What was found
FLT#2237, JFK- STI. (AIRCRAFT PERFORMED AN AIR TURN BACK TO JFK) ' AIR WING LEAK (L) AIR RETURN; REF L/P 3414696, ITEM#1 (FOUND TORN/MISSING SEAL ON DUCT Z521. REMOVED AND REPLACED SEAL AND MUFF INSULATION IAW AMM 36-11-05. OPS CHECK AND LEAK CHECK GOOD. NO FAULTS NOTED. A/C OK FOR CONTINUED SERVICE AT THIS TIME). A/C OK FOR CONTINUED SERVICE.'