Casualties unknown

Helicopter Rolls Over After Autorotation Landing (N9350F)

Big Bear, CA, US

On June 25, 1988, a Hughes 269B (registration N9350F) operated by Western Aviation was involved in an aviation accident near Big Bear, CA. Investigators recorded the probable cause as: The pilot's failure to maintain rotor RPM during cruise flight, which resulted in an autorotation and subsequent rollover upon landing on soft ground. This summary draws on records from the U.S. National Transportation Safety Board (NTSB) historical archive; 1 related events involving the same aircraft type or operator are linked below.

Sourcesthe U.S. National Transportation Safety Board (NTSB) historical archivePrimary reportUpdated 2026-06-10Data APIEditorial standards

A private pilot experienced a loss of engine and rotor RPM while cruising, performed an autorotative landing, and the aircraft rolled over upon touchdown on soft ground.

What happened

The accident occurred while the helicopter was in cruise flight. The pilot reported that he perceived a simultaneous loss of engine power and rotor revolutions per minute (RPM). In response to this mechanical anomaly, the pilot initiated an autorotation to maintain rotor speed and control the descent.

During the autorotative descent, the pilot successfully regained the necessary RPM to sustain controlled flight. Rather than attempting an immediate emergency landing elsewhere, the pilot elected to continue the descent toward a planned landing site. Upon touchdown, the aircraft encountered soft ground conditions which contributed to the loss of directional control. The helicopter subsequently rolled over onto its side.

The investigation

Examination of the circumstances revealed that the pilot had been issued a rotorcraft-helicopter private pilot certificate only three days prior to the accident. This indicates the pilot was in the early stages of certification at the time of the event.

Probable cause

The pilot's failure to maintain rotor RPM during cruise flight, which resulted in an autorotation and subsequent rollover upon landing on soft ground.

Investigation report by the U.S. National Transportation Safety Board (NTSB) historical archive. Original record: https://carol.ntsb.gov/event/20001213X26004. This page is a structured re-presentation; facts and quotes are in the National Transportation Safety Board (NTSB), United States.