Tag: Featured Story

TYING EVERYTHING TOGETHER BY HELPING ELECTRICAL AND ELECTRONIC SYSTEMS COMMUNICATE AMONG DIFFERENT DEVICES.

Aviation wiring, connectors and interconnects seamlessly transmit power and data to connect electronic and mechanical systems, including everything up to mission-critical systems and flight controls. These components form an electrical wiring interconnect system (EWIS) rather than a conglomeration or assembly of individual components. This system can be likened to an aircraft’s central nervous system — making sure the correct information is received at the right place at the right time.

Jeff Behlendorf, director of product management at Amphenol-CIT, Franklin, Wis., says it’s the wiring that ties diverse aircraft systems together. “That wiring comes in a wide range of forms specifically designed for aviation use and tested to assure reliability, safety and signal integrity.”

Wiring is selected and sized to transmit power or data while maintaining safe operating conditions (below maximum rated temperature, operate within verified voltage limits, etc.) and minimizing signal loss. Chris Wollbrink, engineer at Lectromec, Chantilly, Va., explains that wiring serves a similar purpose to the central nervous system (signal wires) and cardiovascular system (power transmission). “Signal wires transmit data and tell operators and equipment about the aircraft condition, while power transmission wires respond to inputs from the pilots and computers. This is analogous to our nervous systems communicating with our brains and our muscles responding to stimulus or commands.”

Connectors provide an interface between the wiring and the system components, such as fans, relays, actuators, computers, radios and displays. “Connectors are generally designed to be connected and disconnected easily to allow service and replacement of these system components. Interconnects often provide a similar function, but are often semi-permanent connections and not designed for regular disconnection,” Behlendorf says. Connectors and interconnects can even provide environmental protection from moisture and aviation fluids.

Wollbrink says connectors and interconnects serve as terminations in the wiring to maintain harnesses and minimize the amount of wiring that must be replaced during inspections. “Connectors are enclosed devices that serve to protect pins from the environment and unwanted pin contact. Interconnects are a more general overarching term, of which connectors are a part of. Interconnects include, but are not limited to, terminal blocks, bus bars, and structure bonding.”

Maintaining and Repairing

Maintenance and repair of aircraft wiring and associated components require skilled technicians and the right tools. But Christopher Ericksen, global product specialist at W. L. Gore & Associates, Inc. Newark, Del., says the first line of defense is a good offense, meaning that products “should be designed with potential failure modes in mind and preventative features such that the need for maintenance or repair is minimized or eliminated altogether. If it cannot be designed in, due to various other requirements (including weight), then the next option would be to train installers and maintainers in best practices. For repairing, designing systems with field-replaceable components or sacrificial components in areas that are most susceptible to damage. Service loops can be used to make sure there is additional length in order to re-terminate connectors onto the cable.”

For wiring and connectors/interconnects acting as one solution or a cable assembly, maintenance usually means removing the assembly from the aircraft when end of life is reached and replacing it with a new assembly. However, if field repair is necessary, certain manufacturing techniques for cable assemblies like wiring service loops and signal/wiring redundancy can be applied to the connectors/interconnects.

For example, Matthew McAlonis, engineering fellow, Aerospace TE Connectivity, Berwyn, Pa., explains a wire service loop adds extra length at the rear of the connectors. “If the connector’s contacts are damaged and need re-termination, the wire service loop’s extra length will accommodate this repair while also allowing the cable assembly’s intended overall length to be maintained. Another example is if the connector is connected and disconnected at a high cycle rate (500 cycles), wear and tear on connector threads and contacts can occur. To overcome this, a connector saver can be used. Connector savers are easy to replace and save on the cost of rework.”

To repair connectors, often they have to be disassembled, pins extracted and terminations replaced to troubleshoot wiring problems. Most aircraft wiring uses crimp termination methods, which can be done with hand tools and the correct dies to match the contacts.

“Some specialized terminations, such as Ethernet cables, require careful attention to make sure the wire twist is preserved and the relative wire lengths are consistent between pairs,” Behlendorf says. “Coaxial cables for antennas on the aircraft have complex multi-layer strip requirements, which may be assisted by specialized stripping equipment to assure no damage to the wiring when removing jackets and shields. Be sure to know what the right tools are for the connectors and wires you are maintaining and the job will be much easier and the finished work more trouble free.”

For part 25 aircraft, all EWIS components are subject to regular inspection. At the OEM level, Wollbrink believes the best solution for maintaining EWIS is by designing a system with high accessibility and that accessibility coupled with selecting the correct EWIS components for the application are critical. “To minimize the aircraft downtime to service EWIS components, accelerated aging techniques can be used to determine the reliable service life of candidate components; these aging tests generate data to determine how well the components will fare in the harsh environments that EWIS components experience. Basic electrical thresholds must be maintained based on specifications and standards as well.”

Wollbrink adds that for maintainers, repairing the EWIS following accepted industry guidance, such as ASTM F2799 and/or the manufacturer’s guidance is the best approach. “For inspection, guidance from FAA AC 25.27A and MIL-HDBK-522 provide a great basis for what should be caught during routine inspections.”

EWIS Special Factors

A complete aviation solution should have robust wiring, connectors and interconnects that can withstand harsh and hostile high-altitude operating environments. Additionally, the end application can drive specific requirements for performance at demanding high/low temperatures, mechanical strength in high-vibration environments, meet military specifications, etc. Materials and constructions are selected and tested to make sure wire connections remain reliable even as parts freeze, thaw, bake, expand, contract and shake during a flight. “Commercial aircraft require flight controls with the most rugged and durable connectors to perform within extreme temperature fluctuations of +50°C while on a hot tarmac to –60°C while at in-flight altitudes,” says can bu. “Components must also withstand repetitive high use in commercial applications.”

