Beech M35 N339Z accident near Lake Havasu City, Arizona

Probable cause

The pilot's incorrect positioning of the fuel tank selector valve during a tank switch, which resulted in fuel starvation and a loss of engine power. Contributing to the accident was the worn condition of the fuel selector valve handle position detents and markings.

NTSB analysis

The pilot was conducting a personal cross-country flight. The fuel selector was set to the left main fuel tank for takeoff and climbout. After reaching cruise altitude, he switched to the auxiliary tanks and later to the right main fuel tank. While in cruise flight, he also activated the two fuel pumps to transfer fuel from the tip tanks to the main tanks. When the airplane was about 4 miles from and 2,000 ft above the intended destination airport, the pilot switched to the left main fuel tank; the fuel-injected engine lost power, but the propeller continued to windmill. The pilot selected the landing gear down and attempted to restart the engine to no avail. The pilot determined that he would not make the runway and selected an open area as his landing target. He switched to the right main fuel tank, but the propeller continued only to windmill. The pilot then switched back to the left main tank and again could not start the engine. The airplane landed hard on flat desert terrain, which resulted in the nose landing gear collapsing and the fuselage buckling. The airplane slid upright to a stop.

On-site examination of the fuel tanks revealed that they were not breached; the left main fuel tank contained about 23 gallons of fuel, the right main tank contained about 20 gallons, and the auxiliary tanks and the tip tanks did not contain any fuel. Examination of the fuel system did not reveal any obvious reason for the engine power loss. Although the left main tank fuel pickup screen was found separated from its line, the line appeared clear and functional. The ports and chambers of the fuel selector valve were clear, and the valve was functional. The fuel selector valve handle position detents were worn so that proper selection of a fuel tank by tactile method alone was difficult or impossible, and the placard was worn to the point where the position marker for the left tank was absent. The engine was removed for examination and a test run, and there was no evidence of a mechanical anomaly that would have precluded normal operation.

Based on the pilot's reported sequence of events, the airplane examination, and the engine test run, it is likely that the pilot did not correctly position the fuel selector valve handle when he switched to the left tank for landing, which resulted in fuel flow interruption and power loss due to fuel starvation. The worn condition of the fuel selector valve made it susceptible to being mis-set, which would impede or terminate fuel flow to the engine. In addition, a fuel-injected engine can be more difficult and/or take longer to start after it is deprived of fuel. Due to the airplane's proximity to the ground, the pilot had limited time to troubleshoot or restart the engine.

Text from the NTSB. Open the NTSB docket for WPR17LA190 for the full record.