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Engine Power Loss During Air Taxi Cargo Flight Leads to Autorotation and Tail Boom Separation (N5108E)

Vallejo, CA, US

On March 31, 1989, a Hughes 369D (registration N5108E) operated by Helinet, Inc. was involved in an aviation accident near Vallejo, CA. No fatalities were reported. 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.

Sourcesthe U.S. National Transportation Safety Board (NTSB) historical archivePrimary reportUpdated 2026-07-04Data APIEditorial standards

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.
Engine failureStructural failure

Related events

Same operator

Frequently asked questions

What happened in the 31 Mar 1989 Hughes 369D accident near Vallejo, CA?

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.

Were there any fatalities in the 31 Mar 1989 Hughes 369D accident?

No fatalities were recorded in this accident.

What aircraft was involved and where did it happen?

The accident on 31 Mar 1989 involved a Hughes 369D, registration N5108E, operated by Helinet, Inc., at Vallejo, CA.

What was the probable cause of the accident?

Fatigue failure of the PC tube assembly at the scroll fitting ferrule, resulting in an immediate loss of engine power.

More accident analyses

Investigation report by the U.S. National Transportation Safety Board (NTSB) historical archive. Original record: https://carol.ntsb.gov/event/20001213X27929. This page is a structured re-presentation; facts and quotes are in the National Transportation Safety Board (NTSB), United States.