Originally Posted by
tcasblue
I wonder what the maintenance discrepancies were. That could be a big issue if they were significant and especially if they led to the accident.
From the Rescission Letter linked above:
Condition and Limitation No. 6 states as follows: Collings must maintain all aircraft subject to this exemption in accordance with the—
a. Collings General Maintenance Manual;
b. Maintenance requirements as specified in the appropriate type specification sheet, as amended;
c. FAA-approved maintenance inspection program that meets the requirements of § 91.409(e), (f)(4), and (g); and
d. Appropriate military technical manuals.
Inspection of the engines on the B-17G N93012 established magneto and ignition failures existed. Regarding engine 4, to prevent the magneto “P” leads from separating from the magnetos, someone had attempted to rig the magneto leads in place with safety wire. Inspection and testing of engine 4 left magneto revealed the movement of the safety-wired lead caused grounding to the case, which rendered the magneto lead inoperative. In addition, the right magneto of engine 4 was found unserviceable. The cam follower was worn beyond limits and the point gap was less than half the measurement required by service documents. When tested, the magneto produced weak or no spark to four of the nine cylinders. All spark plugs were inspected and required cleaning and all electrode gaps were out of tolerance; therefore, further engine inspection indicated signs of detonation and associated damage. An inspection of engine 3 showed all spark plugs electrode gaps were out of tolerance, fouled, and revealed various signs of detonation. Further inspection of this engine revealed problems with the cylinders. As a result of these findings and other information, the FAA questions whether the engines were inspected adequately and in accordance with the applicable maintenance requirements.
The discrepancies noted above indicate maintenance, or lack thereof, occurred in a manner contrary to maintaining aircraft in accordance with the General Maintenance Manual (GMM). The GMM incorporates by reference inspection procedures for individual aircraft, as described the Aircraft Maintenance Manuals. See General Maintenance Manual Rev. 1.1 at 19 (Sept. 10, 2017). Moreover, the records memorializing the inspections and maintenance performed on the B-17G lack key information and, in some cases, indicate maintenance was either not performed at all or was performed in a manner contrary to the applicable requirements. See Ground Check Inspection Form #15: Accessory Inspection, Engine Number Four Fourth (25 Hour) (Sept. 23, 2019); Ground Check Inspection Form #17: Ignition System Inspection, Engine Number Four Fourth (25 Hour) at ¶¶ 11-13 (Sept. 29, 2019). In addition, maintenance records indicate the removal of wires and no further repairs or adjustments, even though a wire was burned and arcing. See NL93012 B-17G Flying Fortress Flight Report (May 11, 2019). The same record, as well as a record from the following day, indicates flights with passengers occurred in the aircraft. See id.; NL93012 B17G Flying Fortress Flight Report (May 12, 2019). As a result, Collings did not fulfill the requirements of Condition and Limitation No. 6.