Accident Sequence
During a power-on stall sequence, the aircraft's engine experienced a significant partial power loss, and the engine oil pressure subsequently dropped to zero. The pilot assessed the situation and determined that there was no suitable landing area directly below the location where the power loss occurred. Consequently, the pilot turned the aircraft to the south and attempted to land on what appeared to be the only available reasonably safe terrain.
Based on a quick evaluation of the landing site, the pilot decided to keep the landing gear fully retracted. The initial touchdown was uneventful, but shortly thereafter, the aircraft contacted rough and uneven terrain. This contact resulted in substantial damage to the airframe.
Post-Accident Engine Inspection
A post-accident inspection of the engine revealed a crack in the crankcase mating flange at two different places. Additionally, the number three cylinder push rod and push rod tube were bent, consistent with compression of the pushrod from its ends. The heads of six of the eight cam followers had fractured. Behind all but two of the follower heads, the crankcase surface was dented and gouged. Behind two of the heads, there were small chunks of fractured steel embedded or crushed into the metal of the case. Removal of the oil pan revealed about a dozen metal pieces that were clearly identifiable as sections of the cam follower heads. Further inspection of the engine and its cylinders could not determine the initiating event that led to the fracturing of the cam followers.
Summary
The event involved a forced landing following engine power loss and oil pressure failure during a stall sequence. The aircraft sustained substantial damage upon contacting rough terrain with the gear retracted. The engine examination found multiple internal failures, but the root cause of the cam follower fracturing could not be identified.