CEN13LA370

The pilot stated that the engine abruptly lost power while he was practicing instrument approaches under visual flight rules. His efforts to restore engine power were unsuccessful. The pilot subsequently executed a forced landing to the center median of a roadway. A postaccident examination revealed that the dual magneto assembly was not functioning properly. Although the magneto drive shaft operated during engine crankshaft rotation, the magneto points did not open as required. A teardown examination revealed that the magneto components were worn. In addition, the threaded inserts had lifted out of the mounting block. The magneto assembly was inspected less than 1 flight hour before the accident during an engine propeller strike inspection, and the magneto block, points, and cam were replaced at that time. The accident flight was the second flight since the inspection and maintenance work had been performed. Although the magneto points might have been misaligned due to the threaded insert lifting out of the mounting block, it is unlikely that such a discrepancy would have resulted in a loss of magneto function within such a short timeframe. The magneto failure caused the loss of engine power; however, the cause of the magneto failure could not be determined.

On June 25, 2013, about 0825 central daylight time, a Mooney M20J airplane, N205MC, was substantially damaged during a forced landing following a loss of engine power near El Reno, Oklahoma. The pilot and passenger were not injured. The aircraft was registered to PWH-Air, LLC and operated by the pilot under the provisions of 14 Code of Federal Regulations Part 91 as a personal flight. Visual meteorological conditions prevailed for the flight, which was not operated on a flight plan. The local flight originated from Wiley Post Airport (PWA), Bethany, Oklahoma, at 0730. The pilot stated that he was conducting practice instrument approaches under visual flight rules to the El Reno Regional Airport (RQO) when the engine lost power completely with "no sputtering, no coughing, no warning." The pilot's efforts to restore engine power were not successful. He ultimately executed a forced landing to the center median of a roadway. During the landing, the airplane encountered a drainage ditch, which caused the left main landing gear to separate and the nose landing gear to collapse. A postaccident examination of the single drive shaft, dual magneto assembly was conducted by a Federal Aviation Administration inspector. The examination revealed that the dual magneto was not functioning properly. Although, the magneto drive shaft operated during engine crankshaft rotation, the magneto points did not open as required. Further examination noted that the magneto components were worn.At the time of the accident, the airframe and engine had accumulated about 2,600 hours total time, with approximately 435 hours since engine overhaul. The most recent annual inspection was completed in September 2012. However, an engine propeller strike inspection was reportedly conducted less than one flight hour before the accident. The dual magneto assembly was inspected at that time. The accident flight was the second flight since that inspection and maintenance work had been performed. The pilot reported that the magneto block, points and cam were replaced at the time of the magneto inspection. He added that the threaded inserts appeared to have lifted out of the mounting block about 1/32 inch, which would have changed the orientation of the points and possibly caused the excessive wear.