FARs vs. Consensus Standards

Part 2: Manufacturers’ Authority Under the ASTM Light Sport Consensus Standards vs. the FARs

Although there is less legal conflict between the ASTM Consensus Standards and the FARs as to when prescribed maintenance and inspections must be undertaken, some S-LSA manufacturers have muddied the waters with regard to inspections, at least, by publishing manuals that contain annual condition inspection and 100-hour inspection checklists that are not the same. This creates legal problems for AMTs and safety concerns as well. Here’s why.

FAR 91.327 imposes operating limitations on S-LSA aircraft. One of these requires that the aircraft be inspected according to procedures developed by the manufacturer. The regulation goes on to prescribe two circumstances in which inspections must be accomplished: the annual condition inspection and, for S-LSA used for compensation or hire, the 100-hour inspection. Although F2626 defines the 100-inspection to be the same as the annual condition inspection except for the required inspection intervals, some manufacturers’ 100-hour inspection checklists are an incomplete subset of inspection tasks contained in the annual condition inspection checklists. This makes the “time in service” inspection less than complete than the annual inspection, contrary to both the ASTM definitions and the FARs.

Many S-LSA owner/operators, and many AMTs working on these aircraft, understandably take the manufacturers’ inspection checklists as gospel and follow them, thereby creating potential safety as well as legal problems for themselves. Although the scope and detail requirements of Appendix D of Part 43 do not apply to the inspections of S-LSA aircraft, a complete inspection of the aircraft is required at each prescribed inspection interval.

There is one instance in which manufacturers can say when. That is in issuing instructions for continued safe operation of the aircraft in the context of Safety Directives, as authorized implicitly by both the ASTM standards and FAR 91.327.


Finally we come to the topic upon which everyone is agreed: the how of S-LSA maintenance. The manufacturers are entitled, in fact legally required, to develop and make available maintenance manuals, instructions, Safety Directives, and other such guidance to owner/operators and maintenance personnel to enable their products to be continued in a condition for safe flight. These requirements are found in FAR 91.327 as well as in the ASTM Consensus Standards themselves. Thanks for this area of agreement at least!

In doing so, however, so the FAA lawyers say, S-LSA manufacturers are not permitted to impose training, experience, or certification requirements beyond the requirements of the FARs, as already discussed.

What’s an AMT to do?

First, don’t panic and decide to stay clear of S-LSA aircraft and the world of the ASTM Consensus Standards. Embrace the opportunity presented by this new segment of the aviation maintenance industry, as encouraged in my original article. Follow developments as the controversy surrounding these issues is resolved by future developments. And follow these additional guidelines:

1. Make sure you have the current manufacturers’ maintenance materials and follow them, and have the task-specific experience required by Part 65, just as you would with Standard Category aircraft maintenance.

2. Perform all required condition inspections (whether on an annual requirement of when or 100-hour requirement of when) with the same scope and detail contained in the manufacturer’s condition inspection checklist, even if the published 100-hour checklist is abbreviated, and be sure that you are always conducting a complete inspection, sufficient for you to confidently return the aircraft to service in a condition for safe operation.

3. Comply with the manufacturers’ training and experience requirements, even if different from or more extensive than that required by the FARs, if economically and practically feasible. Make sure you always follow the current manufacturer’s maintenance instructions, including utilizing the required tools and equipment (or their equivalent). Ref FAR 43.13.

4. Pay particular attention to continued safety information such as Safety Directives, as well as the Airworthiness Directives and published Airworthiness Limitations for all FAA-approved components incorporated into the aircraft.

Stay tuned!

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