Manchester

During an instrument approach at night in a twin-engine turboprop airplane, the pilot reported an engine failure, but did not specify which engine. About 9 seconds later, the airplane impacted terrain about ¼-mile short of the runway and a postcrash fire consumed a majority of the wreckage. During that last 9-second period of the flight, the airplane’s groundspeed slowed from 99 kts to 88 kts, as it descended about 400 ft in a slight left turn to impact (the airplane’s minimum controllable airspeed was 92 kts). The slowing left turn, in conjunction with left wing low impact signatures observed at the accident site were consistent with a loss of control just prior to impact. Postaccident teardown examination of the left engine revealed that the 1st stage turbine rotor had one blade separated at the midspan. The blade fracture surface had varying levels of oxidation and the investigation could not determine if the 1st stage turbine blade separation occurred during the accident flight or a prior flight. The 2nd stage turbine was operating at temperatures higher than the 1st stage turbine, which was consistent with engine degradation over a period of time. Additionally, the 2nd stage turbine stator assembly was missing vane material from the 6 to 12 o’clock positions, consistent with thermal damage. All of these findings would have resulted in reduced performance of the left engine, but not a total loss of left engine power. The teardown examination of the right engine did not reveal evidence of any preimpact anomalies that would have precluded normal operation. Examination of both propellers revealed that all blade angles were mid-range and exhibited evidence of little to no powered rotation. Neither propeller was in a feathered position, as instructed by the pilot operating handbook for an engine failure. If the pilot had perceived that the left engine had failed, and had he secured the engine and feathered its propeller (both being accomplished by pulling the red Engine Stop and Feather Control handle) and increased power on the right engine, the airplane’s performance should have been sufficient for the pilot to complete the landing on the runway.

The airplane was in cruise flight at FL280 when the instrument-rated pilot failed to contact air traffic control (ATC) following a frequency change assignment. After about 25 minutes, and when 30 miles east of the destination airport, the pilot contacted ATC on a frequency other than the one that was assigned. He requested the instrument landing system (ILS) approach at his intended destination, and the controller instructed the pilot to descend to 8,000 ft and to expect vectors for the ILS approach at the destination airport. The controller asked the pilot if everything was “okay,” to which the pilot replied, “yes sir, everything is fine.” The controller then observed the airplane initiate a descent. About 2 minutes later, the controller asked the pilot where he was headed, and the pilot provided a garbled response. The controller instructed the pilot to stop his descent at 10,000 ft, followed by an instruction to stop the descent at any altitude. The pilot did not respond, and additional attempts to contact the pilot were unsuccessful. The airplane impacted terrain in a heavily wooded area 17 miles from the destination airport. Rhe aircraft disintegrated on impact and both occupants were fatally injured.