Piper PA-22-135 N3431A accident near Bangor, Michigan

Probable cause

The pilot’s failure to properly service the fuel system, and subsequent decision to conduct the flight with known fuel system deficiencies, which led to the total loss of engine power.

NTSB analysis

On the day before the accident, the owner/pilot made a forced landing to a field due to a loss of engine power. No damage was incurred during that event. Examination of the airplane after the off-airport landing revealed that the gascolator screen was almost completely plugged by a flaky, shellac-type material. The airplane had a history of automotive fuel use, and the inspector who examined the airplane told the pilot that he should have a local mechanic do a thorough fuel system evaluation and flushing before further flight. He reminded the pilot that there were screens in the fuel tanks, carburetor, and in the belly sump that should be checked and cleaned. On the day of the accident flight, the pilot and a local mechanic added fuel to the right fuel tank and performed fuel flow tests. The pilot then attempted to take off, and the engine stopped producing power. The airplane impacted the ground in a left turn and nosed over. Examination of the airplane after the accident revealed that the carburetor and gascolator screens were 50 percent obstructed. Neither the pilot nor the mechanic indicated in their postaccident statements that the gascolator, carburetor, or fuel tank screens were checked or that the fuel system was flushed to remove the residual fuel system contaminants. Based on the available evidence, it is likely that the engine power loss was due to the obstruction of the fuel system screens, which prevented adequate fuel flow to the engine.

Text from the NTSB. Open the NTSB docket for CEN12LA348 for the full record.