Incident Overview
An aerial application airplane experienced a total loss of engine power during a spraying operation, resulting in a forced landing and subsequent nose-over. The pilot reported that the backfire plate began opening and closing while the aircraft was spraying a field. After reducing power and pulling out of the field, the engine operated normally for about 15 seconds before becoming rough and losing all power.
Forced Landing
The pilot maneuvered the airplane into the wind to execute a forced landing. During the landing roll on rough and uneven terrain, the tires sank into the soft ground, causing the airplane to nosed over and come to rest inverted.
Engine Examination
An examination of the wreckage and engine did not determine a reason for the loss of engine power. The cause remains unknown.