On February 10, 1983, a Bell 47G-5 (registration N1375X) was involved in an aviation accident near Irvine, CA. Investigators recorded the probable cause as: The pilot's failure to maintain adequate airspeed during takeoff, which resulted in a stall and subsequent loss of control. Contributing to the accident was the improper seating of piston rings on three cylinders, which caused oil leakage and carbon fouling. This summary draws on records from the U.S. National Transportation Safety Board (NTSB) historical archive.
A helicopter experienced engine power loss shortly after takeoff, resulting in a hard landing in a field near the airport. An investigation revealed mechanical issues with the engine cylinders.
What happened
The helicopter sustained significant damage after landing hard in a field located off the airport. The incident occurred during the initial phase of flight. After lifting off, the aircraft traveled approximately 50 feet at an altitude of 15 feet above ground level when it experienced a sudden loss of engine power.
The investigation
A thorough examination of the aircraft was conducted to determine the cause of the failure. An engine teardown revealed that the piston rings on three cylinders had not seated properly. This mechanical issue caused oil to leak into the combustion chambers, leading to carbon fouling of the spark plugs in those cylinders.
Findings
The primary factor contributing to the accident was the engine power loss resulting from improper seating of piston rings. The leakage of oil into the combustion chambers prevented proper engine function, leading to the immediate loss of thrust during takeoff. No other mechanical failures were identified during the investigation.
Probable cause
The pilot's failure to maintain adequate airspeed during takeoff, which resulted in a stall and subsequent loss of control. Contributing to the accident was the improper seating of piston rings on three cylinders, which caused oil leakage and carbon fouling.