First, I am an expert on nothing.
Second, I have more than a passing interest in the subject of missing 337's.
I have talked briefly with Charles about this in the past and I'm sure he can, if he wishes, clarify the subject.
FAR Part 43, Appendix B says in part:
(b) For major repairs made in accordance with a manual or specifications acceptable to the Administrator, a certificated repair station may, in place of the requirements of paragraph (a)-(requirement for 337)-
(1) Use the customer's work order upon which the repair is recorded;
(2) Give the aircraft owner a signed copy of the work order and retain a duplicate copy for at least two years from the date of approval for return to service of the aircraft, airframe, aircraft engine, propeller, or appliance;
Of course it is necessary to examine the regulations in effect at the time of the repair. From this reading it appears that a certificated repair station does not need to file a 337 and they only need to keep records for two years. Now if a past owner chooses not to include the work order in the records passed on when the plane is sold, the only record may be a return to service or annual from a certified repair station.
It sucks but I would guess that it is not an uncommon situation and is only now coming to light with computerized records available from the NTSB and FAA regarding accidents or incidences and our access to the 337's filed with the FAA.
Harry
