On March 31, 1989, a Hughes 369D (registration N5108E) operated by Helinet, Inc. was involved in an aviation accident near Vallejo, CA. Investigators recorded the probable cause as: Fatigue failure of the PC tube assembly at the scroll fitting ferrule, resulting in an immediate loss of engine power. This summary draws on records from the U.S. National Transportation Safety Board (NTSB) historical archive; 1 related events involving the same aircraft type or operator are linked below.
During an air taxi cargo flight, sudden engine power loss forced the pilot to autorotate onto a wet marsh. The main rotors severed the tail boom upon landing. Investigation found fatigue failure of a PC tube assembly.
Accident Summary
During an air taxi cargo flight, the engine suddenly lost power. The pilot performed an autorotation and landed on a wet marsh. As the aircraft came to rest, the main rotor blades severed the tail boom.
Investigation Findings
Examination of the engine revealed that the PC tube assembly, part number 6848471, had failed at the scroll fitting ferrule. The broken line condition produced an immediate loss of engine power. The PC tube had accumulated a total of 11.8 hours of use since being installed or manufactured.
A metallurgical failure analysis determined that the PC tube had failed due to fatigue. No other contributing factors were identified in the source material.
Probable cause
Fatigue failure of the PC tube assembly at the scroll fitting ferrule, resulting in an immediate loss of engine power.