What was found
L1 DOOR MADE CRACKING / BANGING NOISE FOR DURATION OF FLIGHT. DOOR WAS BULGING INWARD APPROX 1-2 FROM ABOUT HALFWAY UP AND FROM APPROX 6 FROM EITHER SIDE. GROUNDED. INSPECTED L1 DOOR REF AMM 52-11-00-206-001. FOUND LOWER FWD STOP PIN LOCK SPRING MISSING AND STOP PIN MIS-ADJUSTED. ADJUSTED STOP PIN AND INSTALLED LOCK SPRING REF AMM 52-11-00-705-007. ALSO FOUND UPPER DOOR LINER OUT OF POSITION. REMOVED AND CORRECTLY INSTALLED UPPER DOOR LINER REF AMM 52-11-31-404-009. DOOR OPS CKS GOOD REF AMM 52-11-00-755-051. PRESSURIZED ACFT AND DOOR OPS AND LEAK CKS GOOD REF AMM 05-51-91-702-001. NO NOISE HEARD FROM DOOR OR LINER.