NTSB Identification: FTW94GA204.
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Accident occurred Monday, June 20, 1994 in LONDON, TX
Probable Cause Approval Date: 01/26/1995
Aircraft: HUGHES 269C, registration: N7404F
Injuries: 2 Minor.
: NTSB investigators either traveled in support of this investigation or conducted a significant amount of investigative work without any travel, and used data obtained from various sources to prepare this public aircraft accident report.
DURING A COYOTE ERADICATION FLIGHT, THE AIRCRAFT EXPERIENCED A PARTIAL POWER LOSS. THE PILOT STATED THAT WHILE HE WAS MANEUVERING AT LOW ALTITUDE AND AIRSPEED, HE FELT A VIBRATION THROUGH THE AIRFRAME, THE ENGINE AND MAIN ROTOR RPM BEGAN TO DECREASE, AND THE NEEDLES SPLIT. HE APPLIED FULL POWER, BUT THE ENGINE WOULD ONLY DEVELOP 2,000 RPM. WHILE THE PILOT WAS MANEUVERING TO A CLEAR AREA, THE MAIN ROTOR BLADES STRUCK TREES AND THE AIRCRAFT ROLLED TO THE RIGHT AND IMPACTED THE GROUND. FOLLOWING THE ACCIDENT, THE ENGINE WAS TEST RUN IN THE AIRFRAME AND FOUND TO BE RUNNING ROUGH. INVESTIGATION REVEALED THAT THE ENGINE CAMSHAFT LOBES WERE WORN BEYOND LIMITS AND THE #4 EXHAUST VALVE WAS HEAT DISCOLORED AND SHOWED SIGNS OF STICKING.
The National Transportation Safety Board determines the probable cause(s) of this accident to be: THE PARTIAL POWER LOSS DUE TO A STICKING VALVE. FACTORS WERE THE REMAINING WORN LOBES ON THE CAMSHAFT AND THE LACK OF SUITABLE TERRAIN ONTO WHICH A SUCCESSFUL FORCED LANDING COULD BE EXECUTED. Full narrative available
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