Incident Overview
The airplane experienced a loss of engine power while in cruise flight on a dark night. The pilot was in contact with the local Terminal Radar Approach Control (TRACON) facility and reported the situation. The pilot indicated being in-between airports and decided against turning back to the departure airport due to the dark night and mountainous terrain conditions. After reporting the power loss, radio contact with the controller was lost. The pilot then attempted a landing on the desert floor. The airplane was landed with the landing gear retracted and struck desert shrubbery, causing structural damage.
Engine Performance and Pilot Observations
The pilot reported that the engine sounded as if it had lost a cylinder or a valve and was running "weakly." A review of the airplane's logbooks revealed that it had flown 14 hours since the last 100-hour/annual inspections. The factory-remanufactured engine had been installed on June 15, 2001, and had accumulated a total time of 717 hours.
Engine Teardown and Metallurgical Examination
An engine teardown was performed, and investigators noted that several camshaft gear teeth were missing, some of which were found in the oil sump. A metallurgical examination of the camshaft gear and teeth revealed signatures consistent with normal wear. Many surfaces on the camshaft gear had been damaged due to continued operation after the teeth separation. A fracture surface at the site of a missing tooth showed evidence of fatigue initiating at the surface. The metallurgist noted surface marks at the root on both sides of each tooth. Hardness tests between the gear teeth on both parts were found to meet component specifications based on the R30N scale.