Casualties unknown

Hard Landing and Rollover After Power Train Failure During Low-Altitude Search (N8684F)

Coalville, UT, US

On April 27, 1982, a Hughes 369D (500D) (registration N8684F) operated by Rocky Mountain Helicopters Inc was involved in an aviation accident near Coalville, UT. Investigators recorded the probable cause as: Power train failure. This summary draws on records from the U.S. National Transportation Safety Board (NTSB) historical archive; 6 related events involving the same aircraft type or operator are linked below.

Sourcesthe U.S. National Transportation Safety Board (NTSB) historical archivePrimary reportUpdated 2026-07-04Data APIEditorial standards
Aircraft registered N8684F
Aircraft registered N8684F. Photo: Acroterion / CC BY-SA 4.0, via Wikimedia Commons

A helicopter searching for lost mining equipment under VMC with a VFR flight plan experienced a power train failure while flying low and slow. The pilot avoided trees but made a hard landing on a steep slope, causing the helicopter to roll over.

Accident Overview

A helicopter was engaged in a low-altitude, low-speed search for lost mining equipment under visual meteorological conditions (VMC). A VFR flight plan had been filed for the mission.

Power Train Failure and Emergency Descent

During the search, the power train failed. The pilot, who was looking out of the cockpit, heard the engine-out audio alert in his headset. He initiated a descending maneuver, successfully avoiding trees in the area.

Hard Landing and Rollover

The helicopter made a hard landing on a steep slope. The impact caused the aircraft to roll over. The helicopter came to rest after the rollover.

Outcome

The helicopter came to rest on its side on the steep slope.

Probable Cause

The probable cause, as stated in the investigation source, is a power train failure.

Frequently asked questions

What happened in the 27 Apr 1982 Hughes 369D (500D) accident near Coalville, UT?

A helicopter searching for lost mining equipment under VMC with a VFR flight plan experienced a power train failure while flying low and slow. The pilot avoided trees but made a hard landing on a steep slope, causing the helicopter to roll over.

What aircraft was involved and where did it happen?

The accident on 27 Apr 1982 involved a Hughes 369D (500D), registration N8684F, operated by Rocky Mountain Helicopters Inc, at Coalville, UT.

What was the probable cause of the accident?

Power train failure

Investigation report by the U.S. National Transportation Safety Board (NTSB) historical archive. Original record: https://carol.ntsb.gov/event/20020917X01957. This page is a structured re-presentation; facts and quotes are in the National Transportation Safety Board (NTSB), United States.