Vibration, chemical exposure, salt fog, sand/dust/dirt contaminates and other factors are well documented in the MIL-STD-81490 for Airframe Cabling. FAA regulation 25.1703 dictates wiring, connectors and interconnects shall be qualified to the installation environment and must operate appropriately in that environment. However, Wollbrink explains with the advent of EVTOLs, which, right now, do not fall under part 25 regulations, definitions have become problematic. “The current generation of EVTOLs operate at higher voltages (currently between 600-1000 Volts), which has been a topic of much discussion among the certification authorities and standards organizations.”

Reduced Size and Weight

Aviation parts manufacturers are always looking to find ways to make their solutions lighter and smaller. Material set selection is critical to reducing the size and weight of interconnects while not sacrificing electrical or mechanical integrity and robustness.

For example, Grant Lawton, application engineer at W. L. Gore & Associates, Inc., says that by choosing an optimized insulative material one can decrease conductor size without compromising performance. “When down-gauging conductors, special attention must be paid to mechanical strength and performance over temperature. Robust testing and qualification are important to evaluate that performance has not been compromised as we reduce size and weight. High-strength material sets have driven size and weight decreases while meeting or exceeding aerospace industry requirements. System driven increases in bandwidth and frequency range have driven the need for higher performance interconnects that not only must function ‘out of the box’, but after installation, and over time.”

Wollbrink says a common change that he has witnessed is the incorporation of aluminum conductors and smaller connectors. “These components must undergo much of the same testing as existing components to ensure that they will be able to handle the environments that they will be installed in. Aluminum conductors have become more prevalent in aircraft despite their lower conductance and malleability when compared to copper. Techniques to increase flexibility via smaller strand thickness and braiding techniques have allowed aluminum conductors to be more resilient and competitive to their copper counterparts.”

Carbon-nano tubes have made significant progress in the last decade, which could contribute to saving weight as well. Wollbrink notes that carbon nanotubes will need further testing to become applicable for high performance electrical cables but will reduce the weight currently occupied by copper and aluminum.

EWIS Evolution

High data and power management has created EWIS needs. Modern aircraft use five times as much electrical power as it did just a few decades ago. McAlonis says that makes power switching systems with embedded sensors and electrical monitoring equipment more vital than ever to improve efficiency and load balancing. “Fiber optics and nano miniature connectors in navigation and communication systems also allow faster data transfer.”

The industry has continued to push for higher data rates, higher voltages and higher operating temperatures as aircraft manufacturers increase the sophistication and performance of their new aircraft designs. Behlendorf says this has created “material innovations like composite connector bodies, ceramic insulators, electroplated polymer shields and a wide range of advanced flouropolymers used in components. Environmental regulation has also driven some innovation, evolving fire retardants, platings and base metals used in components.”

Improved EWIS Signal Integrity

Signal integrity has continued to improve having received increased attention through enhanced performance requirements. Patrick Jemmi, application engineer at W. L. Gore & Associates, Inc., believes “The more we test, the more we learn and improve. The prevalence of sensors, increased data rates/frequencies, and overall information has empowered AI decision-making capabilities. That data flows through the interconnects. Maintaining the interconnect signal integrity is critical to AI making the correct decisions. Typical electrical parameters such as power, loss, shielding effectiveness, crosstalk, and phase matching/tracking all contribute and are important to evaluate. Fiber optics can help system performance, versus copper, by minimizing loss, eliminating shielding effectiveness concerns, and having extensive bandwidth while significantly reducing size and weight.”

Because EWIS quality and reliability is so critically important to flight system management, Behlendorf believes the industry has tightened manufacturing tolerances to achieve higher data rates in the challenging aircraft environment. “This includes adapting fiber optic technology to the aviation market as well. Aviation fiber is very different from telecom fiber and uses a unique jacketing and termination system in order to tolerate the changing temperatures, pressures and vibration on board an aircraft.”

In addition to its smaller size, signal integrity and weight advantages, fiber is inherently immune to EMI and crosstalk issues, has massive bandwidth over significant distance compared to copper, and typically weighs much less. Cables are typically smaller because they do not need the electrical shield layers that add to both weight and cable diameter.

FAI Technik is a 100% subsidiary of FAI Aviation Group Holding, which has been in business for more than 30 years and, since 2017, has had a partner in Mumtalakat, the sovereign wealth fund of the Kingdom of Bahrain.

The primary aim of the company is to support sister company FAI rent-a-jet which has five Bombardier Global Express and one Challenger 604 for charter work (the largest Bombardier fleet in Germany) and five Bombardier Challenger 604s and four Learjet 60s for air ambulance operations.

At its highest point, the fleet totaled 29 aircraft (including air ambulance) but there has been a switch to longer range operations and a restructuring, including the retirement of nine Learjet 60s. As a result, Global Express operations saw revenue increase by 22.24% in 2023 over the previous year, with the US becoming the top destination country (from number 10 in 2021). Newark and Los Angeles were in the top seven destination cities last year.

Longer flights mean more flight hours, around 11,000 in 2023, accelerating maintenance requirements. These are further boosted by the company’s active promotion of aircraft availability. Most flights are one way, so, as soon as a booking is made, details of where and when the aircraft is next available are put online for brokers to see. In this way, 80% of flight time is utilized for carrying passengers, which is higher than some other major charter operators’ live utilization. The same method is used for air ambulance flights, also with success.

