NTSB Identification: DEN99LA015.
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Accident occurred Wednesday, October 21, 1998 in ENGLEWOOD, CO
Probable Cause Approval Date: 02/16/2001
Aircraft: Mooney M20C, registration: N6405U
Injuries: 1 Serious.

NTSB investigators may not have traveled in support of this investigation and used data provided by various sources to prepare this aircraft accident report.

During climb following departure, the engine lost power. The pilot reported the emergency to the tower and attempted to return to the airport. Determining that he would be unable to make it back, he made an emergency landing in a field one and a half miles southeast of the airport. Postaccident examination of the engine revealed that the camshaft gear retaining bolts connecting the camshaft gear to the camshaft had lost torque. As a result, the lobes failed to open their respective valves, creating discontinuity to the gear train. The tread on each of the four camshaft gear bolts exhibited shiny, worn patterns. According to a Textron Lycoming engineer, loss of camshaft retaining bolt torque is indicative of the bolts being improperly torqued during the engine overhaul. According to aircraft maintenance records, the engine was overhauled on March 15, 1985, and had accumulated 833 hours since overhaul.

The National Transportation Safety Board determines the probable cause(s) of this accident to be:

The undertorquing of the camshaft gear retaining bolts during engine overhaul by maintenance personnel. A factor was the unsuitable terrain for a forced landing.

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