On July 2, 1997, a Cessna T210M (registration N761FM) operated by Clyde F. Sanford Iii was involved in an aviation accident near Kerrville, TX. Investigators recorded the probable cause as: According to the manufacturer, the burning of the piston crown was most likely the result of either detonation or pre-ignition, though no discrepancies were found that would have caused such conditions. This summary draws on records from the U.S. National Transportation Safety Board (NTSB) historical archive.
An airplane experienced an engine power loss during climb, resulting in a forced landing in rough terrain. Examination revealed a seized piston, broken rings, and evidence of detonation or pre-ignition.
Accident Overview
During the climb to cruise altitude, the airplane's engine lost power. The pilot executed a forced landing short of the runway, touching down in rough and uneven terrain.
Engine Examination
Post-accident examination of the engine revealed severe damage to the number one cylinder. The piston was seized in the cylinder, with broken piston rings and a deteriorated piston head. The edge of the piston head was eroded down to the top compression ring, and a portion of that ring was missing. Metal deposits were found on the intake valve seat, and the intake valve was stuck in the open position. The cylinder dome was damaged, and scoring was present on the cylinder walls. Aluminum particles were embedded in the spark plugs, combustion chamber, and internal components of the number one cylinder.
Manufacturer's Analysis
The manufacturer examined the engine components and found no discrepancies that would have caused detonation or preignition in the number one cylinder. The cylinder met SAE chemistry requirements. The manufacturer's metallurgist stated that the burning of the piston crown was most likely the result of either detonation or preignition.
Probable cause
According to the manufacturer, the burning of the piston crown was most likely the result of either detonation or pre-ignition, though no discrepancies were found that would have caused such conditions.