Synopsis
A Mitsubishi MU-2B-25 experienced a control problem and left engine shutdown during an approach, leading to a loss of control. The pilot reported the issues to air traffic control, and the aircraft subsequently descended out of view. Postaccident examination revealed the landing gear was extended, flaps were at 20 degrees, and the left engine propeller blades were feathered. The left engine fuel shutoff valve was found closed, consistent with an inoperative engine. The aircraft was not configured in accordance with the airplane flight manual engine shutdown and single-engine landing procedures, which call for a clean configuration with flaps at 5 degrees at the beginning of final approach and landing gear retracted until landing is assured.
Flight History
Radar and air traffic control communications indicated that the flight was normal from takeoff through the beginning of the approach, until the aircraft overshot the extended centerline of the landing runway by about 0.2 nautical mile to the east and left of course. It briefly tracked back toward the centerline, then entered a 360-degree left turn east of the centerline at an altitude far below what would be expected for a nominal flightpath and intentional maneuvering, given the aircraft's distance of about 5 miles from the airport. As the aircraft sustained the left turn away from the airport, the controller queried the pilot, who stated he had a "control problem" and then said he had a "left engine shutdown." This was the last communication. Witnesses saw the aircraft spiral toward the ground and disappear from view.
Wreckage Examination
Examination of the wreckage showed the landing gear extended, flaps extended 20 degrees, and the left engine propeller blades feathered. The left engine fuel shutoff valve was in the closed position, consistent with an inoperative engine. Thermal damage to cockpit instrumentation precluded determining the preimpact position of fuel control and engine switches. The aircraft was not equipped with any crash-resistant recorder, and no flight data or cockpit voice recordings were available.
Pilot Background
The pilot was properly certificated and qualified in accordance with applicable federal regulations, including Special Federal Aviation Regulation (SFAR) No. 108, which is required for MU-2B pilots. He had recently completed SFAR No. 108 training in Kansas and was returning to Tulsa. At the time of the accident, he had about 12 hours total time in the airplane make and model, and this flight was his first solo operation of the aircraft. No evidence indicated any preexisting medical or behavioral conditions that might have adversely affected his performance.
Investigation Findings
The investigation found that the aircraft was properly certified, equipped, and maintained in accordance with federal regulations. Recovered components showed no evidence of preimpact structural, engine, or system failures. Aircraft performance calculations indicated the airplane should have been flyable in a one-engine-inoperative condition, and the day visual meteorological conditions do not support loss of control due to spatial disorientation. The available evidence indicates that the pilot did not appropriately manage a one-engine-inoperative condition, leading to a loss of control from which he did not recover. The reasons for the left engine shutdown and the pilot's recognition and response could not be determined due to the lack of a crash-resistant recorder and the inability to examine certain cockpit controls. Recorded data would have aided the investigation.