What was found
AIRCRAFT WAS GROUNDED: PASSING 12000, A LOUD SQUEAL INDICATING A PRESSURIZATION LEAK WAS NOTED. PILOTS DECIDED TO RETURN TO MIA, FLIGHT LANDED OVERWEIGHT WITHOU INCIDENT. MAINTENANCE DETRMINED THAT THE R1 DOOR GIRT BAR SKIRT WAS STUCKUNDER THE DOOR SEAL. ADJUSTED GIRT BAR SKIRT IAW AMM 25-66-01. PRESSURIZED AIRCRAFT TO 4.O PSI DIFFERANTIAL PRESURE IAW AMM 05-51-24. NO LEAKS NOTED.