Event Summary
A pilot reported experiencing a complete loss of engine power while cruising at 9,500 feet mean sea level. Attempts to restart the engine were unsuccessful. The pilot selected a field for a forced landing and maneuvered the airplane to a 'low key' position abeam the intended landing point at 1,200 feet above ground level. After extending the landing gear, the pilot noticed a tower in the field while at the 90-degree position to the landing point. To avoid the tower and its supporting guy wires, the pilot withheld flap extension and executed a zoom climb. The airplane subsequently stalled at approximately 20 feet above ground level at an indicated airspeed of 65 miles per hour.
Engine Examination
A teardown and inspection of the engine revealed that the camshaft gear drive attachment bolts had fractured. A metallurgical examination determined that the bolts failed due to fatigue. The metallurgist reported that evidence of fatigue failure was exhibited by beach marks and ratchet marks on the fracture surfaces. The markings suggested that the bolts had been under torqued during installation, which led to the fatigue failure.
Findings
The investigation determined that the loss of engine power resulted from the fatigue failure of the camshaft gear drive attachment bolts. The pilot's subsequent actions in avoiding the tower were consistent with standard procedures, but the stall occurred during the maneuver.