Event Description
After takeoff, as the aircraft was over the departure end of the runway, the tower controller observed deep gray colored smoke trailing from the right engine. The controller alerted the pilot, who acknowledged and advised that the flight was returning. Witnesses reported seeing smoke trailing the right engine, followed by the airplane rolling to the left, pitching nose down, impacting trees, and then the ground.
Investigation Findings
Examination of the right engine revealed a fatigue crack in the exhaust pipe aft of the No. 6 cylinder, as well as incomplete fusion of a weld repair. Heat-damaged components from the right engine were replaced, and the engine was started and found to operate normally. Additionally, a foreign object of undetermined origin was present in the intake area of the No. 3 cylinder.
Analysis of the voice tape indicated that both engines and propellers were operating near full rated revolutions per minute (rpm) when the pilot acknowledged the smoke warning. Subsequently, one engine or propeller rpm decreased to approximately 2,160 rpm.
Inspection of the flight controls showed no evidence of preimpact failure or malfunction. The flap positions at the time of impact could not be determined.
Calculations determined that the airplane was approximately 55 pounds over the maximum certificated takeoff weight at takeoff.
Probable Cause
The official probable cause was the pilot's failure to maintain airspeed (Vs) during a single engine approach, resulting in an inadvertent stall. Contributing factors included a fatigue crack in the exhaust pipe of the right engine, the aircraft weight and balance being exceeded, degraded aircraft performance, and the pilot's diverted attention.