On June 20, 1997, a Schweizer G-164B (registration N6816Q) was involved in an aviation accident near Edwards, MS. Investigators recorded the probable cause as: Right magneto distributor drive gear failure resulting in loss of magneto timing. This summary draws on records from the U.S. National Transportation Safety Board (NTSB) historical archive.
During an aerial application pull-up, the engine lost power. The pilot performed a forced landing in a field but could not stop before hitting trees. Investigation revealed a failed right magneto distributor drive gear.
Incident Overview
An agricultural aircraft experienced an engine power loss while pulling up from an aerial application run. The pilot immediately executed a forced landing in a nearby open field. However, the aircraft could not be stopped before it collided with trees at the far end of the field.
Postcrash Examination
A postcrash inspection of the engine identified a failure of the right magneto distributor drive gear. Several teeth on the gear were found missing, causing the gear to occasionally fail to drive the distributor. This resulted in a loss of timing between the magneto and the engine.
Pilot Statement
The pilot reported that there was insufficient time to cycle the magneto switches during the emergency before the forced landing was carried out.
Findings
The investigation determined that the engine power loss was due to a magneto timing loss, which was caused by the failure of the right magneto distributor drive gear with missing teeth.
Probable cause
Right magneto distributor drive gear failure resulting in loss of magneto timing.