On August 1, 2000, a Piper PA-25 (registration N6195Z) was involved in an aviation accident near Wildwood, NJ. Investigators recorded the probable cause as: The partial loss of power caused by detonation of the #3 piston. This summary draws on records from the U.S. National Transportation Safety Board (NTSB) historical archive.
A banner-towing pilot experienced engine power loss with smoke from the cowling and high oil temperature, performing an emergency landing in a field where the right wing struck a tree. Examination revealed a hole burned through the #3 cylinder from detonation.
Incident Overview
A pilot conducting a local banner-towing flight decided to return to the airport after 45 minutes. While en route, the pilot advanced the throttle to initiate a climb but received no response from the engine. The engine began losing power, and smoke appeared from under the cowling. The oil temperature gauge approached the red line, and the RPM gauge decreased, though the oil pressure remained constant at 80 psi.
Emergency Landing
The pilot performed an emergency landing in a field. After touchdown, the airplane struck a tree with its right wing.
Engine Examination
Post-incident examination of the engine revealed a hole burned through the top of the #3 cylinder, consistent with detonation. Advisory Circular AC65-12A notes that detonation can burn a hole completely through a piston.