On July 24, 1991, a Bell 47D-1 (registration N3575) operated by Superior Heli. OF Louisiana was involved in an aviation accident near Provencal, LA. Investigators recorded the probable cause as: Fuel exhaustion resulting from fuel draining out of the fuel cell sump drain valve due to failure or premature deterioration. This summary draws on records from the U.S. National Transportation Safety Board (NTSB) historical archive.
A commercial helicopter experienced an engine failure 15 minutes into an aerial burning mission due to fuel exhaustion, caused by fuel leaking from the sump drain valve.
Incident Overview
A commercial helicopter engaged in aerial ignition operations experienced a loss of engine power approximately 15 minutes after departure. The aircraft was being maneuvered to ignite approximately 15 acres of timber. Prior to departure, the pilot measured the fuel level at just over 11 gallons. Given a fuel consumption rate of 13 to 15 gallons per hour, the helicopter had an estimated 40 to 50 minutes of fuel available for the intended 20- to 30-minute mission.
Engine Failure and Fuel Exhaustion
The engine ceased operation 15 minutes into the flight due to fuel exhaustion. Investigation revealed that fuel had drained from the helicopter's fuel cell sump drain valve as a result of failure or premature deterioration of the valve. The loss of fuel through the drain valve led to the fuel exhaustion that caused the engine to stop.
Operational Context
The helicopter was operating in a commercial capacity for aerial burning, a technique used in land management to reduce wildfire fuel loads or prepare sites for reforestation. The pilot was conducting the ignition using equipment attached to the helicopter. No further details regarding the location, aircraft registration, or post-incident outcomes were provided in the source materials.
Probable cause
Fuel exhaustion resulting from fuel draining out of the fuel cell sump drain valve due to failure or premature deterioration.