On January 15, 1992, a Hughes 369D (registration N8674F) operated by Sun Dun Inc. OF Washington was involved in an aviation accident near Edison, NJ. Investigators recorded the probable cause as: THE BLOCKAGE OF THE FUEL NOZZLE WHICH RESULTED IN PARTIAL LOSS OF ENGINE POWER. CONTRIBUTING WAS THE PILOT'S FAILURE TO MAINTAIN ROTOR RPM. This summary draws on records from the U.S. National Transportation Safety Board (NTSB) historical archive.
A helicopter experienced a Dutch roll, collided with power lines, and was destroyed by post-crash fire. Examination revealed a separated driveshaft and corroded fuel nozzle.
Accident Sequence
A witness reported observing the helicopter at approximately 800 feet above the ground. Initially, the engine sounded normal. Shortly thereafter, the engine speed increased, and the helicopter began a Dutch roll—a side-to-side banking motion—for two cycles. The helicopter then rolled over one and a half times in a nose-first orientation as it descended behind trees. The aircraft subsequently collided with power lines before impacting the ground in a nose-down attitude. A post-crash fire destroyed the helicopter.
Examination Findings
Post-accident examination of the aircraft confirmed continuity of the transmission gearbox and internal rotational damage to the engine. However, there was no significant rotational damage to the main rotor, tail rotor, or the engine-to-transmission driveshaft (short shaft). The driveshaft had separated from its Bendix couplings and was crushed almost flat. No evidence of rotational damage was observed between the separated halves of the shaft. Metallurgical examination revealed that the fuel nozzle was corroded with ferrous fibers.