Maintenance Hannover and MTU Maintenance Berlin-Brandenburg, CFM56-5B/7B engines MTU Maintenance Zhuhai, and the CFM56-2 variant at MTU Maintenance Canada;

• International Aero Engines (IAE) V2500 engines (Airbus A320 family, McDonnell-Douglas MD-90, and Embraer KC-390) at MTU Maintenance Canada, MTU Maintenance Hannover and MTU Maintenance Zhuhai;

• Pratt & Whitney PW1100G-JM engines (Airbus A320neo) at MTU Maintenance Hannover and EME Aero, with services being added at MTU Maintenance Zhuhai (while some PW1100G-JM piece part repairs are also carried out at MTU Maintenance Berlin and MTU Aero Engines in Munich);

• LEAP-1B and soon LEAP-1A engines at MTU Maintenance Zhuhai;

• Pratt & Whitney PW2000 engines (various aircraft including Boeing 757s) at MTU’s Hannover facility.

As with other narrowbody engine MROs interviewed for this story, coping with COVID remains a major challenge for MTU — in this case, dealing with growing and unpredictable demand as airline travel returns to normal worldwide.

“Some positive signs have already been observed in Asia (where 85% of China’s fleet is now active), North America (over 70% active) and Europe as regional and domestic travel has started to recover,” said Fabian Schoen, MTU Maintenance’s director of Programs. “This renewed traffic has predominantly been with narrowbody engine aircraft. We are prepared for this and expect to see our MRO levels recover in 2022/23. Furthermore, we retained our highly-qualified staff during the pandemic and are ready to support our clients as the recovery occurs.”

As for service programs? Given the wide range of narrowbody engines supported by MTU, it makes sense that the company does so in a variety of ways.

“For operators of newer engines, our focus is on generating more flight hours with customized solutions,” said Schoen. “We achieve this by intelligent fleet management that optimizes removals across a defined period. Such services are complemented by predictive maintenance, based on engine trend monitoring, on-site services and spare engine support.”

When it is time for a newer engine to make an MTU shop visit, this MRO reduces the engine’s servicing costs through a combination of customized work scoping, advanced EASA-FAA approved repairs and engineering expertise to help lower overall costs. “We call this program PERFORMPlus,” Schoen said. “It is particularly relevant for customers preparing for increased flight schedules later in the year.”

MTU’s SAVEPlus program for mature narrowbody engines — which typically require more work in the shop — is meant to keep their costs down as well. To make this happen, “our solutions include smart repairs and tailored work scopes to suit operators’ remaining flight periods, as well as material salvation and intelligent teardowns,” Schoen said. These services can be combined with MRO alternatives such as leasing green-time engines to clients through MTU Maintenance Lease Services or exchanging less-mature engines in alignment with the aircraft’s remaining lifespan. “Furthermore, we offer all service contract types including Fly-by-Hour and Time & Material,” said Schoen.

When it comes to client advice, MTU doesn’t offer any one-size-fits-all wisdom for narrowbody engine owners/operators. But the company does recommend that clients talk to their MROs about their needs as soon as possible, to ensure that they can be met in a timely manner as global airline traffic ramps back up.

“Currently, fleet planning is highly dynamic, so we are working with our customers on finding the best solutions for their fleets, to enable our customers to get the most engine life and value from their assets,” Schoen told Aviation Maintenance magazine. “In doing this, we expect to see a continued trend away from traditional planning with fixed maintenance intervals to more individually-tailored solutions. Some airlines are concentrating on short-term savings with cash preservation as the main objective, while others are focusing on long-term planning. MRO providers must flexibly meet both these goals to provide the best solution for customers in today’s market.”

Pratt & Whitney

Pratt & Whitney has MRO service centers around the globe. There are nine International Aero Engines (IAE) party company facilities, Pratt & Whitney being a key partner in the IAE consortium. Three of those IAE MROs are managed directly by the famed engine manufacturer and its joint ventures. There are also nine active GTF MRO shops in Pratt & Whitney’s GTF MRO network.

Not surprisingly, Pratt & Whitney services a whole range of airliner engines. They include the PW1900G (Embraer E-Jets E190-E2/E195-E2), PW1500G (Airbus A220), PW1100G-JM, V2500 A320ceo family, PW2000, and the CFM56.

