What happened
On September 23, 2013, a Cirrus Design Corp SR22, registration N426TF, was en route from Alamosa, Colorado, to Ogden, Utah, when the engine suddenly lost power. While flying at approximately 12,500 feet, the pilot reported a reduction in fuel flow followed by a complete engine seizure.
The pilot attempted an emergency landing at Mack Mesa Airport (C07) on runway 25. During the landing, the aircraft overran the end of the runway and encountered a large drop-off in the terrain, which caused the airplane to become airborne again. The pilot then maneuvered to avoid power lines and attempted a second landing on a road, where the aircraft struck a ditch. The aircraft sustained substantial damage. The pilot sustained one minor injury, while the two passengers were not injured.
The investigation
Data from the aircraft's Recoverable Data Module (RDM) confirmed that engine power dropped from 82 percent to 49 percent before rapidly falling to 0 percent power and 0 rpm.
An examination of the engine revealed that the crankshaft had fractured through the cheek between the No. 2 main bearing journal and the No. 3 connecting rod journal. Investigators found that the No. 2 main bearings had extruded from their positions and showed mechanical damage. Additionally, the No. 2 main bearing support showed signs of bearing shift, and several bearing saddle supports exhibited fretting.
Maintenance records indicated that approximately 18 months prior to the accident, the Nos. 1, 2, 3, and 4 cylinders had been replaced. Because the through case bolts also serve as cylinder hold-down bolts, the nuts on these bolts had to be removed to complete the cylinder replacement.