A B777 RETURNED TO FIELD WITH #1 ENG SHUTDOWN DUE TO LOSS OF OIL QUANTITY AND PRESSURE.

Narrative

I AND ANOTHER MECH WERE WORKING ON A CHANGE ORDER ON #1 ENG ON A B777. THIS CHANGE ORDER REPLACES THE MAIN OIL FILTER TUBE AND SCAVENGE OIL PUMP. IN THE PROCESS OF INSTALLATION; A DUST CAP WAS INADVERTENTLY LEFT INSTALLED AT THE FILTER HOUSING WHERE THE OIL TUBE CONNECTS. (THIS DUSTCAP IS A BAYONET TYPE AND IS NOT READILY VISIBLE.) WHILE THE ACFT WAS INFLT THE CAP MELTED; AND CAUSED AN INFLT SHUTDOWN DUE TO LOSS OF OIL AND PRESSURE. IN THE FUTURE; THIS MIGHT BE HIGHLY AVOIDABLE IF ALL THESE CAPS ARE REMOVED PRIOR TO ROUTING OF THE LINE DESPITE WHAT THE PROC RECOMMENDS. THE CAP WAS DISCOVERED AFTER THE ACFT RETURNED TO THE GATE AND THE OIL LINE WAS REMOVED FOR INSPECTION. PARTS OF THE MELTED CAP WERE FOUND IN THE MAIN OIL SCREEN. SUPPLEMENTAL INFO FROM ACN 345204: ON FIRST ENG RUN WE HAD SOME SMALL SEEPAGE AROUND MATING FLANGE. CHKED FLANGE AND HAD SOME GAP BTWN TUBE MATING FLANGE AND SEAL. RE-TORQUED BOLTS FOR TUBE CONNECTION AND DISCUSSED WITH ANOTHER MECH HOW GAP MIGHT BE CAUSED BY TUBE MATING ON CRUSH TYPE SEALING GASKET.