Aircraft Fuel Systems What method would be used to check for internal leakage of a fuel valve without removing the valve from the aircraft? a. Place the valve in the OFF position, drain the strainer bowl, and with boost pump on, watch to see if fuel flows to the strainer bowl. b. Remove fuel cap(s), turn boost pump(s) on, and watch for bubbling in the tanks. c. Apply regulated air pressure on the downstream side of the fuel pump and listen for air passing through the valve.