Beyond the inherent technical intricacies involved with maintaining and overhauling jet engines, COVID-19 has been the biggest business challenge facing the company in recent months. “We saw several trends during the pandemic,” said Joe Sylvestro, Pratt & Whitney’s vice president of Aftermarket Global Operations. “Among these: Aircraft powered by Pratt & Whitney GTF engines were often the last to stop flying and the first to return to service due to the engine’s fuel efficiency. Cargo aircraft were less impacted by the pandemic than passenger aircraft: In fact, last October the first A321 passenger to freighter conversion aircraft powered by V2500 engines was delivered to Qantas Freight. And, in general, narrowbody aircraft operators were able to benefit from green-time engine management.”

According to Sylvestro, Pratt & Whitney’s close relationships with customers gave his company “good visibility” around forecasting and scheduling maintenance, which allowed Pratt & Whitney to tailor its maintenance strategies to address the realities of the pandemic. “For example, with many aircraft inactive during the pandemic, we had a window of opportunity to incorporate planned upgrades into the GTF fleet,” he said. “Rather than slow down MRO activity, we accelerated upgrades and restored the fleet to full readiness in anticipation of the recovery. We’re currently at a world-class 99.97% dispatch reliability rate on the Airbus 320neo fleet.”

Pratt & Whitney addresses its clients’ need for service programs/contracts through its suite of EngineWise solutions. Sylvestro said his MRO offers a wide variety of customizable work scopes and payment options for both cargo and passenger air carriers. “Our comprehensive maintenance plans provide a turnkey solution where we will cover most aspects involved in engine maintenance, from health monitoring, to tailored overhaul planning, to execution of the overhauls on a dollar per flight hour basis,” he explained. “On the other end of the spectrum, we also offer transactional plans that allow the customer to bring in their engines when they choose and provide them full control over the work scope. We work closely with our customers to provide the solution that works best for them.”

Joe Sylvestro’s advice to narrowbody engine owners/operators is to keep in touch with Pratt & Whitney on an ongoing basis, so that their MRO needs can be managed efficiently and effectively. “Staying in communication is key,” he said. “If an operator can help us understand their needs, we can in turn respond more holistically to reach the best outcome.”

StandardAero

StandardAero provides MRO services for the CFM International CFM56-7B at the company’s Plant 6 facility in Winnipeg, Canada, which includes two test cells. The company is a GE Designated Fulfillment Center for the CFM56-7B and an independent TRUEngine authorized MRO provider for this engine type as well.

“We launched our CFM56-7B program in June 2009, after being selected to support WestJet’s fleet of engines under an exclusive 13-year OnPoint solution contracted by the airline with GE Aviation,” said David Green, StandardAero’s vice president/general manager CFM56/CF34. “GE subsequently agreed to extend the offload program to include engines from other airlines supported under long-term agreements with the OEM.” StandardAero also supports the CFM56-7B engines powering the U.S. Navy’s P-8A Poseidon maritime patrol aircraft fleet including engine health monitoring (EHM) support for both the CFM56-7B and the -5B variant.

When it comes to the narrowbody engine MRO business, “our biggest challenge right now is actually staffing back up to meeting resurgent demand from airlines,” Green said. “We are fortunate that the North American market, the most important for us in terms of our customer base, has rebounded strongly after the downturn of 2020, and this is driving a significant uptick in shop visits. This is allowing us to rehire many of those employees we were forced to lay off a year ago, though we now find ourselves competing with other aerospace companies for skilled technicians, as the whole industry enters a hiring phase.”

Onto StandardAero’s narrowbody engine service programs. As a GE Designated Fulfillment Center and TRUEngine authorized MRO provider for the CFM56-7B, this MRO offers a full range of OEM-authorized services for this engine. Meanwhile, to address the varying needs of its clients. StandardAero offers service contract options such as flat-rate agreements (FRA), FFP, NTE, Power-by-Hour (PBH), Power-by-Cycle (PBC), and T&M.

“Our contracts can include a range of services, including scheduled MRO, unscheduled engine removals (UERs), engineering, EHM and field service support,” said Bridges. “In terms of financing, while StandardAero does not offer in-house financing we do have agreements and relationships with various financiers, including Export Development Canada (EDC).”

Like the other MROs in this article, David Bridges advise narrowbody engine owner/operators not to delay on booking shop visits any longer. “Demand for shop visits is already rebounding strongly, driven in part by events that were deferred for cost reasons during the worst of the COVID-19 related travel slump,” he said. “As a result, operators may be surprised to find that shops are not able to offer immediate induction dates.”