In fact, the highest utilization still comes from the air ambulance Challenger fleet. As an example, between Auust 6-16, one flew Nuremberg-Al Ain-Bangkok-Tokyo-Anchorage-Toronto-Puebla, Mexico-St John’s-Nuremberg, racking up around 46 flight hours and covering 23,389 Great Circle miles, just short of the Earth’s circumference at the Equator. This is fairly typical, requiring flight crew and medical crew changes en route as duty times expire.

Facilities

FAI Technik has a 14,000 m² carbon-neutral operation with 70 people in three hangars in Nuremberg and a further 30 people in over 3,400 m² of hangar space and another 1,300 m² of workshops, stores and offices at Berlin Brandenburg Airport.

Nuremberg can carry out heavy checks on all types of aircraft. About 50% of the work is for third party, helping towards expected 2024 revenue of €30 million, with VistaJet Malta being a frequent customer, while also being a competitor on the spot charter market.

In fact, it recently carried out a 7,800-landings check on a Challenger 604, one of the most extensive for the type. This involves removal of most of the main aircraft parts and components, including engines, APU, thrust reversers, interior, forward and aft fuselage fuel tanks and the majority of flight controls, much of which is not involved in the 48-and 96-month checks. Non-destructive tests (NDT) such as X-ray, ultrasonic, eddy current and magnetic, comprise up to 30% of the inspection tasks.

Engine overhauls are subcontracted to Lufthansa Technik Aero Alzey and Pratt & Whitney in Germany and to other overhaul facilities in the U.S.

The Berlin facility opened in February 2023, operating from Beechcraft Berlin Aviation’s former base which filed for insolvency in spring 2022. Over 90% of the former workforce was reemployed by FAI. It offers line and base maintenance for Hawker HS125 series, Beechcraft Premier 1/1A and King Air series aircraft as well as line maintenance checks up to 1C for Gulfstream models including G280, G450, G500, G550, G650 and G650ER (although demand is very low at the moment). Additionally, there is an AOG-team for Learjet and Bombardier to support FAI´s own fleet.

Design Projects

The company also undertakes its own design projects but uses a network of specialist partners with Part 21G/J production/design approvals to turn its concepts into a certifiable reality. Two frequently used Part 21J partners are S4A in Spain and QCM in Switzerland. A similar network is used for material and equipment suppliers for cabin reconfigurations.

One of those cabin reconfigurations was Project Pearl, a nine month project in 2020 that also included 60-, 120- and 240-month maintenance inspections on a Global Express. It was led by German designer Tim Callies, who is well known for Airbus ACJ, Boeing BBJ and Bombardier Global Express interiors. It introduced the Collins Aerospace Venue cabin management system and Honeywell Ka-band Ultra High Speed Internet. A 12-seat cabin featured two tone-leather seating, with two three-seat sofas covered in fabric from Armani. Additional modifications and upgrades included new cabinetry, cobalt black metal plating, granite tabletops, a wine cooler, coffee maker and oven in the galley and heated stone floors in the galley and toilet area. This was complemented by a dramatic exterior paint scheme.

On the air ambulance side, the Challenger 604 presents a significant challenge for crews when loading and unloading a patient due to the height of the door sill. Without suitable loading aids, this process also involves various risks for the patient.

Before the COVID-19 pandemic, FAI had a stairlift for all Challenger 604s, which was carried as needed. With the increased use of Portable Medical Isolation Units (PMIU) during the pandemic, it became necessary to have a fixed loading aid on each aircraft. However, procuring additional stairlifts was not possible due to the lack of availability on the market.

This prompted FAI, in collaboration with a metalworker, to quickly design and manufacture an aluminium loading ramp. Within just two weeks, the first prototype was adapted and optimized for the Challenger 604. Two weeks later, the first operational version was available and in use. Subsequently, three more loading ramps were acquired. A ramp is now deployed on every Challenger mission. This is important as there are occasions when a patient is transferred to another aircraft to continue their journey, what the company calls a “wing to wing.”

The ramps, with a total length of 600 cm and a width of 60 cm, consist of four individual parts that are assembled before use.

They offer a number of advantages:

• Smooth transfer of patients from the ambulance to the air ambulance (and vice versa) using a stretcher, without unnecessary movement or lifting of the patient.

• The stable construction and non-slip surface ensure maximum safety for patients and medical staff.

• Flexible use due to easy assembly and disassembly thanks to the modular design.

In addition to patient transfer, the ramp also facilitates the safe loading and unloading of medical equipment or PMIU.

Once on board the aircraft, the patient is moved to a Spectrum Medical Module 2800-XXX Med Base for the flight. Depending on their condition, they will need a range of medical support devices. These are mounted on another FAI design, the Med-Wall, which was developed over a period of almost two years, once again in collaboration with a metalworker. During this phase, several prototypes were created, tested, and continuously refined.

The focus was on various aspects:

• Lightweight construction.

• Universal applicability across all aircraft types.

• Secure and practical mounting of medical devices.

• Effective illumination of the treatment area.

• Functional use of infusion systems (including infusion holders).

• Safe storage of oxygen bottles with direct access.

• Optional mounting of non-standard equipment.

• Sufficient power supply.

The final prototype was approved for all aircraft types via a minor change and all FAI air ambulance aircraft have been equipped with a uniform setup that ensures the highest standards of safety and functionality.

Challenges

Siegfried Axtmann, FAI’s chairman and founder, says much lower business aircraft production rates, compared to those of commercial aircraft, is one of the biggest challenges to finding spares, further hindered by equipment suppliers tending to stop production soon after the OEM stops. Small numbers also lead to delays as the suppliers wait until they have an economical batch size to start repairs. In the case of windscreens (which have seen a 100% increase in price) and lavatories, this has even led to aircraft being temporarily grounded.

