AN L1011-500 RETURNED TO THE FIELD DUE TO THE CREW RPTING A THUMPING SOUND INFLT. FOUND CARGO DOOR ACCESS PANEL DEPARTED THE ACFT. CAUSED BY ACCESS PANEL LATCH FAILURE.

Narrative

ACFT ARRIVED AS A FERRY FLT FROM ZZZ. THE BAG LOADERS NOTIFIED ME THAT THE C-2 CARGO DOOR WOULD NOT OPEN ELECTRICALLY. I NOTICED THAT NONE OF THE CARGO DOORS HAD PWR TO THEM. I THEN PROCEEDED TO PREPARE TO MANUALLY OPEN THE C-2 DOOR IF NEED BE BY OPENING THE FAIRING ACCESS PANEL; WHICH IS CLOSED BY 4 LATCHES. I THEN REALIZED THAT THE NOSE GEAR STRUT LOOKED OVER EXTENDED. I ASKED THE RAMPERS TO HOOK A TUG AND TOW BAR UP. THIS HELPS BRING THE STRUT DOWN SOMETIMES. THIS WORKED AS FOR THE SQUAT SWITCH ENGAGED AND THE CARGO DOOR PWR WAS BACK. I PROCEEDED TO CLOSE THE ACCESS DOOR THAT WAS OPENED AND VERIFIED THAT THE LATCHES WERE ENGAGED. I THEN PROCEEDED TO DO A TIRE CHANGE. WE HAD 15 MINS BEFORE DEP. I MADE A FINAL WALKAROUND OF THE ACFT AND THE PANEL WAS CLOSED. OUR RAMPERS ALSO MAKE A FINAL WALKAROUND -- THIS IS A NORMAL PROC. THE ACFT TOOK OFF AND APPROX 30 MINS INFLT; THE FLT CREW RPTED A THUMPING SOUND FOR ABOUT 10 MINS AND DECIDED TO COME BACK TO THE ARPT. UPON ACFT ARR I NOTICED THE C-2 DOOR FAIRING ACCESS DOOR MISSING. UPON FURTHER INSPECTION; I FOUND THAT THE DOOR WAS LATCHED UPON DEP DUE TO THE METAL DAMAGE ON THE LIP. THIS WAS IN LINE WITH THE DOOR LATCHES PULLING ON THE METAL LIP. THE ACFT WAS INSPECTED FOR ANY FURTHER DAMAGE; BODY; TAIL AND ENGS. THE L1011 CDL MANUAL PAGE 35.1 CDL #53-52 DOES NOT REQUIRE THIS DOOR TO BE INSTALLED FOR CONTINUED FLT. I CDL'ED THE ITEM AND RELEASED THE ACFT FOR FLT. I HAVE SEEN THIS DOOR MISSING 3 TIMES BEFORE IN ABOUT 10 YRS. I CONTRIBUTE THIS ITEM TO A LATCH FAILURE. IF THIS PANEL IS SUBJECT TO DEPART THE ACFT; I THINK A BETTER DESIGN WOULD HAVE BEEN 2 LATCHES IN THE AIRSTREAM INSTEAD OF JUST 1. THIS PANEL HAS 1 LATCH IN THE AIRSTREAM; 2 ON THE BOTTOM; AND 1 ON THE AFT EDGE.