On July 17, 2003, an Ayres Corporation S2R-G10 (registration N3299A) operated by Peterson Aerial Spraying was involved in an aviation accident near Staples, MN. Investigators recorded the probable cause as: The fatigue fracture of the oil jet flange resulting in a total engine failure during the aerial application. This summary draws on records from the U.S. National Transportation Safety Board (NTSB) historical archive; 1 related events involving the same aircraft type or operator are linked below.
An agricultural airplane sustained substantial damage during a forced landing after the engine stopped due to low oil pressure. Investigation found a separation in the oil jet flange consistent with high cycle fatigue.
Accident Sequence
An agricultural airplane was conducting an aerial application flight when the pilot observed low oil pressure indications on the instruments. Approximately five seconds later, the propeller automatically feathered and the engine ceased operation. The pilot then initiated a forced landing towards a nearby clearing.
Pilot Actions
The pilot stated that he had no prior experience landing with a feathered propeller. In his attempt to land in the clearing, the aircraft floated across the intended landing area and struck trees at the far end. The impact resulted in substantial damage to the aircraft.
Examination Findings
Post-accident examination of the engine revealed a separation through the flange of the oil jet. The fracture features were consistent with high cycle fatigue, with crack initiation occurring at multiple points along the flange surface. No tool marks were observed in the vicinity of the fracture. The material of the oil jet flange was identified as the specified aluminum alloy, with no anomalies noted in its composition.