Ayres S2R-G6 N60015 accident near Ainsworth, Iowa

Probable cause

A component failure of the fuel control unit, which resulted in a loss of engine power.

NTSB analysis

The airplane experienced a loss of engine power while maneuvering at a low altitude during an aerial application flight. The pilot was unable to regain engine power after he turned the boost pump on and moved the throttle control to the full forward position. He then performed a forced landing on terraced terrain. A postaccident engine examination revealed evidence of continued rotation when the airplane impacted the ground. Examination of the fuel control unit (FCU) revealed that the bellows spring was fractured and the overspeed governor ball head bearing retainer was fragmented. Pieces of the fragmented retainer were found within the flow divider and fuel manifold. An unidentified contaminant was observed on the bearing race shoulder which misaligned the ball head bearing. The FCU was reportedly overhauled in 2003, but there were no component or aircraft records indicating the FCU's maintenance and installation since its manufacture. A search of the Federal Aviation Administration's service difficulty database did not specifically cite failures of the ball head bearing retainer, and the failures that were listed did not indicate the nature of those failures. The FCU manufacturer reported having no record of failures of the ball head bearing retainer; however, the repair facility that overhauled the FCU reported they had seen failures of the ball head bearing retainer.

Text from the NTSB. Open the NTSB docket for CEN09LA403 for the full record.