NTSB Identification: NYC07LA125
14 CFR Part 91: General Aviation
Accident occurred Wednesday, May 23, 2007 in Leesburg, VA
Probable Cause Approval Date: 12/24/2008
Aircraft: CESSNA 172E, registration: N3982S
Injuries: 1 Minor.
NTSB investigators may not have traveled in support of this investigation and used data provided by various sources to prepare this aircraft accident report.
The pilot was relocating a Cessna 172E for the airplane's annual maintenance inspection. During the flight, the engine suffered a partial loss of power and began to "shake and misfire violently." The pilot then attempted to control the engine by adjusting the throttle and mixture controls, without result. As the airplane descended, the pilot looked for a place to land and spotted an open field. After turning final, he extended his wing flaps to the 40-degree position and touched down. During the emergency landing the airplane approached a ditch. The pilot attempted to get over the ditch by raising the flaps, but the airplane struck the far side of the ditch. During a postaccident examination of the engine, it was discovered that the No.2 cylinder's exhaust valve rocker arm was fractured and had separated into two parts. The initial fracture on the exhaust valve rocker arm was on the push rod side of the arm. This fracture had features indicative of overstress. The fracture on the valve side of the arm was secondary to the overstress fracture on the push rod side. The fatigue cracking at this location appeared to be the result of bending loads generated after the fracture on the push rod side was created. The fracture on the push rod side of the arm was generated from some type of high load event, possibly during an overhaul 34.8 hours prior to the accident. The pilot/owner had purchased one of the cylinders on "eBay," and there were discrepancies in the engine maintenance records.
The National Transportation Safety Board determines the probable cause(s) of this accident to be: The loss of engine power that resulted from the failure of an exhaust valve rocker arm during cruise. Full narrative available
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