MT MCKINLEY VIL, AK, USA
N1078N
BELL 206L-1
THE HELICOPTER EXPERIENCED AN ENGINE FAILURE WHILE CRUISING AT ABOUT 600 FT AGL. THE PILOT MADE A FORCED LANDING DURING WHICH THE MAIN ROTOR BLADES COLLIDED WITH TREES. EXAMINATION OF THE AIRCRAFT FUEL SYSTEM REVEALED THAT THE CHECK VALVES LOCATED IN THE FUEL LINES WHICH TRANSFER FUEL FROM THE FORWARD FUEL CELL TO THE AFT FUEL CELL WERE WORN AND ONE OF THE CHECK VALVES WAS STUCK IN THE CLOSED POSITION. FURTHER EXAMINATION OF THE FUEL MANIFOLD, WHICH CONTAINS TWO MORE POPPET VALVES, REVEALED THAT ONE OF THE POPPET PARTICLES WAS FOUND IN ALL OF THESE CHECK VALVES. WITH BOTH POPPET VALVES CLOSED, THE FUEL BOOST PUMPS WILL NOT SUPPLY PRESSURE TO THE SINGLE FUEL LINE, TO THE FUEL PRESSURE TRANSDUCER OR TO THE ENGINE.
Source: NTSB Aviation Accident Database
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