NTSB Identification: MIA03TA036.
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Accident occurred Thursday, January 02, 2003 in New Port Richey, FL
Probable Cause Approval Date: 04/28/2004
Aircraft: Hughes OH-6, registration: N317LC
Injuries: 2 Uninjured.
NTSB investigators may not have traveled in support of this investigation and used data provided by various sources to prepare this public aircraft accident report.
The pilot stated that after takeoff while in a left turn climbing through 600 feet at 60 knots indicated airspeed, he heard a loss of engine power. He stopped the turn and noted that the engine was at flight idle as indicated by the dual tachometer. He verified the throttle was full open, and maneuvered the helicopter towards an open area. He bled off main rotor rpm to clear obstacles that were ahead, and decelerated at 10 feet above ground level. The helicopter touched down with little forward movement, coming to rest upright with the skids and tailboom separated. The helicopter was found to contain a sufficient quantity of fuel to sustain engine operation; no contaminants were reported. Examination of the engine revealed the fuel inlet line "B" nut was found loose by 2 1/2 flats at the fuel inlet nozzle. The fuel inlet line was drained and found to contain approximately 1 teaspoon of fuel while the fuel filter was full of fuel. The engine control rigging was found to be in limits. An abnormal sound was heard during testing of the aircraft fuel shutoff valve. Operational testing of the valve revealed it was operational but rotation of the valve body occurred with rotation of the valve. The engine was removed from the helicopter and transported to the manufacturer's facility. Prior to the engine run, the bleed air valve was found failed in the closed position; the internal spring was found unwound. The engine was operated in the presence of an FAA airworthiness inspector with a new bleed valve and the accident bleed valve installed; no appreciable difference was noted with respect to starting temperature, acceleration times, or stabilized operation. A customer bleed line that attaches to the scroll was found loose, it was tightened followed by engine operation. The line was loose when checked following the engine run. No significant findings were noted during the engine runs. Safety concerns prevented operation of the engine with the as-found position of the loose "B" nut at the fuel nozzle; however, a valve was installed to divert fuel from the fuel nozzle simulating the as-found position of the loose "B" nut. During the engine run, the valve was opened 1/4 and the engine operated normally. The valve was opened to 1/2 then 3/4, the engine continued to operate normally though the fuel flow increased. The valve was then fully opened and the engine flamed out. Several hours before the accident, a mechanic performed a compressor wash. It was common practice for the mechanic to clean the fuel nozzle when he performed a compressor wash.
The National Transportation Safety Board determines the probable cause(s) of this accident to be: The pilot's inadequate preflight of the helicopter following maintenance he observed, and failure of maintenance personnel to tighten the "B" nut at the fuel nozzle following a compressor wash resulting in the total loss of engine power. Also, the pilot's intentional decay of main rotor rpm while attempting to clear obstructions and unsuitable terrain encountered during the forced landing resulting in a hard landing. Full narrative available
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