Cessna 172G N3682L accident near Reading, Michigan

Probable cause

The partial loss of engine power due to the improper securing of the throttle linkage by maintenance personnel.

NTSB analysis

The pilot reported that, while in cruise flight, the engine speed decreased from the selected cruise power setting to 1,900 rpm over a few seconds. The pilot was unable to restore full engine power; therefore, he performed an off-airport landing to a nearby field. The airplane abruptly stopped when it encountered an area of deep mud. A postaccident examination revealed that the throttle control had separated from the carburetor's throttle arm. The corresponding retention hardware was not recovered. The airplane had undergone an annual/100-hour inspection 2 days before the accident flight. The aviation mechanic who performed the inspection and held an inspection authorization certificate reported that, after completing the overhaul of the engine, he could not locate the specified cotter pin used to safety the airframe throttle control to the carburetor throttle arm; therefore, he chose to use safety wire to secure the throttle control assembly instead of the specified cotter pin. Therefore, the throttle control was not properly secured to the carburetor's throttle arm, which allowed them to separate during the accident flight.

Text from the NTSB. Open the NTSB docket for CEN13LA232 for the full record.