On May 27, 1997, a Piper PA-25-235 (registration N4829Y) was involved in an aviation accident near Lamar, CO. Investigators recorded the probable cause as: Failure of the left magneto and crank shaft idler drive gears. Factors were failure to perform a 100 hour inspection and unsuitable terrain for a forced landing. This summary draws on records from the U.S. National Transportation Safety Board (NTSB) historical archive.
During an aerial application swath run, the engine lost all power, forcing a landing in a field with high vegetation. Post-accident examination revealed failure of the left magneto drive gear and crankshaft idler gear; aircraft records showed over 247 hours since last 100-hour inspection.
Accident Summary
The incident took place while the aircraft was performing a swath run for aerial application. During this run, the engine lost all power. The pilot subsequently conducted a forced landing in a field that was covered with high vegetation, which rendered the field unsuitable for a forced landing.
Engine Examination
After the accident, the engine was examined. The inspection provided evidence that both the left magneto drive gear and the crankshaft idler gear had failed. The examination specifically identified these components as having failed.
Aircraft Records
An examination of the aircraft's records revealed that the aircraft had accumulated over 247 hours of operation since its last 100-hour inspection. Additionally, the records indicated that an Airworthiness Directive applicable to the magnetos had been complied with.