While airlines continue the process of digitization, industry observers indicate maintenance is lagging the effort that could save millions of dollars while increasing productivity and increasing safety. This is surprising given the fact how fast manufacturers have integrated digital data from everything on board from inflight entertainment systems to engines which stream tons of data every minute.

“When you consider that 20 years ago means 2001, we can confidently reflect on some of the innovations and leaps forward we have made within the aviation industry,” flydocs CEO Andre Fischer told Aviation Maintenance. “However, when looking more specifically at technical records, progress has been slower. Huge leaps have been made by the aviation sector in implementing high-tech technology to improve passenger experience and make the journey much more feasible. It comes as quite a surprise that the technical and MRO side of the aviation sector still has so many paper-based processes, especially when it comes to managing technical records. Shifting to paperless is slow but we are starting to see a real mindset change for digitally driven solutions, with the pandemic giving this area a bit of a boost. As the world locked down, the ability to access records with fewer challenges started to become a priority for many operators, lessors and MROs.”

The other factor at play is fleet growth. “Digitization of records keeping is one the major changes in the technical records area,” Saravanan Rajarajan, director — aviation consulting, Ramco Systems told Aviation Maintenance. “This can be attributed to two main factors one is growth of the aircraft fleets over the last 20 years which makes the manual processing of records inefficient and the second is evolving technologies in the MRO space to digitize the data entry like electronic tech logs, mobile-based maintenance execution and the availability of technical manuals in digital format. Recent developments on remote collaborations and virtual inspections have stretched the boundaries of the technical records to manage new forms of the data like voice and videos with ability to archive and audit for regulatory purposes.”

Fischer explained since the industry entered recovery mode, it is taking time for airlines to realize the true potential and accelerate this push towards digital solutions.

“There is huge optimism though as some airlines are seeing this crisis as an opportunity to drive their digital transformation forward, which not only creates a competitive advantage but plays a role in minimizing the risks of another global game-changer like the global pandemic,” Fischer said. “While the industry is seeing the value of digitization, the lag is experienced more on the engineering side where adoption of change is a bit slower. The balance between trying to achieve 100% operational safety on the engineering side and new developments in technology is very tricky so needs to be managed very carefully to bring out the best of both sides.”

Fischer noted the lack of standardization is playing a role in slow adoption. “Regulators could play a huge role in developing standardized frameworks and committing to supporting digital initiatives to ensure that every segment of the aviation industry reaps the rewards of digitization,” he said.

Record Keeping Maintains Asset Value

Nothing brings the value of an aircraft down faster than lousy record keeping as anyone who has every maintained or tried to sell an aircraft knows. In aviation, forcing an aircraft inspector to root through mildewed boxes to reconstruct the maintenance history quickly brings the value down to zero or the cost of reconstructing those records into the hundreds of thousands.

“MROs can also benefit from more efficient ways to review maintenance records,” said Fischer. “The convenience and improved efficiency of being able to access maintenance records instantly in one centralized location from anywhere in the world already has a positive impact. Moving away from having stacks of documents being stored off-site brings a high risk of loss and damage. That risk is completely eliminated with digital records. From a business continuity perspective, COVID-19 proved that digital access of records is invaluable and drives cost savings. “

For airlines, record keeping is the difference between airworthiness and grounding of an aircraft or a fleet. Just recently, DGAC grounded Air Antilles fleet for aircraft maintenance irregularities stranding its passengers scattered among the French islands in the Caribbean. Indeed, for airlines, the issue is not only about record keeping but the efficiency of doing so as part of efforts to ensure compliance and safety and cut costs.

“It’s not uncommon to see a value of aircraft drop by 20% due to the missing records during business transactions,” Rajarajan told Aviation Maintenance. “Records management also provides the insights needed for the organizations to optimize the maintenance intervals based on their operating environments. With the majority of the items fitted on aircraft on condition and subject to rotate between the aircraft, records management becomes vital to track the configurations control, component status, hours and cycles.

