On February 2, 1987, a Bell 47G4A (registration N28938) was involved in an aviation accident near Stockton, CA. This summary draws on records from the U.S. National Transportation Safety Board (NTSB) historical archive.
Shortly after takeoff, an aircraft transporting agricultural equipment experienced an engine power loss. Examination revealed a fatigue fracture in the fuel disconnect fitting's retaining ring, which could have disrupted fuel supply.
Incident
Shortly after takeoff, while transporting agricultural equipment, the aircraft's engine experienced a loss of power. The event prompted an investigation into the cause of the power loss.
Examination Findings
A fractographic examination of the failed fuel disconnect fitting was conducted by Anamet Laboratories. The analysis concluded that approximately 70% of the retaining ring on the fuel disconnect fitting had fractured due to metal fatigue. The fatigue crack was determined to have been present prior to the crash. However, investigators could not determine whether the fracture may have caused partial closing of the disconnect valve within the fitting. Such partial closing could cut off the fuel supply during operation.
Conclusion
The investigation identified a pre-existing fatigue crack in the fuel disconnect fitting's retaining ring, but whether this fracture directly led to the power loss could not be definitively established. The potential for the fracture to cause partial valve closure and subsequent fuel starvation remains a plausible scenario.