As a result, to ensure stock availability, FAI started to tear down aircraft a few years ago. At present, it has 2.5 Learjet 60s, two Challenger 604s and a Global Express disassembled in stock. This also provides another revenue stream, as it can sell parts and lease engines and APUs to other operators.

Another challenge, he adds, is finding personnel to expand, as every MRO is looking for engineers at present. The company is reaching out to schools and universities to attract new recruits.

Have you ever wondered how it would be to fly like a king? One lucky person had a chance to find out. On January 8, 2023, an anonymous bidder ponied up $260,000 for a 1962 Lockheed 1329 JetStar. This was not just any JetStar. This treasure once belonged to the King of Rock & Roll, Elvis Presley. One peek inside is like being sucked into a 1970s vortex of opulence and luxury. Elvis spared no expense when speccing out the cabin of his last private jet. Red velvet chairs enveloped passengers as they ran their toes across matching red shag carpet. Guests could plug into headphone ports with audio controls and dispense their cigar ash into gold-plated ashtrays. Someone turns on the wall-mounted television and drinks are served from the galley, which also has a Kenmore microwave.

The Lockheed JetStar introduced the world to the corporate jet in 1957. Presley’s ‘62 model likely began flying upper managers back and forth to meetings and treating executives to golf outings on the weekend. They relaxed in tan leather seats and drank scotch from crystal glasses. While visiting airports with my dad in the 1970s and ’80s, all the private jets carried the same aesthetic: non-descript white fuselage, analog cockpits and tan interiors. The King was not having it. As new owners tend to do, Elvis put his stamp on this airplane.

All right, maintainers, listen up; this is for you. At some point in your career, a corporate jet owner will approach you in the hangar and say, “You know, NOU812 is going down for a gear replacement in June. I have been thinking about upgrading the cabin, and this looks like a good time to accomplish that. Get me some estimates, and I will think about it.” Congratulations, life just threw you a curve ball. Don’t sweat it, though; we have people who can help. I have scoured the country looking for some of the best and brightest to formulate a plan and for the new technology available now, which is mind-blowing. Let’s get into it.

Plan of Attack

Before we begin, you need to understand the magnitude of business aircraft interior refurbishment. Why is this important? Let’s break down the numbers with Fortune Business Insights, which recently stated that “the global business jet market size is anticipated to grow from $45.9 billion in 2024 to $66.97 billion by 2032, at a CAGR of 5.4%.” Concerning the aftermarket, Fortune highlights that “fleet modernization programs by developed and emerging economies are anticipated to improve fleet capabilities and generate demand for new charter services with enhanced cabin interiors.” Cabin interiors are big business.

You will need a plan. Start with the client in mind. Remember that the jet owner and guests spend most of their time here. Sure, they will take a cursory look at the engines and may glance at the new flat-screen avionics in the cockpit, but the cabin is how they connect with their airplane. What do they want? I recently caught up with Janine Iannarelli, owner of Par Avion Ltd., an international aircraft marketing firm specializing in representing and acquiring pre-owned business jets. We discussed what aircraft owners today expect of their cabin layouts and amenities. She states that “updated cabin management systems [CMS] are a game changer. Especially among legacy aircraft, when entertainment systems become antiquated, it is not as simple as a plug-and-play solution for monitors, etc. Compatibility is the problem and migration to a newer generation CMS is more and more becoming the only solution.”

Sounds easy, huh? With a solid game plan, sufficient resources and maybe a little luck, you can satisfy the owner and not break the bank. Steve Martinez owns Aircraft Custom Interiors (ACI) in Dallas, Texas. Three miles west of Love Field (DAL). He and I recently connected and I asked him about managing an aircraft interior business. “Everything starts with an idea,” Martinez says. “Our job is to capture the owner’s idea and form that into a workable plan.” This typically begins about six months before the first panel is popped off the sidewall.

Meghan Welch, director of paint and interior sales at Elliott Aviation, echoes that sentiment. “Everything centers on the client relationship.” This week, she and I spoke for a few minutes about the customer experience, and she offered the following insight: “At Elliott Aviation, we go the extra mile to please the customer. I like to have them visit the Moline, Illinois, facility and get to the heart of their wants and needs.” In fact, she was hosting a client onsite the day after our meeting.

Third-party options are great, but only one source will do for some: the factory.

Textron has OEM solutions for overhauling your cabin. When asked about their offerings, Textron replied, “Our company-owned service centers offer factory-designed and engineered interior refurbishments and retrofits to meet the needs of our customers. Popular modifications include custom seating arrangements tailored to the owner’s preferences and LED lighting enhancements that create the perfect ambiance or ensure easy reading. These updates are often seamlessly integrated during major inspections or comprehensive avionics upgrades like the G5000 or Fusion installation.” With cabin MRO options, money and time, nothing is impossible.

Emerging Trends

Corporate aviation is constantly evolving. One of the most important advancements in emerging trends is connectivity. When I spoke with Textron, here is what they had to say: “Cabin connectivity. We understand the importance of staying connected to keep your business moving and turn the sky into your office. In today’s digital age, keeping devices charged is also essential. That’s why we have incorporated high-power USB charging ports into our aircraft and refurbishment options. Productivity and availability are at the forefront when you tap into the air-to-ground capability of Wi-Fi and satellite upgrades from our experts.”

Here are just a few of the connectivity upgrades Textron offers:

• Gogo AVANCE

• SmartSky Flagship

• Airtext+ Cabin Connectivity

At altitude, much of what happens in the cabin is dictated by equipment mounted outside on the aircraft fuselage, and that space is also evolving. Let’s just say there are new tools that allow E.T. to phone home and get a clearer signal. Dave Mellin is the director of public relations and communications for Gogo Business Aviation. Mellin was kind enough to chat with me and bring me up to speed on the latest aircraft connectivity. This is the tale of two satellite systems, old school geostationary (GEO) versus the new kid on the block low earth orbit (LEO).

