Accident Overview
On August 27, 2009, at approximately 0730 mountain standard time, a Cessna 210K, registration N4600Q, executed a forced landing after a loss of engine power about 6 nautical miles west of Show Low Regional Airport (SOW) in Show Low, Arizona. The airline transport pilot and sole passenger were not injured. Visual meteorological conditions prevailed for the cross-country flight, which was conducted under 14 Code of Federal Regulations Part 135. A VFR flight plan had been filed but not activated. The flight departed Flagstaff Pulliam Airport (FLG) at about 0650 and was destined for SOW.
According to the pilot's written statement, while cruising at 9,500 feet mean sea level, the engine oversped to the redline. After reducing propeller rpm to the green arc, the oil pressure gauge indicated zero. The pilot declared an emergency while approximately 20 nautical miles northwest of SOW. About two minutes after observing the anomalies, the engine lost power. Approximately two minutes later, the engine failed and seized, the propeller stopped, the oil filler door opened, and smoke filled the cabin. The pilot selected an open meadow for a gear-up landing. The airplane sustained damage to the engine firewall and belly skin.
Engine Examination
The Teledyne Continental IO520L14 engine (serial number 295481-R) was shipped to Teledyne Continental Motors Analytical Department in Mobile, Alabama, for examination. The examination was conducted by a Teledyne engine technician and overseen by an FAA inspector. Findings included a large dark stain in the oil sump covered with a gray epoxy substance. The engine was equipped with a Supplemental Type Certificate (STC SE09356SC) oil filter adapter. A gasket between the oil filter adapter and oil pump housing was displaced and showed dark stains. The vacuum pump housing was coated with a dark glaze, and oil was found between the vacuum pump mounting flange and gasket. The crankshaft exhibited lubrication distress, thermal damage, and mechanical damage. Connecting rod bearings showed various degrees of lubrication distress and thermal damage, and the number 3 crankshaft main bearing also displayed lubrication distress.
Maintenance History
Maintenance records indicated the engine was manufactured on November 28, 2007, and underwent a 100-hour inspection on August 20, 2009, at a total time of 352.9 hours. At the accident time, the engine had accumulated 4.7 hours since that inspection.
Further review showed that on April 24, 2008, at 160.0 hours, an STC oil filter adapter (model C6LC-L) was installed. The installation instructions specified using a fiber gasket without gasket compounds or glues, torquing the adapter to 65 lbs./ft., and re-torquing after 10 hours of operation. In an interview, the FAA-certificated mechanic who performed maintenance stated he used no sealant on the gasket, as per STC instructions. He reported re-torquing the adapter as required but could not produce a record. The mechanic also noted he had been troubleshooting an oil leak and, on advice from a Continental representative, used RTV on the oil pan (not on the oil filter adapter) to eliminate the leak. He stated he used a new gasket from F&M Enterprises when installing the engine and oil filter adapter.