Beech 35-C33A N1259M accident near San Diego, California

Probable cause

A partial loss of engine power due to water contamination of the fuel system.

NTSB analysis

The pilot reported that, while approaching the destination airport at the conclusion of a cross-country flight with the fuel selector set to the fullest tank, the engine began to run rough and lost partial power. Unable to reach the runway, the airplane landed hard short of the runway, resulting in substantial damage.

A postaccident examination revealed no evidence of mechanical malfunction or failure. Fuel system continuity was confirmed, and a test run of the engine revealed no anomalies. The fuel strainer screen was removed and exhibited areas of corrosion.

A water-detecting paste revealed the presence of water in the fuel. The fuel manifold was disassembled. The rubber diaphragm inside was brittle and exhibited peeling, and there were numerous rubber flakes found, but it could not be determined if the contaminants would have affected the operation of the unit. There was evidence of rust on the screen and in the cavity. The fuel strainer screen and the fuel cap (filler) receptacles also contained rust consistent with water in the fuel system. Although the investigation was unable to determine when the water was introduced into the fuel system, the presence of rust was consistent with long-term water exposure.

Given the successful engine test run and the lack of anomalies of the fuel system, and the corrosion observed on some fuel system components, it is likely that the loss of engine power was the result of water contamination of the fuel system.

Text from the NTSB. Open the NTSB docket for WPR24LA174 for the full record.