What was found
(CAN) TWO AIR TURN BACK DUE TO A #1 START VALVE OPEN LIGHT ILLUMINATED DURING FLIGHT. ACCOMPLISHED #1 ENGINE FAILURE SHUTDOWN TWICE.AFTER THE FIRST INCIDENT, THE STARTER, START VALVE AND ACTUATOR PRESSURE SWITCH WERE CHANGED, & THE SECOND TIME THE START VALVE & THE PRESSURE SWITCH WAS REPLACED. IT WAS DETERMINED THAT THE FIRST START VALVE WAS A ROGUE UNIT. THE FINAL FIX WAS THE REPLACEMENT OF THE STARTER VALVE.