On July 26, 1990, an Air Tractor AT-401 (registration N7315S) operated by Grouleff Aviation, Inc. was involved in an aviation accident near San Joaquin, CA. Investigators recorded the probable cause as: THE FAILURE OF THE NO. 4 CYLINDER HEAD. This summary draws on records from the U.S. National Transportation Safety Board (NTSB) historical archive.
A pilot experienced an engine failure during aerial application, landed in a field, and the aircraft flipped over. The pilot died from positional asphyxia. Examination found a cracked cylinder.
Accident Overview
During an aerial application flight, the pilot encountered an engine failure. The pilot executed a landing in a field, but during the landing the aircraft flipped over. The aircraft remained structurally intact, and no fire occurred. The pilot subsequently died due to positional asphyxia.
Engine Examination
Following the accident, an examination of the engine was conducted. The inspection revealed that the No. 4 cylinder was cracked around the cooling fins, with the crack extending through the center of the spark plug boss. The engine had accumulated 7,251 total operating hours and 339 hours since its most recent overhaul.