Cessna 172 N7033Q accident near Placerville, California

Probable cause

The partial loss of engine power due to an improperly maintained carburetor.

NTSB analysis

During the climb after takeoff the engine lost partial power. The pilot performed troubleshooting steps and initiated a return to the airport. The airplane was not able to maintain altitude and landed in trees about 300 ft short of the approach end of the runway.

Postaccident examination revealed sooting signatures on the spark plug electrodes and inner surfaces of the exhaust pipe, indicating an excessively rich fuel-to-air mixture. Examination of the carburetor revealed multiple maintenance-related discrepancies, including an incorrectly adjusted float and a loose carburetor bowl. The discrepancies likely resulted in mixture irregularities and a loss of engine power.

Maintenance instructions and a series of service bulletins had been published by the carburetor manufacturer to address these issues. The discrepancies appeared to have been present for a while and were likely present at the time of the last annual inspection. The carburetor had not been overhauled or serviced in at least 19 years even though the manufacturer recommended overhaul at 10-year intervals.

Text from the NTSB. Open the NTSB docket for WPR19LA102 for the full record.