GEO networks rely on satellites orbiting between 22K and 25K miles. Connecting to the network involves expensive heavy equipment traditionally found on the bigger corporate jets. It is limited by distance and is prone to latency and delay.

LEO systems operate 500 to 750 miles from Earth, which helps minimize the delay. Aircraft can deploy a smaller antenna and operate with smaller systems. The solid-state antenna has no moving parts. Until now, if you wanted in-flight connectivity, you had to compromise based on the aircraft size.

Gogo’s LEO global broadband experience uses the OneWeb satellite network and is designed specifically for business aviation. AVANCE is Gogo’s in-flight connectivity system. The website states: “Gogo AVANCE is not a traditional LRU. It’s a platform. An easy way to understand AVANCE is to think of it like you do Apple. Like Apple and its iOS: the value of the AVANCE platform comes not only from its features, but from its ability to be the central technology that connects to and grows with other tools, innovations, products, and services.” To sum it up, Mellin says the “AVANCE platform future-proofs your aircraft.”

Starlink is an emerging technology that delivers high-speed, low-latency internet access to passengers in flight. They are expanding their supported airframes and going to market through authorized dealers. Starlink’s Laser Mesh Network provides continuous service in areas far from SpaceX ground stations, including polar regions and the open ocean.

One of Starlink’s dealers is Duncan Aviation, the world’s largest privately owned business jet service provider. I fondly recall doing business with Duncan during my stint as a Rotable Exchange Coordinator at Professional Aviation Associates and then as a business owner at Aviation Enterprises, LLC. Last month, Duncan reported installing the company’s first Starlink in-flight internet connectivity system. Work on the Bombardier GL-XRS went smoothly; the Starlink fired right up, and the client “streamed three movies simultaneously and Facetimed with his wife.” The team accomplished the STC job in less than three weeks.

Corporate jet travel is an experience. In the decades since the events of September 11, 2001, commercial air travel has become a bit circus-like. Those with a substantial net worth are immune from such craziness, and rightfully so. Corporations use business jets to move executives, clients, and guests smoothly and efficiently. Time is money, and an hour lost standing in the TSA line is an hour lost closing a big deal. While corporate travel is a step above commercial, truly elite travel is on another level altogether. In this world, luxury is a way of life. Some of you have clients at this level and know precisely what I’m referring to.

Mindy Elizalde is the marketing director of luxury interior specialist Primadonna. Headquartered in Tucson, Arizona, Primadonna is an approved vendor for Gulfstream, allowing clients to upgrade mattress and bedding options. Primadonna’s recent acquisition of SJ Lipkins enables the company to offer a more robust product offering, and the Lipkins cabinet solutions integrate with Primadonna’s flatware and fine china. Lipkins’ signature line is its Cloudstone countertops. The company states they are “lightweight yet durable, solid yet flexible.”

F. LIST (F/LIST) from Thomasberg in Lower Austria, is a global interior supplier for business and private jets. They are expanding the horizon for interior spaces, including dynamic designs using sustainable materials. CEO Katharina List-Nagl recently stated, “For F/LIST, sustainability is at the heart of everything we do as a company, be it in terms of our processes, people, or the products themselves. It is almost impossible to think about a new product or service without considering sustainability.” In late 2023, Pilatus Aircraft Ltd. presented the first use of the bio-based material F/LAB Aenigma in the cabin of a business aircraft. A portion of the F/LIST press release states, “Inspired by F/LIST Shapeshifter, the F/LAB Aenigma opens a new chapter in aerospace materials, presenting an ingenious blend of cutting-edge technology and environmental responsibility.” Innovative companies like Pilatus Aircraft and F/LIST continue to push the industry forward.

Best Practices

Many elements drive the decision to gut the cabin of a corporate jet completely. One such element is a major maintenance event. Maintenance crews often need access to control cables, tubing, or components under the cabin floor or the sidewall. Wiring bundles, torque tubes, and all sorts of mechanical shenanigans are going on, safely tucked away from passengers and crew. When one of those components needs attention, everything in its way is coming out. Now seems a good time to update the cabin. The aircraft is down regardless, and the major maintenance covers most of the labor. Much like the advice I gave my engine shop customers during a sudden stoppage inspection, consider bumping up to an overhaul while insurance covers the labor if your engine has significant time on it.

Let’s head back to Lincoln and talk to Duncan Aviation again. It takes a team to navigate today’s business challenges, and one only gets there by deploying the best practices gleaned from years of effort. I had the pleasure of connecting with two of their refurbishment team, Steve Elofson and George Bajo, to discuss those challenges and how to overcome them. We learned that aircraft connectivity is at the top of many owners’ want lists when planning their new cabin design. Understanding how clients use their aircraft and tailoring a solution to fit that need is mission-critical.

When discussing building the service order, Elofson offered the following:

1. Ask the client where they wish to operate the aircraft. Is their intention to travel outside of the USA? Gogo is now using an air-to-ground (ATG) system, which is very cost-competitive and has good coverage in Canada and Alaska as well.

2. Determine what the client’s operating budget is. Duncan will quote a price for the physical hardware and installation labor, but the client must deal directly with the service providers for the monthly coverage. Each is different and has its pros and cons, such as satellite or unlimited data.

3. Cabin management systems (CMS) upgrades are typically tied to maintenance events, such as heavy checks, engine work, or avionics upgrades. If the crew has to access under the floor or sidewall, the interior seats, panels, and components are coming out anyway.

