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Missing an FAA Form 337


While onboarding one of our recent customers, we were curating their maintenance tracking profile when we noticed they were overdue for Ignition switch AD 76-07-12. Their most recent AD compliance report stated that it was recurring and still being complied with, however after a little bit of digging, this AD no longer applied to our client’s aircraft.

This AD refers to Bendix ignition switches only. Our customer had their Bendix switch replaced in March of 2018 with a brand new ACS switch. The customer’s mechanic stated in a maintenance entry in March of 2018 “Replaced engine ignition switch and installed ACS ignition switch P/N A-510-5 NSN IAW Beech Bonanza M35 MM 35-590096 REV B22.” After looking up the part number on the ACS website we discovered this on the Aircraft Spruce page: 

We confirmed via phone call to ACS, that this part is not approved for certified/production aircraft and must have a Form 337 filed with the install in non-experimental. Had the A-510-2 been installed, the 337 would not be required. After further investigation into the clients documents and maintenance entries, we discovered that they did not have a 337 for this part on file with us, nor was a 337 for this part mentioned anywhere in the maintenance entries.

The client had an FAA CD on file with us however, it was from 2013. We can’t say for certain that the client’s mechanic filed a 337 for this part with the FAA, and we certainly don’t want to assume so. We went ahead and ordered a new FAA CD for the client to investigate further.

This is a great example of how beneficial our service can be for the GA community. What seemed to just be an overdue AD quickly turned into a possible improperly installed part after only a few minutes of research done by our team. We were able to quickly and accurately search the part number to find when it was installed and if there was a 337 filed with it. Catching something of this magnitude that was installed 5 years ago shows how easy it is to mistakenly be out of compliance. We advised our client to have their mechanic file a Form 337 with the FAA for this part to resolve the issue if we are unable to find evidence that one was already filed when we receive the new FAA CD.