What was found
NR 1 ENG LOST OIL QTY 1 GAL, 1/2 HR SHUT ENG DOWN AT 0930Z WITH 1.25GAL REMAINING. PERFORMED WINDMILLING ENG PROCEDURE AT 1000, 1030, 1050Z. WINDMILLING OP 19 PSI TEMP 50 DEGREE C 1000Z QTY .5 GAL QTY IND 0 GAL AT 1025Z OP 21 PSI TEMP 40 DEGREE. OP ONLY WENT TO ZERO AFTER A/C ON LANDING ROLL. INSPECTED NR 1 ENG FOUND GEARBOX DRIVESHAFT HOUSING LEAKING AT ANGLE GEARBOX. R/R`D D/S HOUSING O-RINGS IAW P&W E.M 72-00-67. PERFORMED ENG WINDMILL INSPECTION IAW B747 MM 72-00-00. REMOVED OIL FILTER AND FOUND FREE OF DEBRIS. INSTALLED NEW OIL FILTER IAW B747 MM 72-61-05. REMOVED CHIP DEL FOUND FREE OF DEBRIS AND REINSTALLED IAW 72-61-00. SERVICED OIL SYS AND IDLE RAN ENG FOR LEAKS. LEAK CHECKS GOOD.