“The technical records department spends considerable effort and time whenever they deal with paper-based documentation to manage error correction, reviewing the accuracy, scanning and archiving,” Rajarajan continued. “Efforts tend to be significantly higher if the organization doesn’t have a proper technical records system in place. We have seen pursuing a comprehensive technical records digitization process organization can save 40% of the department expenses owing to automation of manual process at the organizational level. The rapid progress and maturity of mobile technologies and digital content availability of technical documentation including manuals and job cards, has made the shop floor digitization a reality.”

John Stone, Ultramain vice president of Product Management agrees. “Airlines are required to maintain detailed records of aircraft usage, and aircraft maintenance including any changes made to aircraft, configurations and components,” he told Aviation Maintenance. “MROs are required to provide records of maintenance accomplished. If airlines do not comply or do a poor job of record management, they can face fines and forced closure. Aircraft resale value and lease returns are impacted by having or not having good maintenance records. Equally important, good data collection related to maintenance accomplishments allows better accomplishment of future maintenance through better planning, scheduling and contingency planning.”

Even when an aircraft is parted out, record keeping is a major part of the equation as evidenced by the fact record keeping, inspecting and refurbishing are part of realizing the value of parts that can be re-used. For instance, Tarmac Aerosave and VAS Aero Services are breaking down former Singapore Airlines Airbus A380s for owner Dr. Phillips Group as they recycle 90% of the giant jumbo. Paperwork — written and photographic documentation — for the 5,000 parts harvested from the aircraft can take a month or more of the three or more months aircraft recycling takes. But the effort could yield between $30 million and $50 million for the owners.

Industry Slow to Go Paperless

Today, with modern aircraft streaming tons of data, it has become more important than ever to integrate Artificial Intelligence (AI) and Machine Learning (ML) into the process and aviation maintenance vendors such as RAMCO, flydocs and Ultramain are bringing the technology to bear. They are all part of the digital transformation taking place in the maintenance bay supporting paperless operations.

flydocs reported digital document management systems are playing a huge role in streamlining maintenance activities. “What these digital systems often have in common is in the increased visibility of an aircraft’s entire maintenance records, easy online access and more importantly, reporting functionality that contains all the required insights,” Fischer advised. “It also enhances fleet airworthiness, allowing customers to focus time and resources on the core business.”

He discussed how flydocs’ records management platform is transforming how the commercial aviation sector undertakes end-to-end aircraft records management whilst delivering substantial efficiencies and cost savings for its 75 clients worldwide.

“The flydocs team help clients improve processes, driving time and cost efficiencies through digital aircraft records management,” he said. “They are empowered by the flydocs platform, a centralized online system, which provides internal and authorized third parties with instant access to millions of approved aircraft records for compliance verification. The system transforms complex, unstructured data into industry-standard formats; and through integration with existing ERP/M&E systems, it automates and streamlines record builds to provide the right information exactly when they need it, resulting in compliance on demand, simplified end-of-lease transfers and real-time asset management.”

Sea Change Unfolding

Airlines are already incentivized to adopt digital solutions to unlock the value through the end-to-end digitization process because, as Stone pointed out, the improved productivity, reduced operational costs and reduced overhead compared to traditional paper-based record keeping system which is more costly. Ultramain has two product divisions, M&E/MRO and Onboard Systems each designed for full paperless operations using the ULTRAMAIN ELB software to address a broad spectrum of aviation maintenance needs. including maintenance (line, base, engine, shop) with materials, labor, documentation, ELB and procurement. Complementing this is several mobile applications including Mobile Mechanic, Mobile Inventory and Mobile Executive, which help streamline workflow, reduce costs and improve operational efficiencies. The system provides real-time maintenance work status and completion.

“This real-time visibility into work being performed, coupled with digital sign-off is important because it helps operators by reducing the delays associated with paper-based systems,” said Stone. “Meanwhile, our ULTRAMAIN Labor Management ensures engineers are current, certified, and qualified to perform the tasks assigned to them. It does not let them log onto a task unless they are. In fact, ULTRAMAIN will not let you even assign a task to someone who is not qualified to perform it and it will not let engineers sign off tasks unless they have proper authority, improving safety and accountability. In addition, NRI approvals and billing agreement is enforced before allowing work to begin on them.”

flydocs also sees digital maintenance record keeping as supporting airline growth in addition to improved compliance on demand, improved agility to adapt to operational business process changes, increased workforce productivity, job satisfaction and a reduction in aircraft delays.

