On September 16, 1988, a Hughes 369HS (registration N9110F) operated by Inter Mountain Helicopters was involved in an aviation accident near Columbia, CA. Investigators recorded the probable cause as: Improper installation of the number six and seven oil screens restricted the flow of oil, leading to lack of lubrication and excessive temperatures, causing engine power loss. This summary draws on records from the U.S. National Transportation Safety Board (NTSB) historical archive.
During an external load operation, the helicopter experienced high torque and oil chip indication, followed by engine power loss. The pilot autorotated, but the helicopter collided with sloping terrain and rolled over. Investigation found improperly installed oil screens restricting oil flow.
Incident Overview
During an external load operation, the helicopter's engine displayed an indication of high torque, and the oil chip light illuminated. Subsequently, the engine lost power, prompting the pilot to initiate an autorotation. The helicopter collided with sloping terrain and rolled over.
Engine Inspection Findings
Inspection of the engine revealed that the number six and seven oil screens were improperly installed, which restricted the flow of oil. The entire engine exhibited signs of lack of lubrication and excessive temperatures.
Probable Cause
The improper installation of the number six and seven oil screens, restricting oil flow, leading to engine power loss.