Return to Service and Airworthiness

The story was that an A&P mechanic had been asked by a customer to disassemble, inspect, and repair two high time Lycoming engines that had been laying around the owner’s hangar for some time, and that he wanted to spend as little cash as possible on them because he was considering using them on a boat he was constructing. He did not want any new parts installed and the mechanic was told to use the minimum acceptable wear specs for assembly in order to keep costs low. The mechanic stated that he did in fact use all the old parts simply because they had appeared to be within service limits as called out in the manufacturer’s specifications.

Needless to say, the owner on receipt of the engines from the mechanic, installed one of them in a Cessna aircraft which was involved in an accident when the engine failed in flight and a forced landing was required. There were no injuries to the pilot only damage to the aircraft. The other engine failed while still on the ground and it was taken apart and inspected and found to have similar defects.

After these two failures of one of the engines, and a subsequent inspection of both engines, he was accused by the FAA of improperly rebuilding, repairing, and inspecting the engines.

The owner of course never did install these engines on any kind of boat and the accident and failures occurred some eight months after being returned to the owner. The engines had several inspections prior to the failures. The owner simply denied the story about the use of the engines in a boat although there was some testimony from others about the boat construction.


Emergency revocation

The mechanic appealed from an emergency revocation of his certificate, and had his hearing before an administrative law judge. He had alleged among other things, that since the engines were to be used to power something other than a certificated aircraft there was no jurisdiction to go forward with the case or with any sanction against his certificate. He would maintain that the Administrator had no authority to regulate his repair and overhaul of the engines. A novel defense to say the least. Furthermore, he claimed he did not certify the airworthiness of the engines nor return the engines to service and therefore had no responsibility for the accident. He stated he only signed his name and A&P certificate number after a description of the work.

The hearing officer had little difficulty in dismissing this defense, by stating that when the certificated mechanic signed the engine logbooks with his certificate number he was saying not only that the work was done by him in accord with the requirements of the regulations and the factory specifications, but that this log entry could be relied on by anyone using the aircraft that the engine was installed in, and that the Administrator did therefore have jurisdiction. In discussing this issue with other mechanics I found some disagreement with this part of this initial opinion.

Finally, in an effort to place some misconduct on the owner, the mechanic urged that the owner was required and responsible under FAR 91.165 to insure that the entries in the engine logbook were accurate and therefore was himself in violation of FAR 91.165. The hearing officer felt that there was some merit to this argument of responsibility for the logbook entries under this FAR and that the owner had violated this FAR. The Board however felt that the owner was not technically competent to determine if the entries in the logbooks were accurate and it dismissed this defense entirely.

The initial hearing officer stated however that he did not think that revocation was required in this case. He dismissed the revocation, imposed a suspension instead and a requirement that the mechanic be re-examined on procedures in writing up repairs in logbooks and rebuilding engines … the FAA and the mechanic both appealed this decision to the full Board.



In regard to the mechanic’s defense that he did not return the engine to service, FAR 43.9(a)(4) states in the pertinent part: “The signature (of the mechanic) constitutes the approval for return to service … only for the work performed” … and therefore the airworthiness of the particular item worked on. However, as I was reminded by some mechanics, FAR 43.9(c) has an exception in application for inspections performed in accordance with Part 91. But 43.9(a)(4) refers to all maintenance. Does this mean that inspections for airworthiness are not approved for return to service by the signature alone in the case of Part 91 ops and that a mechanic must affirmatively make the return to service statement? Must there be an affirmative statement by the mechanic that the engine or aircraft is approved for return to service and therefore airworthy? The answer appears to be no.

FAR 43.9 clearly refers to all maintenance and the signature is all that is required. The exception under 43.9(c) is for inspections. Although it appears from FAR 43.11(a)(3) that the signature, certificate number, and kind of certificate held by the person approving or disapproving for return to service, the aircraft, airframe, aircraft engine, propeller, appliance, component part, or portions thereof seems to suggest that a return to service statement is included when performing an inspection. Furthermore, just in passing, note that in the case of a repair station, it must include a written statement specifically approving the repaired or altered item for return to service under Appendix B to Part 43, where a major repair or major alteration is performed.

To put this issue to rest I would quote Bill O’Brien’s statement … he told me at a seminar a few years back (he is now deceased) that the signature of the mechanic is his approval for return to service but only for the work (maintenance) he has personally performed and that is all that is required. Enough said. He also used to say that the IA’s certification of airworthiness at annual inspection was good until the ink had dried.


Board decision

The NTSB re-instated the mechanic’s certificate revocation based on its finding that he was not qualified to hold a mechanic’s certificate. There is no indication that the mechanic ever appealed his case any further. A mechanic who has his certificate revoked can re-apply after the passage of one year.


What to do?

It seems fairly clear, based on the story and the fuzzy regulations, that it would be prudent for any mechanic wanting to exclude an engine he worked on from being used in an aircraft … to clearly say so in his statement that the engine is not airworthy and is specifically not approved for return to service, (in any certificated aircraft). Why he did not do this is still a mystery.


Stephen P. Prentice is an attorney with an Airframe and Powerplant certificate, is an ATP rated pilot, and is a USAF veteran. Send comments to