Accident Details
Probable Cause and Findings
the student pilot's use of an excessively lean mixture, which led to engine overheating, detonation, subsequent failure of the number 2 piston, and a forced landing.
Aircraft Information
Registered Owner (Historical)
Analysis
On October 15, 1996, at 1005 hours Pacific daylight time, a Cessna 172P, N6187K, operated by the Sierra Academy, Inc., Livermore, California, made a forced landing in a field near Kingsburg, California. The airplane was destroyed during landing rollout upon colliding with a tree and a building. The student pilot received minor injuries. Visual meteorological conditions prevailed, and a visual flight rules flight plan was filed for the student's third solo instructional cross-country flight. The flight originated from Livermore about 0900.
The Federal Aviation Administration (FAA) reported that while the pilot was cruising at 5,500 feet mean sea level the engine suddenly began running rough and oil was observed covering most of the front windscreen. Engine power was subsequently lost and the pilot made a forced landing.
The FAA performed an examination of the wreckage and observed a 2-inch diameter hole in the engine's upper case in the vicinity of the number 2 cylinder. A further examination revealed that the connecting rod to the number 2 piston was disconnected from the piston due to the failure of the piston skirt in the piston pin area. The rings in all pistons appeared to have been sticking, with over temperature signatures noted on all the intake and exhaust valves. The tops of each piston were abnormally clean.
The engine was installed in the airframe on June 9, 1993. By the accident date, it had a total time of 3,794.5 hours, and 1,987.0 hours since last major overhaul.
Data Source
Data provided by the National Transportation Safety Board (NTSB). For more information on this event, visit the NTSB Records Search website. NTSB# LAX97LA018