What was found
DURING CRUISE, COULD NOT CLOSE NR 1 PYLON VALVE WITH ASSOCIATED SWITCH, VLV CLOSED. ON ENG SHUT DOWN (DIV). DURING CRUISE, COULD NOT CLOSE NR 3 PYLON VALVE WITH ASSOCIATED SWITCH, VLV CLOSED. ON ENG SHUT DOWN (DIV). DURING CRUISE, COULD NOT CLOSE NR 4 PYLON VALVE WITH ASSOCIATED SWITCH, VLV CLOSED. ON ENG SHUT DOWN (DIV). RAN NR 1 ENGINE & CHECKED OPERATION OF NR 1 PYLON VALVE GROUND CHECK OK PER 36-11-04. RAN NR 3 ENGINE & CHECKED OPERATION OF NR 3 PYLON VALVE GROUND CHECK OK PER 36-11-04. REMOVED AND REPLACED NR 4 PYLON VLV AS PER MM 36-11-04, OPS CHECK NORMAL.