On November 23, 1990, a Bell 47J2A (registration N8514P) operated by Arthur J. Pryor was involved in an aviation accident near Matoaca, VA. Investigators recorded the probable cause as: The pilot's failure to ensure adequate fuel supply and the obstruction of the left fuel tank vent by mud, which led to engine power loss. This summary draws on records from the U.S. National Transportation Safety Board (NTSB) historical archive.
A helicopter experienced complete engine power loss due to a mud-obstructed fuel tank vent, forcing the pilot to execute an autorotation landing in a plowed field where the aircraft sustained substantial damage.
What happened
The pilot reported that while en route, the engine began running rough. Shortly thereafter, the engine lost power completely. The pilot initiated an autorotation and landed the helicopter in a plowed field. Upon landing, the aircraft was substantially damaged.
The investigation
A post-accident examination of the helicopter revealed that the left fuel tank was one-third full, while the right tank was empty. Investigators found that the vent for the left fuel tank was obstructed with mud.
Findings
The obstruction of the left fuel tank vent prevented proper fuel flow, leading to engine failure. The pilot's decision to perform an autorotation landing resulted in a controlled descent but caused substantial damage to the helicopter upon impact with the ground.
Probable cause
The pilot's failure to ensure adequate fuel supply and the obstruction of the left fuel tank vent by mud, which led to engine power loss.