As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
FLT#BOS-CLT. AIRCRAFT PERFORMED AND AIR TURN BACK TO BOS. THROUGH 8000 CARGO DOOR INDICATION APPEARED. AUDIBLE THUMPING NOISE ASSOCIATED. ADJUSTED VENT FLAP MECHANISM IN FWD CARGO DOOR AND EXTERNAL HANDLE IAW AMP 52-30-16-01AAA-271A-A. CARGO DOOR OPS TEST GOOD IAW AMP 52-30-00. CARGO DOOR PROX SENSOR OPS TEST GOOD. NO FAULTS IAW AMP 52-73-01.