What was found
FA'S REPORTED AFTER TAKEOFF LOUD AIR NOISE FROM L-1 DOOR. PILOTS CONFIRMED L-1 ENTRY DOOR LT WAS EXTINGUISHED. ALSO CONFIRMED A/C WAS NOT PRESSURIZING. GROUNDED - YES. AIR TURNBACK - DIVERSION TIME 16 MINUTES. FOUND LOWER INTERIOR HINGE COVER SNUBBER CREATES A ROUGHLY 1" GAP. REMOVED L-1 DOOR LOWER HINGE FLAPPER SEAL REF AMM 52-11-00-020-801, INSTALLED NEW L-1 DOOR LOWER HINGE FLAPPER SEAL REF AMM 52-11-00-420-801 ACCOMPLISHED CABIN PRESSURE LEAK TEST. OPS CHECKED OK. NO NOISE COMING FROM L-1 DOOR. REF AMM 05-51-91-790-801.