Event Summary
A pilot switched both fuel selectors from the auxiliary tanks to the main fuel tanks and initiated a descent by reducing power. During the descent, the right engine lost power, followed shortly by the left engine. The pilot performed the emergency checklist and successfully restarted both engines. Subsequently, the right engine again lost power.
During the subsequent single-engine landing, the landing gear collapsed, and the airplane exited the runway.
Pilot Statement
The pilot stated that the "fuel selector valve failed to seal poppet valves internally, resulting in no fuel to right engine." Additionally, the pilot noted that the "landing gear did not fully deploy on approach."
Landing Gear Examination
Impact damage to the main landing gear assembly precluded a determination of the reason for the collapse of the landing gear. However, the motor operated when power was applied.
Fuel Selector Valve Findings
During disassembly of the right fuel selector valve, the three Rulon-A seals were found depressed (stuck in the downed position) level with the housing, and the spring follower bushings for all three seals were missing.
The fuel selector valve was re-assembled and pressure tested in accordance with manufacturer specifications. When the valve was set in the off position, leakage from the main port to the engine port was 212.904 cubic centimeters (cc) (specification 0.5 cc with 40 psig). When the valve was set in the main position, leakage from the auxiliary port to the engine port was 319.3456 cc (specification 0.5 cc with 8 psig).
However, according to the manufacturer's representative, with the "right engine fuel selector valve in the right main tank position, the leakage would not prevent the right engine from operating when the fuel boost pumps were in the on position."