Accident
While turning from downwind to base leg, the aircraft was observed descending rapidly in a steep bank. Witnesses reported smoke trailing from the aircraft. The aircraft subsequently crashed in an industrial area. All six occupants were killed.
Examination
An examination of the right engine revealed that the exhaust-to-turbo adapter, part number 641829, had fractured and separated. The fracture was a result of thermal fatigue and had propagated across more than 95% of the area before final separation occurred. Examination of the cowling and both engines showed no streaking heat or smoke patterns; therefore, the reported smoke was attributed to exhaust gas. While there was a loss of power in the right engine, no other aircraft malfunctions were found that would have caused loss of control.
Official Probable Cause
The official probable cause was:
- Occurrence #1: loss of engine power (partial) – mechanical failure/malfunction, phase of operation: approach – VFR pattern – base turn. Finding: (c) exhaust system, manifold/pipe – fatigue.
- Occurrence #2: forced landing, phase of operation: maneuvering – turn to landing area (emergency).
- Occurrence #3: in-flight collision with terrain/water, phase of operation: maneuvering – turn to landing area (emergency). Finding: (c) aircraft handling – inadequate – pilot in command.