On April 21, 1987, a Bell UH-1B (registration N88987) operated by Pacific Helicopter,inc. was involved in an aviation accident near Bay Minette, AL. Investigators recorded the probable cause as: The shifting of the compressor turbine from its normally installed position, which caused a complete engine failure during flight. This summary draws on records from the U.S. National Transportation Safety Board (NTSB) historical archive.
A helicopter suffered a complete engine failure shortly after attempting a pickup during a logging operation. The pilot executed an autorotative glide, but the aircraft impacted and sank in water. Investigation revealed a shifted compressor turbine caused the power loss.
What happened
During a routine logging operation, the helicopter experienced a sudden and complete engine failure shortly after the crew attempted to pick up a load. In response to the loss of power, the pilot immediately initiated an autorotative glide to maintain control and attempt a safe descent. Despite these efforts, the aircraft was unable to avoid contact with the surface below. The helicopter impacted the water and subsequently sank.
The investigation
A thorough examination of the wreckage was conducted to determine the mechanical cause of the failure. Inspectors discovered that the compressor turbine had shifted from its normally installed position within the engine assembly. This displacement prevented the engine from generating power, leading directly to the in-flight failure. Records indicated that the engine had accumulated approximately 980 hours since its last overhaul.
Findings
The primary factor contributing to the accident was the mechanical failure of the engine due to the shifted compressor turbine. This internal component displacement resulted in a total loss of power during a critical phase of the operation. The pilot's decision to enter an autorotative glide was appropriate given the circumstances, but the structural integrity of the helicopter could not withstand the impact with the water.
Probable cause
The shifting of the compressor turbine from its normally installed position, which caused a complete engine failure during flight.