What was found
THUMPING NOISE AT DOOR 1R INFLIGHT. DURING A DETAILED VISUAL INSPECTION OF R1 DOOR, FOUND LOWER DOOR BUSTLE DETACHED & LOOSE ON FWD SIDE. BUSTLE RESECURED IAW AMM 25-66-01-416-010. WHILE CARRING OUT THE EXCESSIVE CABIN PRESSURE LEAKAGE TEST IAW AMM 05-51-24-782-001, ACFT FAILED TO MAINTAIN PRESSURE. OBSERVED THAT LOWER POSITIVE PRESSURE RELIEF VALVE HAD OPENED & WAS VENTING OVERBOARD. CABIN PRESSURE LEAK CHECK CARRIED OUT, POST POSITIVE PRESSURE RELIEF VALVE REPLACEMENT, IAW AMM 05-51-24-782-001. LEAK CHECK PASSED. OBSERVED PRESSURE DROP FELL WITHIN SATIAFACTORY ZONE LIMITS. NO AUDIBLE NOISES OR LEAKS NOTICED INTERNALLY OR EXTERNALLY AT R1 DOOR OR AROUND ACFT. LOWER POSITIVE PRESSURE. RELIEF VALVE REPLACED IAW AMM 21-32-01/201. STATIC SYS LEAK CHK OF LOWER POSITIVE PRESSURE RELIEF VALVE TO BE CARRIED OUT.