What happened
Following the completion of field spraying operations, a tail-wheel agricultural airplane was departing the area when the engine experienced a partial loss of power. A witness reported hearing the engine pop, similar to the sound of an overly lean mixture, after which the engine appeared to stabilize but failed to maintain full throttle.
While flying at approximately 150 feet above ground level, the aircraft entered a 90-degree turn and subsequently plunged nose-first into a pond. The pilot was not injured in the accident.
The investigation
Investigators examined the aircraft and confirmed that all major components remained intact at the crash site, with control continuity established to the flight controls. An examination of the engine revealed thermal and mechanical damage to the crankshaft, connecting rods, and connecting rod bearings. This damage was consistent with a lack of lubrication. Specifically, the number four connecting rod bolt was found to be completely fractured. While the oil sump contained residual oil and had not been compromised during the impact, investigators were unable to determine the specific cause for the loss of engine oil.