Primary finding
Probable cause
The loss of engine power due to the failure of the reduction gear assembly due to fatigue. A factor was the lack of suitable terrain for the forced landing.
Investigator assessment
Analysis narrative
An agricultural airplane with a full load of pesticides was en route to a field to be sprayed when the engine oil pressure dropped and the engine chip detector illuminated. Within seconds, the engine lost power and the pilot elected to execute a forced landing to a cultivated field. During the landing flare, the airplane struck a levee resulting in structural damage to the airframe and engine firewall. Examination of the engine revealed that the power loss was the result of first stage planetary sungear failure due to fatigue.
Source record
Factual narrative
On May 31, 1993, at approximately 1530 central daylight time, an Ayres Corporation SR2-T34 airplane, N6051F, was substantially damaged during a forced landing following a loss of engine power while in cruise flight near Harrisburg, Arkansas. The commercial pilot, sole occupant of the airplane, was not injured. Visual meteorological conditions prevailed for the aerial application flight. According to the operator, the airplane departed the May private airstrip near Harrisburg, with a full load of pesticides. While en route to the field to be sprayed, the engine oil pressure dropped and the engine chip detector illuminated. Within a few seconds, the engine lost power and the pilot performed a forced landing to a field. During the landing flare, the airplane struck a levee resulting in structural damage to the airframe and engine firewall. The engine was preserved and transported to an approved repair station for further inspection and examination. Inspection of the magnetic plug and the screen confirmed that ferrous deposits were present. A complete engine teardown was accomplished. According to the engine manufacturer's representative, "the failure of the engine appeared to originate in the first stage planetary system." A detailded examination of the first stage sungear revealed "some areas of fatigue along the axis of the splines, which resulted in the jamming of the first stage sun gear." The wreckage was verbally released to the owner at the accident site. -