What was found
CABIN PRESSURE MASTER WARNING ILLUMINATED AT FL220. DIVERTED AND ACCOMPLISHED UNEVENTFUL LANDING. AIRCRAFT REMOVED FROM SERVICE. INSPECTED THE DOOR SEALS AND FOUND AFT CARGO DOOR SEAL DISBONDED AT AFT UPPER CORNER AND NOTED TWO HOLES IN THE SEAL. REMOVED AFT CARGO DOOR SEAL IAW AMM 52-31-26-000-801, STEPS 1-4. INSTALLED NEW SEAL IAW AMM 52-31-26-400-801. FUNCTIONAL CHECKED GOOD. PRESSURIZED AIRCRAFT TO 5 DP. NO PRESSURE WARNING. RETURNED TO SERVICE.