B737-700
Flight Crew Air Transport Pilot (ATP)
Distraction; Situational Awareness
Aircraft Equipment Problem Critical
Flight Crew Returned To Departure Airport; General Maintenance Action; General Flight Cancelled / Delayed
Aircraft
When the L1 door was closed there was a 1' gap visible from the outside (found by maintenance upon return). From the inside the door appeared to be fully closed and all flight deck door lights were out. After takeoff the cabin wouldn't pressurize (all air switches were in the proper position). The Flight Attendant called out of 5;000 FT with a loud noise coming from L1 door. We were cleared to descend to 3;000 FT. All notifications were carried out and we returned to [the departure airport].
A B737-700 main cabin door's bottom segment did not close completely which created a loud noise at the door after takeoff and the cabin would not pressurize so the flight returned for maintenance.