On June 23, 2004, an Air Tractor AT-401 (registration N1013N) was involved in an aviation accident near Britton, SD. Investigators recorded the probable cause as: The loss of engine power due to a stuck exhaust valve and the unsuitable terrain encountered during the forced landing. A factor to the accident was the soft terrain condition. This summary draws on records from the U.S. National Transportation Safety Board (NTSB) historical archive.
An aerial-application airplane nosed over during a forced landing into soft terrain after the engine lost power. The pilot reported rough engine operation prior to the landing.
Accident Overview
An aerial-application airplane impacted soft terrain and nosed over during a forced landing following a loss of engine power.
Pilot Report
The pilot reported that the engine began running rough after he completed his spraying and was returning to the departure airport. The pilot stated he eventually had to perform a forced landing into a soft field, during which the airplane nosed over.
Engine Examination
The engine was inspected following the accident. The shaft mount for the number eight cylinder rocker-arm was found to be cracked and separated. This damage is consistent with damage caused by a stuck exhaust valve.