What was found
ON CLIMBOUT AT FL230 AND 310 KTS MAIN CARGO DOOR-B ILLUMINATED. DECLARED EMERGENCY AND RTB. LIGHT WENT OUT DESCENDING THRU FL180 AND 250 KTS, MEL 09APR05. RELEASED FOR SERVICE PER MEL/CDL: 52-15-01 CATEGORY: C EXPIRATION: 19APR05 B-LOOP MEL'D REF MEL 52-15-01: MAIN CARGO DOOR WARNING LIGHT SYS B-INOP. VERIFY DOOR CLOSED AND LOCKED PRIOR TO EACH BLOCKOUT. CYCLED DOOR & VERIFED CLOSED AND LOCKED. ADJUSTED B-SWITCH AFT CABLE ASSY PER NASI MM 52-30-00. OPS CKS NORMAL.