Beech 23 N2339J accident near Humboldt, Tennessee

Probable cause

A partial loss of engine power due to low No. 2 cylinder compression and an inoperative right magneto.

NTSB analysis

The student pilot and flight instructor reported that ground operations were normal. During the initial climb, when the airplane was about 950 ft above ground level, the engine lost partial power. Unable to return to the departure airport, the flight instructor performed a forced landing in a field. During the landing roll, the nose gear collapsed, which resulted in substantial damage to the airframe.

A postaccident examination of the engine revealed that the No. 2 cylinder only produced minimal compression and that the intake valve would not seat fully due to carbon deposits. The No. 2 cylinder exhaust pipe flange was separated from the cylinder exhaust seat face by about 0.25 inch on the outer left side, and the stud was missing the nut and both washers. One of the spark plugs had lead deposits and produced a weak spark when tested. Also, the right magneto was inoperative; the permanent magnet breaker end bearing had failed, and six teeth were missing from the large distributor timing gear. The partial loss of engine power was likely the result of both the low No. 2 cylinder compression and an inoperative right magneto.

Text from the NTSB. Open the NTSB docket for ERA16LA019 for the full record.