What was found
ATB: CAB PRES ECAM AND RED MASTER WARNING LIGHT APPEARED CLIMBING THROUGH FL380. CABIN ALTITUDE WAS 10000 AND CLIMBING WITH BOTH OUTFLOW VALVES CLOSED. DESCENDED TO 10000. // FOUND AFT CARGO DOOR SEAL HAD A CUT ON THE OUTSIDE. UPON PRESSURIZATION, REVEALED AIR LEAK. REMOVED & REPLACED AFT CARGO DOOR SEAL REF A330 AMM 52-32-18. WORK IN PROGRESS. PERFORMED PRESSURIZATION RETEST AND LEAKAGE RATE MEASUREMENT PER A330 AMM 05-53-00. NO LEAKS NOTED ON AFT CARGO DOOR SEAL. TEST PERFORMED THREE TIMES. ALL OK. LEAKAGE RATE ALL WITHIN LIMITS. ALSO OPENED AND CLOSED CARGO DOOR MULTIPLE TIMES BETWEEN EACH PRESSURIZATION TEST. NO DEFECTS NOTED. MC NOTIFIED. OK FOR SERVICE. ALSO PERFORMED CPC SYS TEST PER A330 AMM 21-31-00. TEST OK.