What was found
CREW REPORTED NR 1 ENGINE OIL LOSS INFLIGHT. NR 1 ENGINE SHUT DOWN. RETURN TO FIELD. AFTER ARRIVAL AT GATE INSPECTED NR 1 ENGINE. OPENED OUTBOARD COWL. COWL RETENTION BAR WAS NOT IN THE SECURE POSITION. OIL CAP WAS SECURE. FOUND CENTER MCD DISLODGED AND LOOSE IN THE IAW AMM 79-21-01 PPE AND TOMC REQUEST TO REMOVE AND REPLACE ENG 1 LUBE UNIT NR 1 ENGINE REPLACED PER ETASK CARDS. ROTABLE PARTS CHANGE WAS INDICATED - TT 1024040 SN OFF 4866 ENGINE, BASIC, OFF 58-7200-9-0005 4866 ON 58-7200-9-0005 6195 INSPECTED PER GMM 09-25-05.