What happened
Witnesses observed a Mitsubishi aircraft perform a rolling takeoff, becoming airborne approximately 1,300 feet down the 6,600-foot runway. The aircraft entered a nose-high climb at an approximate 40-degree angle, reaching about 1,000 feet before entering a steep left-hand banking turn. During this maneuver, the nose dropped and the aircraft rotated approximately four times before colliding with flat terrain adjacent to the departure end of the runway threshold. The accident resulted in 1 fatality.
Performance calculations indicated that while the aircraft was capable of lifting off at the observed location and climbing to 1,000 feet, achieving such performance would have required rotating at approximately 84 KCAS. This speed is below Vmc (100 KCAS) and close to the power-off stall speed of 86 KCAS with 5 degrees of flaps.
The investigation
An examination of the airframe revealed no evidence of flight control malfunction. However, an engine teardown of the left engine identified that the gearbox section experienced a high cycle fatigue failure of the high-speed pinion journal bearing oil supply tube. This led to the subsequent degradation of the high-speed pinion journal bearings, resulting in partial power loss to the left engine.
Investigation into the pilot's experience noted that while the pilot had accumulated approximately 551 hours in Mitsubishi aircraft, he had not flown this specific make and model for 14 years. Furthermore, logbook entries showed the pilot had only accumulated a few hours of total flight time across all aircraft during the two years preceding the accident. Personnel who had flown with the pilot described him as "proficiency lacking."
On-site documentation of the cockpit controls found the left side condition lever in the takeoff/land position, and the power lever was positioned halfway between takeoff and flight idle.