Incident Description
The pilot reported that while climbing, a loud bang was heard accompanied by a spray of oil across the front windscreen. Several seconds later, smoke began to develop within the cockpit. The pilot secured the engine and executed an off-airport landing. During the rollout, the aircraft encountered rough, deeply furrowed terrain, causing the landing gear to collapse.
Examination Findings
Post-crash examination of the aircraft's engine revealed that the three-quarter inch hex head plug at the front of the engine, which retains the propeller governor idler gear shaft, had backed out of its threaded insert. The plug was found in the bottom of the engine, and no safety wire was attached to it; additionally, no safety wire was observed on the tie-down point on the engine. The propeller governor idler gear shaft setscrew was loose, and the gear shaft itself was missing. With the hex head plug and propeller governor idler gear shaft released, engine oil under pressure could exit the engine.
Maintenance Background
The engine had been overhauled 248.2 hours prior to the accident and subsequently repaired for a propeller strike. It could not be determined whether any action related to the safety wiring of the hex plug or any adjustment to the setscrew had been conducted at the overhaul or during the propeller strike repair.