What was found
CABIN BEGAN DEPRESSURIZING AT APPROX 14,000' WHILE TO 17,000' . LOUD AIR SOUND LT SIDE OF ACFT DURING DEPRESSURIZATION. AMBER FOLLOWED BE RED CABIN ALT CAS. SHORTLY AFTER AMBER CHECK DOORS & MAIN CABIN DOOR CAS. AFTER LANDING, INSPECTED DOOR PINS & HANDLE POSITION.6 PINS SHOWED LOCKED & HANDLE DOWN & SECURE. RAN DOOR RESET CHECKLIST OUT OF QRH TO CLEAR DOOR FAULTS. CONNECTED MLG SIMULATOR BOX & PERFORMED PRESSURIZATION OF ACFT WITH APU. WHILE OUTSIDE OF ACFT, NOTED THE BAGGAGE DOOR HAD A MASSIVE LEAK. TECHS INSIDE ALSO NOTED LEAK & FOUND PULL DOWN ASSIST STRAP TO BE WEDGED INTO CARGO DOOR. HAD TO DEPRESSURIZE ACFT TO REMOVE STRAP. REPRESSURIZED ACFT WITH NO FAULTS. WORK DONE IAW AMM 21-30-00.