NTSB Identification: FTW99LA110.
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Accident occurred Wednesday, April 07, 1999 in TURRELL, AR
Probable Cause Approval Date: 09/12/2000
Aircraft: Cessna 172N, registration: N5171K
Injuries: 2 Uninjured.
NTSB investigators may not have traveled in support of this investigation and used data provided by various sources to prepare this aircraft accident report.
While maneuvering at a low altitude, there was a loss of engine power. During the forced landing to a rough/uneven road, the airplane's right main tire exited the road into a muddy ditch. The airplane nosed down in the adjacent soft field. Postaccident investigation revealed that the #1 cylinder intake valve rocker assembly stud bolt was backed out of the hole four turns, allowing the valve to become inoperative. Lycoming service bulletin 412B issued in March 1978, for replacing all rocker arm retaining studs with oversized studs was complied with at the factory before engine S/N L-7296-76 was shipped to Cessna in 1979. The original logbooks were reported lost; therefore, the complete history of the engine could not be verified. A review of reconstructed logbooks revealed that on February 12, 1998, the engine had accumulated '200 to 300 hours' since major overhaul. A 100-hour inspection maintenance entry for September 24, 1998, stated in part: 'Removed #1 cylinder, honed and installed new rings. #1 compression checked 68/80 at ground run. This engine determined to be in an airworthy condition.'
The National Transportation Safety Board determines the probable cause(s) of this accident to be: The total loss of engine power as the result of improper maintenance which led to the number one cylinder intake valve rocker assembly stud bolt backing out rendering the valve inoperative. A factor was the lack of suitable terrain for the forced landing. Full narrative available
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