On October 22, 1989, a Hughes 369HS (registration N3961H) was involved in an aviation accident near Ogilvie, MN. Investigators recorded the probable cause as: LOSS OF ENGINE POWER FOR AN UNDETERMINED REASON. FACTORS RELATED TO THE ACCIDENT WERE: THE UNSUITABLE TERRAIN CONDITIONS IN THE EMERGENCY LANDING AREA. This summary draws on records from the U.S. National Transportation Safety Board (NTSB) historical archive.
After dropping a sling load during a fire control operation, the pilot experienced engine RPM loss and conducted an emergency autorotation. The helicopter touched down in a swampy area, rolled over, and sustained damage. No mechanical failure or fuel shortage was found.
Incident Overview
During a helicopter fire control operation, the pilot reported that after releasing a sling load, the engine RPM began to drop. Subsequently, the engine out light illuminated, accompanied by a low RPM warning audio alert. The pilot initiated an emergency autorotation.
Landing and Damage
The autorotation was performed in a burned-out swampy area. Upon touchdown, the helicopter rolled over and sustained damage.
Investigation Findings
Post-accident examination found no pre-accident part failure or malfunction of the engine or any systems. Additionally, there was no evidence of a fuel supply shortage.