FTW00LA118

The pilot reported that during the aerial application flight, the engine 'lost torque while spraying at ground level.' The pilot diverted to an adjacent open field for the forced landing. During the landing roll, the main landing gear sank in the wet field, and the airplane nosed over to the inverted position. An engine teardown revealed a failure of the spur gear from the torque sensor gear assembly. The Garrett TPE 331 engine had accumulated 8,395 flight hours since the last major overhaul. Total flight time since a hot section and gearbox change was 793 hours.

On April 6, 2000, at 0800 central daylight time, an Ayres S2R-G6 agricultural airplane, N3004V, sustained substantial damage during a forced landing following a loss of engine power near Oak Grove, Louisiana. The airplane was owned and operated by Carroll Flying Service, Inc., of Pioneer, Louisiana, under 14 Code of Federal Regulations Part 137. The commercial pilot, sole occupant, was not injured. Visual meteorological conditions prevailed for the local aerial application flight, and a flight plan was not filed. The flight departed the Bayou Meadow Farm Airport near Oak Grove, Louisiana, at 0745.

The pilot reported that the engine "lost torque while spraying at ground level." The pilot diverted to an adjacent open field for the forced landing. During the landing roll, the main landing gear sank in the muddy field, and the airplane nosed over to the inverted position.

The FAA inspector responding to the site found structural damage to the outboard right wing leading edge, the vertical stabilizer, and the rudder. The propeller blades were bent, and the cockpit canopy was crushed.

The FAA inspector reviewed the maintenance records. Total time on the aircraft was 3,446 hours. The Garrett TPE 331 engine had accumulated 8,395 flight hours since the last major overhaul. Total flight time since a hot section and gearbox change was 793 hours.

The NTSB did not take possession of the aircraft.

On April 25, 2000, the owner's representative observed the engine teardown at Tulsa, Oklahoma. The examination revealed a failure of the spur gear (part number 896884-1) from the torque sensor gear assembly.