Casualties unknown

2002-01-03: Hughes 369D (N8393F) — Butte, MT

Butte, MT, US

On January 3, 2002, a Hughes 369D (registration N8393F) was involved in an aviation accident near Butte, MT. Investigators recorded the probable cause as: A loss of engine power during flight that necessitated an emergency autorotation landing, for which no mechanical failure was identified in the engine. This summary draws on records from the U.S. National Transportation Safety Board (NTSB) historical archive.

Sourcesthe U.S. National Transportation Safety Board (NTSB) historical archivePrimary reportUpdated 1781061362Data APIEditorial standards

A helicopter lost engine power while flying at low altitude, forcing the pilot to execute an autorotation between highway lanes. The tailboom separated during the landing, though no mechanical failure was found in the engine.

What happened

The pilot was operating a helicopter on a flight when the engine experienced a sudden loss of power. At the time of the incident, the aircraft was flying at an altitude between 600 and 800 feet above ground level. Unable to maintain engine thrust, the pilot initiated an autorotation maneuver to control the descent.

The pilot guided the helicopter toward a median strip located between lanes of a highway. During the landing phase of this emergency procedure, the tailboom was severed from the main fuselage. The aircraft came to rest on the median following the separation.

The investigation

Following the accident, investigators conducted a thorough post-accident inspection of the helicopter's engine. To further assess the condition of the powerplant, a subsequent test cell run was performed on the engine.

The examination and testing did not reveal any evidence of mechanical failure or malfunction within the engine components. The results indicated that the engine itself was functioning mechanically correctly at the time of the inspection, despite the in-flight power loss experienced by the pilot.

Probable cause

A loss of engine power during flight that necessitated an emergency autorotation landing, for which no mechanical failure was identified in the engine.

Investigation report by the U.S. National Transportation Safety Board (NTSB) historical archive. Original record: https://carol.ntsb.gov/event/20020116X00081. This page is a structured re-presentation; facts and quotes are in the National Transportation Safety Board (NTSB), United States.