CEN11LA101

While in the traffic pattern at the destination airport, the pilot experienced a loss of engine power on the left engine followed by a loss of engine power on the right engine. The pilot reported that there was not enough airspeed or altitude to reach the airport so he performed an off-field landing resulting in substantial damage to the airplane. The pilot reported that he had encountered a loss of engine power on both engines on two previous occasions. Both events were preceded by the reduction of engine power under rich mixture conditions. An examination of the left and right engines, and right side fuel system revealed no anomalies. The left fuel tank and fuel system were damaged by the fire and could not be examined for continuity. Data recovered from the engine monitor illustrated a decrease in exhaust gas temperature on the right engine approximately one minute prior to the decrease of exhaust gas temperature on the left engine. The reason for the loss of engine power on both engines could not be determined.

On December 3, 2010, approximately 1740 central standard time, a twin-engine Beech 95-C55 airplane, N211DS, was substantially damaged during a forced landing near Claremore Regional Airport (KGCM), Claremore, Oklahoma. A post impact fire ensued. Night visual meteorological conditions prevailed at the time of the accident. The personal flight was being conducted under the provisions of 14 Code of Federal Regulations Part 91 on an instrument flight rules flight plan. The pilot sustained serious injuries and his passenger sustained minor injuries. The flight departed Jacksonville, Texas, approximately 1610 and was en route to KGCM. In a written statement submitted by the pilot, he had just reduced the engine power, while turning to final for runway 17, when the left engine lost power. As he started to prepare for single engine operations, the right engine lost power. The pilot reported that there was not enough airspeed or altitude to reach the airport so he performed an off-field landing. He stated that prior to the reduction in power, the fuel selector valves were selected to the main tanks, the fuel boost pumps were off, the mixture was set at rich, and all four fuel tanks indicated "adequate fuel." According to a Federal Aviation Administration (FAA) airworthiness inspector who traveled to the scene, the left wing separated from the airplane and had burned. The empennage separated from the airframe and was located in the debris field. The team that recovered the wreckage reported that the right main fuel tank was full of fuel, and the left main fuel tank was burnt with signatures consistent with a fuel fed fire. Both auxiliary fuel tanks were empty. The pilot wrote that he had encountered a loss of engine power on both engines within the preceding few months. One event was experienced while the airplane was at 18,000 feet and the second event was experienced when the airplane was below 2,000 feet. Both events were preceded by the reduction of engine power under rich mixture conditions. The pilot felt that in both cases the root cause of the problem was never identified and was related to "fuel delivery that exceeds that required for stable combustion." Both engines had been modified with a Merlyn Products turbonormalizing system (Supplemental Type Certificate Number SA01663SE). An examination of the right engine revealed residual fuel in the fuel lines and signatures of normal operation on the spark plugs when compared to the Champion Spark Plug chart. The engine was rotated through by hand and valve movement was observed and air movement was heard on all six cylinders. Both magnetos were manually rotated and produced a blue spark at all leads. An examination of the right fuel tank and fuel system revealed no anomalies. The right fuel selector valve was tight, illustrated specific detent positions, and functioned as designed when tested with shop air. The left engine exhibited extensive impact and fire damage. The damage prevented the rotationof the engine and magnetos. The spark plugs exhibited signatures of normal operation when compared to the Champion Spark Plug chart. The left fuel tank and fuel system were damaged by the fire and could not be examined for continuity. The left fuel selector valve did not demonstrate specific detent positions, but functioned as designed when tested with shop air. Further examination revealed tape securing one ball bearing within the valve's yoke assembly. The second ball bearing was missing. The airplane was equipped with a fuel flow indicator, two oil pressure and temperature gauges (for the right and left engines respectively), and an engine monitor, all containing non-volatile memory. The units were shipped to the National Transportation Safety Board Vehicle Recorders Laboratory for data recovery. Details on these units and the recovered data is available in the engine instruments factual report available with this accident report docket. The fuel flow indicator recorded 66.8 gallons of fuel remaining, based upon the information loaded by the pilot prior to the flight. Data recovered from the engine monitor illustrated a decrease in exhaust gas temperature on the right engine approximately one minute prior to the decrease of exhaust gas temperature on the left engine. The two oil pressure and temperature gauges illustrated a decrease in oil pressure and temperature towards the end of the recorded data; however, due to the lack of a time stamp with this data, a correlation could not be performed. The reason for the loss of engine power on both engines could not be factually determined.