Once maintenance is in motion, it is imperative to remember that documentation and communication drive facilitation. I asked Bajo about how Duncan best manages this process. He stated that everything downstream is managed by a change order. If the maintenance technicians discover an issue, they document the squawk immediately. This applies to both airworthy and unairworthy conditions. These issues could be minor, like a cosmetic blemish that requires the owner’s attention or as serious as a crack in an aluminum structural component. These findings are posted on findings on the myDuncan website. There, clients may gain additional intel, view photographs of the affected area, and even approve the quote to keep maintenance in motion. This is invaluable as without approval to proceed, some maintenance activity halts. This could impact the lead time on delivering the aircraft. I would oftentimes have to remind my clients at the engine shop that the lead time begins and the time of approval is not the quote date. Duncan has an advantage because of its extensive capabilities; most needed solutions are in-house. Additionally, they deploy a vast arsenal of TSO, STC, PMA, and DER repairs for compliance. This is critical to remember, as deployment can be immediate for off-the-shelf products with approvals in place. If the client requires a custom solution that has yet to be approved, there will be an additional lead time until that happens. Even coffee pots carry FAA PMA approval.

Some aircraft owners are plugged into the latest bleeding-edge technology for their specific platform. Again, I recall my engine shop days when owners would hit me with new whizbang gadgets they read about on a blog post and want me to quote them on working that into their engine overhaul. Unfortunately, I had to break it to them, saying that their engine would lose its certified status unless new technology had FAA approval. Steve and I talked about this as well. He offered the following thoughts. You have to educate yourself to talk with the client about upgrade options. We spoke earlier about emerging technologies, like cabin power. Power outlets at seat locations can now accommodate USB, USBC, and MagSafe wireless charging. Lighting elements can set the mood for the cabin, cool vs warm. 4K display is now a reality. Passengers can consume content stored on their devices or stream it via apps on their devices. The newer technology allows for the use of cabin controls via an iPad with minimal lag.

Bajo and I finished up the conversation with the single most important factor to remember for maintenance providers when managing a cabin interior refurbishment project. He called it: “Get ahead of the jet.” With aerospace supply chain lead times as they are, staying ahead of the game is essential. DOMs track aircraft times and cycles like their life depends on it because it does! It is imperative to know what is coming down the line. Engines, landing gear, and other aircraft components require service at specific flights/times/cycles. By working ahead of the jet, you can advise the owner of when would be an excellent time to set the aircraft down for refurbishment. The time to pick out seat color and material is NOT when they are pulling the seats out. Settle that well in advance.

I closed my research with James Logue, the director of maintenance for Latitude 33 Aviation in Carlsbad, California. We reminisced about the days when business jets were limited to basic Falcon 20s with tan interiors. When the private owner or corporation finished with them, they went to other countries or spent the rest of their days hauling checks. “Things are different these days,” Logue began. “A few years ago, a 15+ year old aircraft would probably finish its life out with the interior it currently had. There was not an ROI to support a full interior refurbishment.” Now that private travel is on the rise, and there is insufficient inventory to meet those needs, older aircraft are holding their value longer. “And now, it makes sense to refresh the cabin,” Logue continues, “and with much of the older factory installed components obsolete, it is necessary to bring the cabin current.” When asked about the decision-making process, Logue says, “The aircraft mission drives the decision.” It is critical to understand how the client will use the airplane and plan accordingly. If you want a deeper dive, check out the Lattitude 33 Aviation article ‘A Guide to Aircraft Interior Refurbishment.’

Former NTSB and FAA investigator Jeff Guzzetti explains how shortcutting the procedure to rig the elevators of a commuter plane led to a tragic accident shortly after takeoff.

As a former aircraft accident investigator, I can attest to the fact that the incorrect rigging of flight controls has led to numerous in-flight emergencies, accidents, and even deaths. Maintenance personnel who serviced or checked the controls did not recognize that the surfaces were moving in the wrong direction. In some cases, the mechanics who performed this work were highly experienced. Anyone can make mistakes, but these mistakes usually lead to tragic circumstances.

Perhaps the most notorious of these types of events occurred on January 8, 2003, when Air Midwest — doing business as US Airways Express flight 5481 — crashed shortly after takeoff from Charlotte, North Carolina. The two pilots and all 19 passengers on board the Beech 1900D turboprop commuter were killed. The National Transportation Safety Board (NTSB) investigation into this crash was intense, complex and comprehensive, and it yielded many lessons learned for airline maintenance professionals.

At the time of the accident, I had recently been promoted out of the NTSB’s Major Investigation Division, so I missed the opportunity to lead the “go-team” in Charlotte. However, in my new role as the head of all NTSB field offices, I closely monitored the investigation and supervised the investigation of a second Beech 1900D mis-rigging event that occurred nine months later.

The Investigation

The NTSB arrived at the Charlotte crash site a few hours after the accident, and their first order of business was to retrieve the “black boxes.” An initial audition of the cockpit voice recorder (CVR) revealed trouble as soon as the landing gear was raised upon liftoff. For the next 26 seconds, the airplane pitched up, stalled, and descended into the side of a hangar, igniting a massive fireball (see graphics 1 and 2).

The final word recorded on the CVR was from someone in the passenger cabin who yelled “Daddy” — a stark and emotional indication of the potential consequences of improper maintenance.

Information from the flight data recorder (FDR) showed that the airplane was rotating nose-up after takeoff, even though the flight crew was pushing the control column fully forward and trimming the airplane in the nose-down direction. This prompted investigators to focus on the pitch control system of the Beech 1900D, which consisted of cables, pulleys and bellcranks connecting the cockpit control columns at the front of the airplane to the elevator surfaces at its tail (see graphic 3).

