What was found
DESCENDING THROUGH 16000' THE FLIGHT LEADER REPORTED MAIN CABIN DOOR MADE A LOUD POPPING SOUND AND THEN CONTINUED TO MAKE A RATTLING SOUND. GATE AGENT REPORTED ON ARRIVAL THE OUTSIDE MAIN CABIN DOOR HANDLE WAS NOT STOWED. FOUND EXTERNAL DOOR HANDLE SPRING BROKEN. REMOVED L1 SLIDE & PINNED. REF B737 AMM 25-66. REMOVED L1 DOOR LINER REF B737 AMM 52-11. REPLACED BROKEN SPRING REF CMM 52-16-12. INSTALLED DOOR LINER REF B737 AMM 52-11. INSTALLED L1 DOOR SLIDE PER B737 AMM 25-66. INSTALL OF L-1 SLIDE COMPLETE. RII C/W. (LOG 8352396 - AIRCRAFT WAS GROUNDED)