Benefits include automation of manual and repetitive tasks and integration with the entire aviation eco-system easing the workload for operators, lessors and MROs. “Routine and repetitive back-end activities are being automated to detect the exception patterns and provide intelligent real-time alerts and notifications,” Stone explained. “As the data are entered in the digital format missing sign off blocks, missing mandatory measurement readings are instantly identified for rectification. With the interdependence in the industry between the lessors, operators, MRO’s to work seamlessly with one another’s digital records enables interoperability thereby reducing the transactional costs during the asset transfers.”

Stone indicated the real-time notifications identifies when delays are happening during maintenance checks so they can be addressed quickly and to ensure customers get their aircraft, engines or components back on time, with correct electronic paperwork and with proper billing which speeds up payment.

“All this means check planning, quoting, execution, records are better and expenses lower,” he said. “Profitability is then managed and more predictable.”

AI & ML Brought to Bear

“RAMCO’s artificial intelligence and machine learning (AI/ML) capabilities leverages data and advanced algorithms to derive insights for tactical intelligence,” said Rajarajan. “By leveraging the historical records pertaining to the non-routine or defect, mechanics, while reporting a new case, are presented with the suggestions using similar cases with possible resolution options and any parts or tools required for fixing the defect. Final determination of accepting the recommendations still lies with the mechanics, even though this is tactical insight it has the potential to significantly reduce turn-around time especially during unplanned grounding of the aircraft.”

Ramco has the comprehensive technical records functions tightly integrated with maintenance execution modules, providing a single interface, technical records hub, which caters to the technical records teams. That hub then provides the complete visibility of the aircraft configuration control, component configuration and status of the fitted items and items due for maintenance from stores.

The advent of both voice and video gives aviation maintenance technicians a new tool to record data that automatically integrates records as part of the technical documentation, tagged, indexed and archived for future search, retrieval and audit purposes.

Leveraging RAMCO’s expertise of its MRO Lab in Singapore, RAMCO is actively working with customer’s specific use cases leveraging Robotic Process Automation (RPA) Bots for missing paperwork, missing data entry and accuracy reviews.

As M&E/MRO catches up to the passenger side of digitization, airlines, which continue to search for cost cutting technologies, are creating a whole new world for asset management.

This summer marked the 25th anniversary of the most complex and vexing aircraft accident in aviation history – TWA Flight 800. The vintage Boeing 747-100 had just departed from New York on its way to Paris when it suddenly exploded off the coast of Long Island. All 230 people on board were killed. As a rookie NTSB field investigator at the time, I was not involved in the years-long effort to solve the accident, but I sure do remember its impact, especially later when I taught at the NTSB Training Center where the TWA 800 reconstruction was housed (see top image at right).

The NTSB concluded that the center wing fuel tank of the 747 exploded, likely due to wire chaffing and arcing outside of the tank, which led to a short circuit that allowed excessive voltage to enter the tank through the wiring for the fuel quantity indication system (FQIS). Additionally, NTSB examinations of wiring on 26 other airplanes of varying ages (ranging from new to 28 years old) revealed that all of the older airplanes exhibited numerous examples of mechanically damaged, chafed, cracked, and contaminated wires (see image at lower right). Sharp-edged metal drill shavings (which can damage wire insulation), fluid stains, and other potentially hazardous material were also found in or near the wiring of old and new airplanes.

While not considered a “maintenance related” accident, the TWA 800 tragedy focused the MRO industry’s attention on the pitfalls of aging and improperly installed electrical wiring. Unfortunately, several more similar accidents and incidents followed in the late 1990s.

SWISSAIR Flight 111

Two years after the TWA disaster, another wide-body jet was felled by wiring problems. This time, it was a McDonnell Douglas MD-11, operating as Swissair Flight 111 on a flight from New York to Geneva, Switzerland, with 215 passengers and 14 crew on board. And, this time, I was involved in the investigation.

The date was September 2, 1998. Swissair Flight 111 was cruising at 33,000 feet about an hour after departure from JFK Airport when the flight crew reported a smell of smoke. As the smoke became dense and entered the cockpit, the crew attempted an emergency landing at Halifax International Airport in Nova Scotia, Canada. But it was too late. The MD-11 impacted the Atlantic Ocean a few miles off the coast near Halifax. There were no survivors.

