1 fatality

1990-02-09: Mitsubishi MU-2 Marquise (N64MD) — Aeromedical Services — Rapid City, United States of America

Rapid City, United States of AmericaTakeoff (climb)

On February 9, 1990, a Mitsubishi MU-2 Marquise (registration N64MD) operated by Aeromedical Services was involved in an aviation accident near Rapid City, United States of America during takeoff. One person was killed. Investigators recorded the probable cause as: Failure of the pilot to maintain adequate airspeed (VMC), which resulted in a loss of aircraft control. A factor related to the accident was: fatigue failure of a coupling shaft in the #1 engine, which resulted in loss of power in that engine. This summary draws on records from the Bureau of Aircraft Accidents Archives (B3A).

Sourcesthe Bureau of Aircraft Accidents Archives (B3A)Primary reportUpdated 1781213196Data APIEditorial standards

Shortly after lift-off, an aircraft entered an unusually steep, nose-high attitude at low airspeed, then stalled and crashed inverted. The investigation revealed a fatigue failure in the left engine coupling shaft, causing the propeller to feather. One pilot was killed, three others injured.

Accident Sequence

Witnesses observed that immediately after lift-off, the aircraft assumed an abnormally steep, nose-high pitch angle while still at low airspeed. One witness, an airline transport pilot, reported that the aircraft climbed to an estimated altitude of 75 to 100 feet, appeared to decelerate, and then entered what the witness described as a VMC roll. The aircraft subsequently impacted the ground in an inverted, nose-down attitude to the left of the runway.

Investigation Findings

Post-accident examination revealed that a coupling shaft, part number 865888-3, had failed in the left engine. The failure resulted in the left propeller feathering. A metallurgical analysis of the coupling shaft indicated the presence of fatigue as the failure mechanism. The investigation did not specify the aircraft type, registration, operator, or other contextual details beyond the immediate circumstances of the flight.

Probable Cause

The official probable cause was determined to be the pilot's failure to maintain adequate airspeed (VMC), which led to a loss of aircraft control. A factor related to the accident was the fatigue failure of a coupling shaft in the No. 1 engine, which caused a loss of power in that engine.