On March 17, 1995, a Bell 47 (registration N6569H) was involved in an aviation accident near Harmon Field. Investigators recorded the probable cause as: an engine failure due to oil exhaustion from a missing oil pressure relief valve as the result of an improper maintenance inspection. This summary draws on records from the U.S. National Transportation Safety Board (NTSB) historical archive.
A pilot experienced a loss of engine power at 400 feet AGL while approaching a landing area. The helicopter autorotated into dense jungle. Investigation found the oil pressure relief valve missing after a 100-hour inspection the previous day.
Incident Overview
A pilot was proceeding to a landing area at an altitude of 400 feet above ground level when the engine lost power. The pilot performed an autorotation, which ended with the helicopter impacting dense jungle terrain.
Investigation Findings
Examination of the engine after the accident revealed that the oil pressure relief valve was missing. The flight was the first since a 100-hour inspection completed the day before the incident. The inspection of the safety wire securing the valve is not a preflight item for the pilot, nor is it required to be inspected prior to flight.
What happened in the 17 Mar 1995 Bell 47 accident near Harmon Field?
A pilot experienced a loss of engine power at 400 feet AGL while approaching a landing area. The helicopter autorotated into dense jungle. Investigation found the oil pressure relief valve missing after a 100-hour inspection the previous day.
What aircraft was involved and where did it happen?
The accident on 17 Mar 1995 involved a Bell 47, registration N6569H, at Harmon Field.
What was the probable cause of the accident?
an engine failure due to oil exhaustion from a missing oil pressure relief valve as the result of an improper maintenance inspection.
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