Freshly promoted to the NTSB “go-team” as a systems engineer, I launched to Halifax to assist the Transportation Safety Board (TSB) of Canada since the aircraft was designed and built in the United States. I spent several weeks on a floating barge (see top right) with other investigators, sifting through piles of shredded wreckage brought up from the ocean bottom by a massive crane and bucket.

The Canadian TSB’s meticulous investigation rivaled that of the NTSB’s effort with TWA 800, including a 3-dimensional reconstruction of the front of the airplane (see lower right). Evidence revealed that a fire raged above the ceiling in the front area of the aircraft. The Swissair MD-11 was modified with an in-flight entertainment network (IFEN) for first class passengers, and it was connected to aircraft power in a manner that was not compatible with adequate emergency electrical load-shedding.

The IFEN was an approved, but inadequately reviewed, Supplemental Type Certificate (STC) installation.

A review of IFEN system installation records revealed discrepancies in the drawings and supporting documentation. No details for wire routing were provided. Additional inspections of wiring around the cockpit overhead circuit breaker panel in other MD-11s revealed loose wire connections, inconsistent wire routings, broken bonding wires, small wire bend radii, and cracked and chaffed wire insulation.

The investigation led to numerous recommendations regarding insulation flammability, crew checklist procedures, and system design. More importantly for the readers of this magazine, the accident highlighted the importance of guidance contained in FAA Advisory Circular (AC) 43.13-1B, “Acceptable Methods, Techniques, and Practices—Aircraft Inspection and Repair,” and AC 65-15A, “Airframe and Powerplant Mechanics Airframe Handbook.” These “best practices” rely heavily on the training and experience of the maintenance professionals who perform the installation work to determine proper wire routing.

More Incidents of Arcing and Sparking

Because of the TWA 800 and Swissair 111 tragedies, the aviation industry was “on edge” to say the least. Every report of a potential electrical arc or short was scrutinized. As the “on call” NTSB systems investigator in September of 1999, I was dispatched to examine a Delta Air Lines MD‐88 that performed a precautionary landing near Cincinnati, Ohio, after declaring an emergency due to a cabin fire. The flight attendants reported that there was a sulfurous smell followed soon after by smoke in the forward cabin. During the descent to land, a flight attendant discharged a Halon fire extinguisher into a floor grill where she saw a flame.

The MD-88 has two heater plates on both sides of the fuselage that are flush-mounted against the static air pressure sensing ports to ensure that the ports do not become blocked by ice (top image page 40). The heaters are powered by 115-volt alternating current through a 10-ampere circuit. The investigation revealed that a spark from the right static port heater plate ignited a small fire that propagated by consuming the sidewall insulation blankets surrounding the heater (lower image page 40). Examination of the heater revealed localized soot on the thermostat case, and on the lead wire that carries the 115 volts to the thermostat. The lead wire was bent sharply around the thermostat case, and its conductor was exposed at the bend (top image page 41) due to a manufacturing flaw. In response to the incident, Delta Air Lines initiated detailed visual, electrical, and functional inspections of the static port heaters on its entire MD-88/MD-90 fleet of 136 airplanes. What they found was frightening: 11 percent of the airplanes had at least one heater installation that exhibited some type of damage. Nine of the heater installations had arced, burned, or melted parts in the area of the electrical connector. Two heaters had charred and exposed elements on the heater plate.

In addition to the Delta MD-88 incident, I investigated another event involving an electrical fire in a World Airways MD-11. A vigilant mechanic at an MRO in California discovered evidence of sooting while removing several floorboards in the MD-11’s cargo hold. A wiring harness was routed onto a frame without the required support bracket/clamp, which allowed a wire bundle to chafe against the frame. The finding led to an FAA airworthiness directive (AD) that required visual inspections of certain MD-11 airplanes to verify that a bracket and nylon clamp were installed to support a specific wire bundle, repair any damage to the bundle, and install a protective wrap around it. Who knows what could have happened if that MRO mechanic ignored this discrepancy.

Rearing its Ugly Head in San Francisco: ABX Air 767-200

The airline industry kept serious wiring issues down to a dull roar during the years immediately following these events. But then, in late June 2008, while filling in for the vacationing director and deputy director of the NTSB’s Office of Aviation Safety, I was notified of an ABX Air 767-200 freighter that experienced a ground fire at San Francisco International Airport just before engine start. The pilots evacuated through the cockpit windows and were not injured, but the airplane’s crown had severe fire damage (see middle image on page 41). I facilitated the launch of a small go-team to investigate the event. I remember thinking: “But for the grace of God that the fire occurred on the ground rather than in the air.”

