On November 25, 1986, a Hughes 369D (registration N8670F) was involved in an aviation accident near Newark, DE. Investigators recorded the probable cause as: The pilot's failure to ensure adequate fuel supply, associated with a bent and binding fuel float arm. This summary draws on records from the U.S. National Transportation Safety Board (NTSB) historical archive.
A helicopter experienced engine power loss due to fuel exhaustion during a maintenance check flight. The pilot executed an autorotative landing, resulting in extensive damage to the main rotor blades and tail boom.
What happened
The aircraft was operating on a maintenance check flight when the engine lost power due to fuel exhaustion as the pilot was returning to land. During the subsequent autorotative landing, the main rotor blades and tail boom sustained extensive damage. The pilot reported that the fuel quantity gauge indicated 120 lbs of fuel remained at the moment the engine lost power.
The investigation
An examination of the fuel float arm, part number 369D296303-3, revealed that it was bent and binding on the internal fuel pump housing. This mechanical interference likely prevented accurate fuel quantity measurement or flow, contributing to the fuel exhaustion.
Findings
The investigation identified a bent fuel float arm as a critical factor. The binding of this component against the internal fuel pump housing compromised the system's ability to function correctly during the flight.
Probable cause
The pilot's failure to ensure adequate fuel supply, associated with a bent and binding fuel float arm.