What happened
On Sunday, March 26, 2000, at approximately 12:00 local time, a Socata MS 893 A aircraft, registered F-BTPK, was performing a flight departure from the Saint-Chamond aerodrome in France. During the pre-takeoff checks, the pilot observed a drop of 200 RPM during the magneto 1 test, followed by a similar drop during the magneto 2 test; however, the full-power shutdown test appeared satisfactory.
As the aircraft accelerated along runway 28 for takeoff, engine parameters initially appeared normal. Shortly after liftoff, the pilot experienced a loss of power, engine misfires, and a subsequent complete engine failure. In an attempt to maintain airspeed, the pilot initiated a right-hand turn. During this maneuver, the aircraft reached an attitude of approximately 40 degrees of bank, causing the right wingtip to strike the ground. The landing gear collapsed, and the aircraft came to rest on its belly in a nearby meadow.
There were 4 persons on board (the pilot and three passengers), and there were no fatalities, though the aircraft sustained heavy damage.
The investigation
The investigation focused on the mechanical condition of the Lycoming O-360 A3A engine, which had accumulated 4,731 total hours, including 1,356 hours since its last overhaul. Investigators examined the engine components and the magneto systems to determine why the power loss occurred during the climb.
Findings
The investigation established several critical mechanical failures and maintenance deficiencies:
- Significant wear was found on the intake cams and associated tappets for cylinders 1 and 2, which reduced the volume of the air-fuel mixture drawn into the cylinders during each cycle.
- The engine was operating with an excessively lean fuel mixture.
- The carburetor air-mixture valve was incorrectly positioned on the hot air intake.
- The magneto timing was incorrect.
- The right magneto was non-functional during bench testing.
- A recent failure of the teeth on the right magneto drive gear had caused the engine to operate almost exclusively on the left magneto.
Ultimately, the primary cause of the engine failure was identified as insufficient maintenance.