Amateur/Home Built/Experimental
Flight Crew Air Transport Pilot (ATP); Flight Crew Multiengine; Flight Crew Instrument
Confusion
Aircraft Equipment Problem Critical; Inflight Event / Encounter Fuel Issue
Flight Crew Landed in Emergency Condition
Aircraft; Human Factors
The airplane I am flying is an experimental type and is in phase one flight testing operating out of ZZZ. Returning to ZZZ after an hour personal flight. Wing tanks selected to BOTH feeding the engine. The right fuel tank would always drain more quickly than the left tank when the fuel selector is selected to BOTH. This is because the right tank has a little shorter routing then the left tank. Neither tank has a check valve in the fuel line so fuel does transfer back and forth during turns. Having done several takeoffs and landings at another airport with left hand pattern the right tank had been transferring fuel to the left hand tank in the turns since the fuel selector was on BOTH selection.On returning to land at ZZZ the engine quit due to sucking air from the right tank. I was high enough that a normal landing was made without further incident.I had assumed that by leaving the fuel selector in the BOTH position that the engine would draught fuel from the other tank if one was low. Wrong assumption.Check valves are being installed in the fuel tank lines to prevent cross ship transferring of fuel. Also; the POH is being changed to show tank to engine operation and not BOTH selection.
Experimental aircraft pilot reported the engine quit during approach due to it sucking air from the right fuel tank. Pilot was high enough on the approach to perform a normal glide landing.  Reportedly; the right tank transfers fuel to the left-hand tank when the fuel selector is on the 'BOTH' position causing the right tank to go low on fuel.