What happened
The pilot was operating an aircraft during an aerial patrol flight when he reported a sudden loss of engine power. With no airport immediately available, the pilot initiated an emergency landing procedure, aiming for a nearby field. The terrain conditions were soft, which contributed to the severity of the impact upon touchdown.
During the landing roll, the nose gear sheared off due to the stress on the soft ground. Consequently, the aircraft nosed over, coming to rest on its upper fuselage and wings. The force of the nosing-over caused significant structural damage to the forward section of the airframe.
The investigation
Following the accident, investigators conducted a thorough examination of the aircraft's engine components to determine the root cause of the power loss. The inspection focused heavily on the exhaust system and valve mechanisms, as these are critical for proper engine function.
The technical analysis revealed that the number one exhaust valve had failed completely. This mechanical failure prevented the engine from operating correctly, leading directly to the total loss of power during the flight phase.