The 767 was converted from a passenger to a cargo configuration four years prior to the event by a company that performed an STC modification to the “supernumerary” crew seating area behind the flight deck. The STC included flexible hoses for a supplemental oxygen system (see lower image page 41). During postaccident inspections of other ABX Air 767 airplanes that were modified by the same company, some installations were found to have electrical wiring routed above and in direct contact with the oxygen tubing, even though the STC provided for positive separation. The investigation of the fire aboard the accident airplane found that a short circuit from electrical wiring was the most likely source to energize a coil spring inside an oxygen system hose, causing the hose material to ignite.

Advisory Circulars 43.13-1B and AC 65-15A state that no electrical wire should be located within ½-inch of any combustible fluid or oxygen line and that, if the separation is less than 2 inches, back-to-back clamps or a polyethylene sleeve should be installed to ensure positive separation. However, this guidance was not followed in the installation and inspection of the STC in the ABX Air 767, and a fire ensued.

History Repeats Itself: A Piper Cheyenne II in-flight fire.

Later in my career, while serving as the director of FAA’s Accident Investigation Division, another accident occurred due to the lack of separation between electrical wiring and other systems. On July 29, 2016, a Piper PA‐31T Cheyenne II twin-turboprop — while operating as an air ambulance — broke up in flight over McKinleyville, California shortly after the pilot reported smoke in the cockpit. The pilot, two medical personnel, and the patient were killed.

The wreckage was located several hours later in heavily forested terrain. Portions of the burned and fragmented wreckage were scattered along a half-mile debris path. The center fuselage and cockpit areas were largely intact and displayed no evidence of fire (see top image page 42); however, a large area of thermal damage to the forward fuselage and circuit breaker panels were found. An aluminum stringer in this location exhibited “broomstrawing” indicating that it was heated to near its melting point prior to impact. A single wire located in the area exhibited “notching” consistent with mechanical rubbing (see lower image page 42) and exhibited evidence of electrical arcing. Four hydraulic lines servicing the landing gear were located in this area, and all the lines were partially burned, melted and missing sections of material.

Prompted by these disturbing findings, six other airplanes of the same make and model were examined.

Sure enough, they all had instances of electrical wires and hydraulic lines in direct contact with each other in the area of the main bus tie circuit breaker panel. Some of the wires were chaffed. The NTSB stated the cause was: “An inflight fire in the floor area near the main bus tie circuit breaker panel that resulted from chafing between an electrical wire and a hydraulic line and/or airplane structure.” But even before the cause was determined, the NTSB issued an urgent safety recommendation to address the unsafe wiring conditions. The FAA quickly issued an AD that required repetitive detailed visual inspection of the wiring below the circuit breaker panels in Piper PA-31T series airplanes.

Prevent Fires by Checking Wires

The lessons learned from these accidents and incidents are plentiful. If you are a maintenance professional who wants to prevent opportunities for aircraft fires, you need to heed the guidance from the FAA and the manufacturer. More importantly, if you “see something” similar to the items listed below, then you need to “say something” so that an electrical fire can be prevented:

• No wire should be located within ½-inch of any combustible fluid or oxygen line.

• If the separation is less than 2 inches, back-to-back clamps or a polyethylene sleeve should be installed to ensure positive separation.

• To prevent chaffing, wiring harnesses should not be routed onto a frame without the required support bracket/clamp.

• Generally, clamps should not be spaced at intervals exceeding 24 inches. In high-vibration areas or areas requiring routing around structural intrusions, the clamping intervals may need to be reduced in order to provide adequate support.

• Routing of wires with dissimilar insulation, within the same bundle, is not recommended.

• Accumulation of dirt and lint near electrical wires creates a potential for smoke and fire.

• The minimum radii for bends in wire groups or bundles must not be less than 10 times the outside diameter of their largest wire.

• Metal stand-offs must be used to maintain clearance between wires and structure. Employing tape or tubing is not acceptable as an alternative to stand-offs.

Many wire defects may be difficult or impossible to detect through visual inspection alone, automated test equipment (ATE) inspection systems are available to supplement visual inspections. These systems include electrical continuity or resistance tests, insulation resistance and capacitance tests, and time-domain reflectometry (TDR).