Accident Details
On May 5, 2014, at approximately 1330 mountain daylight time, a Cessna T207A, registered as N323JC, sustained substantial damage during a forced landing following a reported loss of engine power. The incident occurred near the Rock Springs-Sweetwater County Airport (RKS) in Rock Springs, Wyoming. The aircraft was registered and operated by Aero-Graphics Inc. under 14 CFR Part 91. The commercial pilot and passenger were not injured. Visual meteorological conditions prevailed, and no flight plan was filed for the business flight. The flight originated from Evanston-Uinta County Airport-Burns Field, Evanston, Wyoming, at 1200, with a destination of RKS.
The pilot reported that during cruise flight at about 9,500 feet mean sea level, the engine stopped and could not be restarted. Realizing that the airport was unreachable, the pilot executed a forced landing to a nearby clearing. The airplane came to rest upright in a field approximately 15 miles north of RKS.
Engine Examination
Initial examination by a Federal Aviation Administration inspector revealed substantial damage to the engine firewall. The aircraft was recovered to a local storage facility for further inspection. A certified Airframe and Powerplant mechanic examined the engine under the oversight of the National Transportation Safety Board investigator-in-charge and an FAA inspector.
The examination found the engine intact with all accessories attached. Rocker covers and spark plugs were removed; cylinder overhead components were lubricated and undamaged. The engine could not be rotated by hand. The oil filter was contaminated with metal particles. Cylinders were removed; break-away through bolt torque indicated that cylinder numbers 1 and 2 had improperly torqued through bolts. The number 2 cylinder piston was labeled as an IO-550 piston, intended for a naturally aspirated engine, while all other pistons were correctly labeled for the turbocharged engine.
Further disassembly revealed oil and metal particles on interior surfaces. The crankshaft had separated at the number 2 cheek, aft of the number 2 main bearing journal. Substantial internal damage was present in the area of the number 2 main bearing, which had separated from its bearing support. The main support mating surfaces showed fretting. The number 2 cylinder bay had mechanical damage. The number 2 main bearing support aft facing surface displayed metal deformation consistent with bearing shedding. The bearing support lock tab showed lateral movement and lock slot elongation, and the support had metal deformation along its edges.
Maintenance History
A review of maintenance records indicated that the engine was overhauled on February 17, 2011, at an engine total time of 4,985 hours. The number 2 cylinder was removed and replaced on October 25, 2012. A top overhaul was performed on May 23, 2013. The number 3 cylinder was removed and replaced on July 11, 2013. The number 1 cylinder was removed and replaced on January 17, 2014; at that time, the connecting rod was removed and repaired, and the nose seal was replaced. The aircraft had logged 94.5 hours since the number 1 cylinder removal and replacement.