What was found
PDIS 585 52-30 0345 02FEB22 IUD OPEN U AIR TURN BACK AFTER TAKEOFF FROM OTBH. MAIN CARGO VENT DOOR OPEN, NO ALERTS. DUMPED APPROXIMATELY 58K BEFORE LANDING. INSPECT VENT DOOR. PART 02FEB22 04:51 MC1 U IDENTIFIED PARTS SWITCH 27/32/52 MPN: H20-24B CPN: 0030004 QTY: 1 MEL 02FEB22 05:01 IUD U RELEASED FOR SERVICE PER MEL : 52-40-01-06 CATEGORY : B EXPIRATION : 05FEB22 "MEL 52-40-01-06: CARGO DOOR UPR A ALERT - INOP. VERIFY DOOR IS CLOSED AND LOCKED PRIOR TOBLOCK-OUT." MAIN CARGO DOOR "A" INDICATION INOP C/7303873 FACT 03FEB22 11:38 MEM RESTORED AIRCRAFT TO NORMAL CONFIGURATION PER MEL 52-40-01-06 .REPLACED MAIN CARGO DOOR VENT PROX IMITY SWITCH PER AMM MD-11 AMM 52-70-00-5. PERFORMED OPERATIONAL TEST PER AMM 52-70-00-5. OPS CHECK GOOD.