Accident Details
A Beech 65 aircraft collided with trees in mountainous terrain after an inflight loss of control. A witness observed the airplane initiate a right turn, then roll to the right until inverted and enter a spin. The aircraft was in a steep nose-down attitude when it began to pull out. A ground witness heard the engines, initially mistaking the sound for an approaching motorcycle.
The pilot had initially flown the aircraft 45 days before the accident, logging 3.5 hours of dual instruction. No record of additional flight training was found in the pilot's logbook after that date. The pilot satisfactorily completed a check flight in a Cessna 150 four days before the accident.
Investigation Findings
Examination of the wreckage revealed that the right engine had a broken exhaust valve, while the left propeller was feathered. No preexisting mechanical malfunctions or failures were found with the left engine. The aircraft was destroyed in the accident.
Probable Cause
The official probable cause of the accident was improper emergency procedures by the pilot, who inadvertently shut down the left engine after encountering a partial loss of power in the right engine. Factors related to the accident were: improper installation of the right engine's #6 exhaust valve seat by other maintenance personnel, fatigue failure of the #6 exhaust valve, and the pilot's lack of familiarity with the aircraft.