2013 Cirrus SR22 Accident at Mack Mesa Airport (N426TF)

Accident Overview and Flight Details On September 23, 2013, a Cirrus Design Corp SR22, registration N426TF, sustained substantial damage during a forced landing at Mack Mesa Airport (C07) in Mack, Colorado. The aircraft, a private business flight operating under 14 CFR Part 91, had departed from San Luis Valley Regional Airport in Alamosa, Colorado, at approximately 1617 local time. It was en route to Ogden-Hinckley Airport in Ogden, Utah, when the incident occurred. The pilot and two passengers were on board; the pilot sustained minor injuries, while the passengers were unharmed. ## Sequence of Events During cruise, the pilot reported that the engine suddenly lost power and fuel flow reduced at an altitude of 12,500 feet, about 7 to 8 miles northeast of the airport. The pilot attempted to increase fuel flow, but the engine seized. A restart attempt failed as the engine would not rotate. The pilot diverted to Mack Mesa Airport and attempted a landing on runway 25. The aircraft landed long and overran the runway, becoming airborne again due to a large drop-off at the departure end. The pilot maneuvered to avoid power lines and attempted a landing on a road, where the aircraft struck a ditch and sustained damage. ## Recorded Data and Engine Examination The aircraft was equipped with a Heads Up Technologies Recoverable Data Module (RDM) that recorded flight and engine data at a 1 Hertz rate. The data confirmed the pilot's account. At 1723:39, the aircraft was at 12,190 feet pressure altitude with 82 percent engine power at 2,522 rpm. By 1727:29, power had reduced to 49 percent at 2,524 rpm. Power briefly restored to 89 percent at 2,206 rpm at 1727:41, then rapidly dropped to 0 percent power and 0 rpm at 17:30:00. The aircraft came to rest at 1735:44. Following the accident, the engine was removed for a teardown examination. The examination revealed a fracture through the crankshaft at the cheek going from the No. 2 main bearing journal to the No. 3 connecting rod journal. The No. 2 main bearings had extruded from their crankcase positions and exhibited mechanical damage. The No. 2 main bearing support displayed signatures consistent with bearing shift, and the No. 2 main bearing saddle supports and several other bearing saddle supports exhibited fretting. ## Maintenance History A review of the maintenance records indicated that on April 13, 2012, cylinders 1, 2, 3, and 4 were removed and replaced due to cracking in the injector boss area. The through case bolts adjacent to the No. 2 main bearing journal also serve as hold down bolts for cylinders 2 and 3. To remove the cylinders, it was necessary to remove the nuts from the through bolts.