Narrative:

At the end of the boarding process; purser asked us (the cockpit crew) for help because she was having difficulties closing the main cabin door (L1). As captain was getting ready to leave the cockpit in order to assist the flight attendants; purser informed us the door was closed and gave us a verbal 'cabin ready.' the cockpit overhead main cabin door light was extinguished; indicating the door was in fact closed and locked. During the climb out; at around 1500 ft; purser called the cockpit to inform us that there was a loud and abnormal 'air vacuum' like noise coming from the main cabin door (L1). During my conversation with the purser; the 'air vacuum' noise was loud enough to come through the intercom system. At that point I asked the purser to stay calm and that we would get back to her. As the airplane continued to climb; the noise was loud enough so it was heard in the cockpit. We also noticed an excessive cabin rate of climb (2000+ FPM); and very little cabin pressure differential. Captain and I came to the conclusion that the airplane was not pressurizing properly; we leveled off at 5000 ft and asked to return back to our departure airport. No emergency was declared and both the approach and landing were uneventful. Upon our return to the ramp; the ramp crew informed us that prior to our taxi for departure; while on the ramp; even though the main cabin door was closed; it did not look aligned with the fuselage as it normally does. We called maintenance control and a contract mechanic was sent out to the airplane to inspect the L1 door. While on the ground; under the supervision of the mechanic; the door was inspected and the airplane was pressurized. The door and it seals sustained no damage and the pressurization system worked properly. We completed our flight and we had no further incidents.

Google
 

Original NASA ASRS Text

Title: A B737-800 First Officer reported the Flight Attendant had difficulty closing main entry door (L1) and the aircraft subsequently failed to pressurize after takeoff. They returned to departure airport and the door was closed by maintenance with no further issues.

Narrative: At the end of the boarding process; Purser asked us (the cockpit crew) for help because she was having difficulties closing the main cabin door (L1). As Captain was getting ready to leave the cockpit in order to assist the flight attendants; Purser informed us the door was closed and gave us a verbal 'cabin ready.' The cockpit overhead main cabin door light was extinguished; indicating the door was in fact closed and locked. During the climb out; at around 1500 FT; Purser called the cockpit to inform us that there was a loud and abnormal 'air vacuum' like noise coming from the main cabin door (L1). During my conversation with the Purser; the 'air vacuum' noise was loud enough to come through the intercom system. At that point I asked the Purser to stay calm and that we would get back to her. As the airplane continued to climb; the noise was loud enough so it was heard in the cockpit. We also noticed an excessive cabin rate of climb (2000+ FPM); and very little cabin pressure differential. Captain and I came to the conclusion that the airplane was not pressurizing properly; we leveled off at 5000 FT and asked to return back to our departure airport. No emergency was declared and both the approach and landing were uneventful. Upon our return to the ramp; the ramp crew informed us that prior to our taxi for departure; while on the ramp; even though the main cabin door was closed; it did not look aligned with the fuselage as it normally does. We called Maintenance Control and a contract Mechanic was sent out to the airplane to inspect the L1 door. While on the ground; under the supervision of the Mechanic; the door was inspected and the airplane was pressurized. The door and it seals sustained no damage and the pressurization system worked properly. We completed our flight and we had no further incidents.

Data retrieved from NASA's ASRS site as of April 2012 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.