What was found
FLT # 172, FLL-LGA (AIR TURNBACK TO FLL). R1 DOOR LOUD HUMMING NOISE AND VIBRATION ABOVE FL100 AND VERY BAD ABOVE FL250 - FLOOR VIBRATING, SMOOTH LANDING, NORMAL @ LANDING NOT OVERWEIGHT; INSPECTED R1 DOOR IAW AMM 52-11-00. CONDITION OF DOOR SEALS AND DOOR OPERATION NORMAL. INSPECTED FWD FUSELAGE AVIONICS ACCESS DOORS AND AREAS IAW AMM 05-28-00 NO FAULT FOUND, PRESSURIZED A/C IAW AMM 05-53-00 ALL CHECKS NORMAL. PERFORMED INSPECTION FOR OVERWEIGHT LANDING IAW AMM 05-51-11. A/C OK FOR SERVICE.