By Sarah MacLeod, Executive Director, Aeronautical Repair Station Association
What is a “DER” repair? The U.S. regulations require all maintenance be performed in accordance with methods, techniques, and practices acceptable to the FAA. Other civil aviation authorities have a similar or the same quality standard.
Under the American rules, if the method, technique, or practice results in a major repair or alteration, persons performing and approving the work for return to service must do so in accordance with “applicable approved technical data”.
So, what is technical data and how does it get approved? To answer the first question, you must understand the second. Engineering data gets approved under 14 CFR part 21 by either the FAA or a designee of the administrator under part 183.
Designated engineering representatives (DERs) are authorized to approve “engineering information” that s/he has determined complies with the applicable regulations. Section 183.29 outlines eight engineering disciplines under which an engineer may obtain authorization, which is further explained in various orders, notices, and policies established by the FAA. Designees serve at the pleasure and sole discretion of the agency; a privilege that can be removed at any time for almost any reason.
A number of the orders, notices, and policies explain that technical data is really engineering data since that is the information used to determine compliance with the “applicable regulations.” For repairs the “applicable regulations” is a bit misleading as it means different regulations to different folks.
Maintenance must follow the methods, techniques, and practices needed to return the article to at least its “original or properly altered condition.” Designated engineers must find compliance with the applicable airworthiness standards, like parts 23, 25, 27, and others that relate to the aircraft, aircraft engine, propeller, or appliance. The original condition is dictated by the type design, which was found to comply with the applicable airworthiness standard.
DERs with “major repair” authority are to review the repair instructions (the methods, techniques, and practices) to ensure the original or properly altered condition will be achieved when the steps are performed properly. The DER must know and understand the technical data, i.e., engineering information, associated with the original or properly altered condition. However, a repair does not return something to a new, unused condition.
Often the new, unused standards are used rather than the condition expected of an article that was designed to experience wear and tear. Provided a repair action, whether major or minor, returns an item to a condition anticipated and expected by the design, the proper result has been achieved under the maintenance regulations.
While major alterations have different issues when it comes to engineering information and technical data requirements, the regulations are constructed to ensure a proper analysis. The definition of a minor repair in § 1.1 is one that is not major. That means a prudent maintenance provider will gather the data necessary to establish the repair is not major. Furthermore, if the technical data must be approved, the appropriate DERs (and there may be a need for more than one discipline) can be provided the appropriate information.
Knowing these details helps maintenance providers make proper determinations – and follow proper procedures – for enlisting DER assistance. Those procedures must include appropriate documentation should there be future questions regarding major repairs.
Sarah MacLeod is managing member of Obadal, Filler, MacLeod & Klein, P.L.C. and a founder and executive director of the Aeronautical Repair Station Association. She has advocated for individuals and companies on international aviation safety law, policy, and compliance issues since the 1980s.