The pitch control system also included two turnbuckles that allowed mechanics to adjust the position and cable tension of the system (see graphic 4). Examination of the turnbuckles as found in the wreckage revealed that the nose-down turnbuckle, which measured 7.30 inches in length, was extended 1.76 inches more than the nose-up turnbuckle, which measured 5.54 inches in length (see graphics 5). By quickly conducting a survey of its fleet of 42 Beech 1900D airplanes, the airline discovered that these measurements were not normal. The survey results indicated that the nose-down turnbuckle was extended, on average, only 0.04 inch less than the nose-up turnbuckle, rather than the 1.76-inch difference noted in the wreckage.

Investigators quickly learned that the airplane had undergone a “Detail Six” or D6 maintenance check two days prior to the accident at Air Midwest’s West Virginia maintenance station (see graphics 6). FDR data, ground test results, and aerodynamic analysis showed that, before the D6 check, the airplane’s full range of downward elevator travel was available. However, after the D6 check, the downward elevator travel was limited to about seven degrees rather than the 14-15 degrees specified in the Beech 1900D Airliner Maintenance Manual (AMM).

Part of the D6 check involved checking the tension of the elevator control system cables and adjusting the tension if necessary. The mechanic who performed this work had not previously performed it on a Beech 1900D. As a result, he was receiving on-the-job training (OJT) from a quality assurance (QA) inspector for the tasks associated with that part of the D6 check.

The mechanic determined that the airplane’s cables needed to be adjusted because their average tension was too low. He stated that he adjusted the cables and performed some, but not all, of the steps of the elevator rigging procedure. However, whenever cable tension adjustments are made, the entire elevator control system rigging procedure needs to be performed — not just those steps that apply to cable tensioning.

While NTSB could not precisely determine the changes that were made to the elevator control system during the D6 check to restrict the elevator travel, they discovered during ground testing a scenario that was consistent with FDR data from the accident airplane and the physical measurements of the turnbuckles. Specifically, when the rig pin for the aft bellcrank was not removed and the cable tension was released, and then the rig pin for the forward bellcrank was installed aft of the bellcrank arm, adjustments to the turnbuckles resulted in a nose-up turnbuckle length of 5.12 inches and a nose-down turnbuckle length of 7.70 inches. After the aft rig pin was removed, the test airplane’s elevator moved to 7.7 deg. nose-down.

Skipped Steps and Inadequate OJT

Five of the six mechanics who were on duty on the night of the D6 check had worked at the West Virginia facility for less than eight weeks, and none of them had completed training for the D6 check. The mechanic assigned by the foreman to perform the elevator control cable check was selected for the task because he had previously accomplished flight control rigging work on another type of airplane (DeHavilland DHC-8). The QA inspector, who was providing the mechanic’s OJT, stated that he did not think he needed to closely supervise the mechanic because of his previous flight control rigging experience.

The mechanic stated that, before he inspected the elevator control system, the foreman helped him locate the access panel for the forward bellcrank rig pin and the elevator cable turnbuckles. The mechanic also stated that he and the QA inspector discussed the low cable tensions, the need to adjust the tensions, and the steps that could be skipped. The QA inspector then left to attend to other duties, and another mechanic held the turnbuckles while he adjusted them. The QA inspector returned after the rigging work was completed to observe the final check of the elevator control system.

The QA inspector stated that, after he verified that the forward bellcrank rig pin had been inserted, he left the mechanic unsupervised during the elevator control cable inspections and turnbuckle adjustments. The QA inspector indicated that he had to provide OJT to another mechanic and also perform a borescope inspection on an engine.

The Beech 1900D elevator control system rigging procedure did not include provisions for adjusting cable tension as an isolated task. However, the mechanic decided to adjust the cables as an isolated task and, as a result, did not follow each step included in the rigging procedure. The QA inspector was aware that the mechanic was selectively performing steps from the rigging procedure and that he was only adjusting cable tension. In fact, the inspector stated that he did not think the manufacturer intended for mechanics to follow the entire rigging procedure and that the entire procedure had not been followed when past cable tension adjustments were made.

The NTSB opined that the insufficient training and supervision resulted in the mechanic making mistakes that led to the incorrect rigging and the restricted downward elevator travel. If the QA inspector had provided better training and supervision, the likelihood of such errors would have been minimized.

Another Beech 1900D Mis-rigging

Then, on October 16 of that same year, another Beech 1900D was found to have mis-rigged elevator controls. This time, the airplane was operated by CommutAir as Continental Connection flight 8718. As the airplane accelerated for takeoff from Albany, New York, the captain noted that the elevator control was jammed, prompting him to abort the takeoff. Fortunately, no one was hurt, but the Major Investigations Division asked that I dispatch one of my field office investigators to initiate an incident investigation, given the limelight of the fatal Charlotte accident nine months prior.

Examination of the incident airplane revealed that when the elevator trim wheel in the cockpit was positioned to neutral, the elevator trim was actually in the full nose-down position. The incident flight was the first flight after maintenance the day before, in which the elevator trim wheel was removed and reinstalled. The NTSB discovered that part of the work performed on the airplane included removal and replacement of a throttle pin. To accomplish that procedure, the maintenance technician had removed the elevator trim wheel. However, he did not index the elevator trim wheel before removing it, and reinstalled it incorrectly.

To make matters worse, neither the maintenance technician nor the QA inspector performed a functional check of the elevator trim system following the maintenance. Also, NTSB was shocked to learn that AAM had no published procedure regarding the removal and reinstallation of the elevator trim wheel.

