What was found
RETURNED TO BLOCKS DUE TO ANTI ICE VALVE WARNING. THIS INCIDENT OCCURRED MOST LIKELY WHEN THE LT ENGINE ANTI-VALVE WAS DEFERRED INOPERATIVE PER THE MEL, AND, THE LT ENGINE ANTI-ICE VALVE SWITCH WAS LEFT IN THE INCORRECT POSITION AFTER REVIEWING THE MEL PROCEDURE, IT HAS BEEN FOUND THAT THE MEL WAS UNCLEAR WHAT POSITION THE VALVE SWITCH SHOULD BE IN WHEN THE VALVE WAS DEFERRED INOP. THIS STEP IS BEING CLARIFIED IN A REVISION TO THE MEL PROCEDURE.