Accident Details
On September 10, 2010, at about 1315 eastern daylight time, a Cessna 150, registration N7922E, operated by a private individual, incurred substantial damage during a forced landing following a partial loss of engine power shortly after takeoff from Fayette Airport (WV59), Fayetteville, West Virginia. The airline transport rated pilot and a private pilot passenger received serious injuries. Visual meteorological conditions prevailed for the personal flight conducted under Title 14 Code of Federal Regulations Part 91.
Pilot Narrative
The pilot reported that the preflight and ground run prior to flight were unremarkable. During the initial climb, the engine tachometer indicated 1900 rpm, and the airplane would not gain altitude. He elected to land in a field, and the airplane collided with trees before impacting the ground. The pilot was able to call for assistance, and both pilots were taken to the hospital due to their injuries.
Aircraft Examination
A Federal Aviation Administration inspector examined the airplane after recovery. Fuel was found in the fuel tanks and up to the carburetor system. All cylinders had compression when checked. The right magneto developed sparks to all corresponding plugs, while the left magneto produced spark to only one plug. The magnetos, carburetor, and spark plugs were retained for further testing.
Maintenance Records
A review of the aircraft maintenance records showed that the last annual inspection was on April 27, 2010, at a total of 2,512 hours. The magnetos were previously inspected on August 11, 1994, at 2,418 total hours; March 6, 1996, at 2,422 total hours; and October 14, 2002, at 2,459 total hours.
Magneto Examination
Examination of the left magneto, under National Transportation Safety Board oversight, revealed that its exterior appearance was consistent with having been in service for a length of time. No exterior damage was observed, and the magneto rotated when turned by hand, but internal discrepancies were noted. Upon disassembly, the distributor gear was found with 12 gear teeth sheared from the disk; the sheared gears were recovered within the magneto assembly. The separation began and ended at the magneto timing block location marker. The distributor cap showed indications of arcing between the housing areas. The coil and condenser were tested and found unremarkable.
Airworthiness Directives
It was noted that the magnetos were required to have the riveted style impulse coupling checked every 100 hours in service as per Airworthiness Directives (AD) 78-09-07, AD 96-12-07, and AD 2005-12-06. This was identifiable by the missing mark "A" in the lower right corner of the magneto data plate. Any time after 1978, when the magneto was opened for a riveted impulse coupling examination, the distributor gear was required to be replaced with an updated distributor gear if not previously done, as per Teledyne Continental Ignition Systems Service Bulletin 658. Both magnetos had the old style distributor gear dating prior to 1978. Service Bulletin 658 includes a warning not to use any gear holding tool, as this may cause hidden damage to the distributor gear and subsequent engine failure.