Causes, Factors, and Lessons Learned

The NTSB determined the probable cause of the Flight 5481 disaster in Charlotte to be the airplane’s loss of pitch control during takeoff that resulted from the incorrect rigging of the elevator system, compounded by the airplane’s aft center of gravity, which was substantially aft of the certified aft limit. The NTSB also cited numerous “contributing factors,” such as the airline’s lack of oversight of the work being performed at the West Virginia maintenance station, and its inadequate maintenance procedures and documentation. They also cited the QA inspector’s failure to detect the incorrect rigging of the elevator control system, and the FAA’s lack of oversight of the airline’s maintenance program and its weight and balance program. The NTSB issued 14 recommendations to the FAA related to air carrier maintenance programs, including one to prohibit inspectors from performing required inspection item inspections on any maintenance task for which the inspector provided on-the-job training to the mechanic who accomplished the task.

The legacy of Flight 5481 is its clarion call to all maintenance personnel to prevent mis-rigging accidents by heeding the following items:

• Become familiar with the normal directional movement of the controls and surfaces before disassembling the systems. It is easier to recognize “abnormal” if you are familiar with what “normal” looks like.

• Carefully follow manufacturers’ instructions to ensure that the work is completed as specified. Always refer to up-to-date instructions and manuals — including airworthiness directives — when performing a task.

• Be aware that some maintenance information, especially for older airplanes, may be nonspecific. Ask questions of another qualified person if something is unfamiliar.

• Remember that well-meaning, motivated, experienced technicians can make mistakes: fatigue, distraction, stress, complacency, and pressure to get the job done are some common factors that can lead to human errors. Learn about and adhere to sound risk management practices to help prevent common errors.

• Ensure that the aircraft owner or pilot is thoroughly briefed about the work that has been performed. This may prompt them to thoroughly check the system during preflight or help them successfully troubleshoot if an in-flight problem occurs.

Be careful what you ask for. During the pandemic, aviation industry leaders were desperate for traffic to come back. Now it has. Indeed, revenue passenger kilometers (RPK) are forecast to be 4.2 percent above 2019 levels in 2024 and are likely to keep growing for years after that. Ditto for commercial demand.

But there is a sting in the tail. There are not enough new aircraft to support growing demand, and there is a backlog of more than 16,000 narrow- and widebody aircraft. Challenges with aircraft production rates and new engine technologies have exacerbated the supply shortage.

To cope, there are two major approaches.

The first approach is to keep current aircraft in service; retirement rates are projected to be about 24 percent lower from 2024-26 compared to the decade before the pandemic. Keeping aircraft in the air longer will require more maintenance, repair and overhaul (MRO) services to engines and airframes. These are expensive and getting more so: MRO costs have risen sharply over the last five years.

Moreover, this effort could cause ripple effects throughout the value chain. For example, fewer retirements will limit the availability of the used serviceable materials (USM) that are often used to lower MRO costs. Meanwhile, aircraft lessors are responding by either placing aircraft at significantly higher lease rates or extending at attractive rates while avoiding what would otherwise be financially meaningful remarking and retrofit downtime.

Current market conditions will promote continued MRO growth for the next decade, with spend rising to $135 billion by 2034. During the first few years, growth will likely come primarily from the high demand for maintenance on older fleets. Engine MRO could account for the largest share of MRO spending, with demand expected to be particularly strong in the short term as previous generation engines enter major shop visit cycles.

After that, there will likely be a slight growth dip, due to the impact of lower aircraft production rates and deliveries from 2019 and into the pandemic years. Over the whole period, and beyond, MRO will grow simply because the aviation industry is. But there could be wrinkles.

Specifically, elevated fleet ages and the commensurate increase in maintenance needs for older aircraft are not likely to persist. From 2028 onward, we estimate that aircraft retirement levels will return to historic levels — about 2.7 percent of the fleet per annum — bringing down the average fleet age from today’s historic high of 13.3 years to 12.3 years by 2034.

In addition, airlines regularly transport cargo in the belly of passenger aircraft. During the pandemic, to keep trade flowing, cargo airlines converted passenger aircraft to freighters, which helped increase MRO revenues for passenger-to-freighter (P2F) specialists. As international belly cargo capacity continues to recover, P2F conversions have started to fall and this is expected to continue.

The second approach to narrow the gap is to build and deliver more planes. This is beginning to happen. The supplychain disruptions that have hindered production are expected to ease over the next two to three years; we expect total deliveries will increase an average of 4 percent a year from 2024-34. Fleet growth will be slightly slower than passenger travel demand, however, because new aircraft being delivered are larger gauge than the ones being retired.

The introduction of next-generation aircraft and engines will likely influence MRO spending. Many deliveries will consist of aircraft with composite airframes or wings, as well as next-generation engines. New engines entering the market are experiencing more frequent maintenance visits because of the technical and production quality issues that are common with innovation. But once these are solved, the engines are expected to have comparable or lower maintenance costs than their predecessors. Moreover, even though fleet size is growing, demand for airframe services will likely remain flat, because the composite structures of next-generation aircraft require less maintenance than their mostly metallic predecessors.

The picture, then, is multifaceted: more aircraft will mean more demand for MRO services, but each aircraft will likely need less.

MRO providers today are focused on servicing aging fleets, which account for the majority of demand for their services. But they must also build capabilities for the future. A forthcoming McKinsey survey, for example, found that few MRO providers had integrated digital and analytics at scale throughout the organization. Partly for regulatory reasons, the industry is surprisingly reliant on paper-based record keeping, which makes collating and analyzing data difficult.

Digital transformations are not easy; indeed, most struggle. Preparing now is the best way to get positioned for long-term success.

Vik Krishnan is a senior partner in McKinsey & Company’s San Francisco office. Daniel Leblanc is a partner in McKinsey & Company’s Dallas office.