Accident Sequence
Approximately 11 minutes after takeoff on a night instrument flight rules flight plan, the pilot of the twin-engine airplane radioed air traffic control (ATC) that he was climbing through 7,800 feet. Shortly thereafter, ATC received a "mayday" transmission followed by "lost an engine." Subsequently, radio communications and radar contact with the airplane were lost.
Witnesses reported observing the airplane in an unusually steep descent prior to impacting terrain. One witness said they heard a high-pitched noise emanating from the airplane as it descended toward the ground.
Wreckage and Conditions
The wreckage came to rest in an open field adjacent to a highway. The main wreckage was contained within a large impact crater approximately 15 feet in diameter and 6 feet deep. Dark night conditions with low ceilings prevailed at the time of the accident.
Engine Examination
Post-accident teardown and examination of both engines revealed no evidence of excessive wear or operational failure of internal engine components. However, extensive damage was noted to the right turbocharger assembly. Disassembly of that component revealed damage to the compressor wheel and compressor housing shroud. Circumferential scuffing and pockmarks were observed on the inner compressor housing, while impact-type damage and smearing were found on the individual compressor blades. Scuffing-type damage was also noted on the turbine wheel and corresponding turbine housing.
Additional damage affected the turbine/compressor input shaft and its associated journals and bearings. Foreign material was discovered in the compressor housing and turbocharger after cooler, consisting of aluminum fragments, a rivet head, a piece of brass, paint chips, rubber, gasket material, and dirt. The manufacturer of the turbo assembly examined the unit and reported that the damage was consistent with foreign object damage (FOD) and lubricant starvation. The exact sequence of events leading to the failure of the turbocharger was not determined.