Incident Description
A student pilot was cruising at 5,500 feet mean sea level when the engine experienced a partial loss of power. The engine's revolutions per minute (rpm) surged and became "very erratic," resulting in reduced power. The pilot applied carburetor heat and performed troubleshooting steps but was unable to restore engine power. He executed a precautionary landing at a nearby airport. The approach speed was faster than normal, leading to a hard touchdown and a bounce. The student pilot then lost directional control, causing the airplane to veer off the runway and nose over in a tomato field approximately 50 yards beyond the side of the runway.
Maintenance and Logbook Findings
The operator maintained the airplane under a program of annual and 100-hour inspections. The most recent 100-hour inspection had been performed approximately 35 flight hours before the accident flight. A post-accident examination of the aircraft's logbooks revealed record-keeping deficiencies. Specifically, recording errors related to the airplane's operating time were noted, and compliance entries for airworthiness directives were omitted. Additionally, an examination of the engine uncovered evidence of inadequate maintenance. One spark plug was found to be only finger tight, a cylinder exhibited signs of excessive oil on its spark plugs and appeared not to be firing. All four bottom spark plugs had excessive carbon buildup and were fouled. The intake air filter was dirty and partially plugged.
Cause Determination
Despite the examination, no sole cause for the loss of engine power was ascertained.