Incident
During a takeoff from an offshore platform, the engine of a turbine-powered helicopter lost power following a normal power check. The airline transport rated helicopter pilot, with 14,490 flight hours, recognized that a safe return to the platform was not possible. The pilot turned into the wind, entered autorotation, and deployed the skid-mounted emergency floats. Upon contact with high seas, the helicopter filled with water, inverted, and partially submerged.
Investigation
No mechanical anomalies were found during the examination of the engine. A fuel sample taken from the airframe fuel filter canister contained a yellowish-tan contaminant that had separated from the fuel. A similar yellowish-tan shiny substance was discovered on the paper folds of the airframe fuel filter. The fuel cells were drained and the boost pumps removed. Contamination was found on the exterior surfaces of the boost pump assemblies and on the bottom of the main fuel cell. Both the left and right in-line fuel filters, located between the front and rear fuel tanks, also exhibited contamination.
Further examination revealed that the engine fuel nozzle screen was blocked and collapsed due to a contaminant. One of the fuel facilities where the helicopter had recently refueled provided samples that tested positive for bacterial and fungal growth.
Findings
The investigation determined that the engine fuel nozzle screen was blocked and collapsed because of a contaminant. The contamination was traced to bacterial and fungal growth in fuel from a facility used for refueling.