On May 28, 1987, a Hughes 369HS (registration N9180F) operated by Helicopter Minit-men,inc. was involved in an aviation accident near Hawesville, KY. Investigators recorded the probable cause as: The B-nut on the flexible fuel line to the engine-driven fuel pump was not properly secured when the engine was last installed. This summary draws on records from the U.S. National Transportation Safety Board (NTSB) historical archive.
A helicopter lost engine power at 45 feet altitude while spraying weeds. The autorotation attempt ended with impact on its left side. Investigation found a loose fuel line B-nut, indicating improper installation of the engine seven hours prior.
Incident Description
During a weed control spraying operation, a helicopter experienced a power failure while at an altitude of 45 feet above ground level. The pilot attempted an autorotation, but the helicopter impacted the ground on its left side.
Investigation
The subsequent investigation into the accident revealed that the flexible fuel line to the engine-driven fuel pump was loose at the B-nut connection. The engine assembly had been installed approximately seven hours prior to the accident. No other system failures were identified. It was apparent that the B-nut was not properly secured when the engine was last installed.
Findings
A detailed examination of the fuel system confirmed that the B-nut on the flexible fuel line was not adequately tightened. The engine installation, which took place about seven hours before the accident, did not ensure that this critical connection was secured. With no other mechanical issues found, the investigation concluded that the loose connection was the only anomaly.
Probable cause
The B-nut on the flexible fuel line to the engine-driven fuel pump was not properly secured when the engine was last installed.