Beech P35 N9532Y accident near Wichita Falls, Texas

Probable cause

The loss of engine power due to the misrigging of the fuel mixture control.

NTSB analysis

The pilot reported that, while turning from the downwind to the base leg to prepare for a short-field landing on the runway, he reduced the throttle. He then applied throttle to increase the power when the airplane was about 600 feet above ground level; however, the engine did not respond, and the pilot subsequently executed a forced landing to a field. During the landing, both wings sustained substantial damage.

During an engine test run with the cockpit fuel mixture control in the full-forward position, the engine would lose power when the throttle was advanced past 2,000 rpm. When the cockpit fuel mixture control was pulled out about 1 inch, the engine would develop 2,700 rpm (full power) when the throttle was advanced. The examination of the engine revealed that the lean mixture stop pin in the fuel metering unit was loose and could be removed by hand. Wear was observed on the inside of the fuel mixture actuating arm and on the mixture stop on the rotating shaft. The fuel metering unit's rich mixture stop pin was missing, which allowed the actuating arm to travel past the full-rich mixture position. A bench test of the fuel mixture control demonstrated that extension past the rich mixture stop pin reduced the fuel flow to the engine. This condition indicates that the airplane's fuel mixture control was misrigged, which resulted in the rich mixture stop pin dislodging from the fuel metering unit. It could not be determined when the fuel mixture control was misrigged.

Text from the NTSB. Open the NTSB docket for CEN14LA165 for the full record.