Factual Narrative
During the initial takeoff climb, the pilot reduced power, and the engine's revolutions per minute (rpm) dropped to zero. However, the pilot reported no corresponding change in engine sound. The pilot then attempted to return to the airport for a precautionary landing. While turning back, the engine began to run rough. The pilot was unable to reach the runway and performed an off-airport emergency landing, during which the aircraft collided with ground obstructions.
Investigation Findings
A post-accident investigation revealed that the engine had experienced an oil starvation failure. The oil pump's drive gear shaft had failed due to torsional overload. Examination of the oil pump's driven gear showed that the required bronze bushings between the driven gear and its shaft were absent. This absence led to the oil starvation that caused the engine failure.
Maintenance History
The engine had been overhauled 162 hours prior to the accident. During that overhaul, the oil pump was sent out for servicing and was returned to the owner as a disassembled unit. The owner/pilot, who was not a certified Airframe and Powerplant (A&P) mechanic, reassembled the oil pump and reinstalled it on the aircraft. A certified A&P mechanic reported signing the logbook to indicate the work was completed, but he did not monitor or inspect the work that had been performed by the owner.