Narrative:

Passengers were boarded; and as second in command I gave them the standard safety briefing. After the safety briefing I closed and locked the cabin door. I proceeded to the flight deck to begin engine start and checklist duties as the pilot not flying. Engine start; taxi; and all associated checklists were completed uneventfully. There was a slight ATC delay for takeoff due to airport arrivals and departures on both runways at the airport. The departure for runway xx was assigned and thoroughly reviewed. After a 15 min. ATC delay we were cleared for takeoff on runway xx. Shortly after calling V1 and just before V2 I noticed the door seal and cabin door lights on the annunciator panel. Immediately after the aircraft became airborne and audible air leak was heard by everyone on the aircraft. The gear was retracted and I pointed out the illuminated annunciator to the pilot in command. At 400 feet the flaps were retracted. The pilot in command requested a call be made to tower to return for landing. I called tower with the request to return for landing for a maintenance issue. Tower responded to enter a right base for runway xx. Once on downwind I informed tower we were on a right downwind for runway xx. The pilot in command then requested that I inform the passengers of our intentions. I informed the passengers that we were returning for a minor mechanical issue and ensured that they were both seated and strapped in. The passengers acknowledged. The pilot in command selected flaps 15 while I was briefing the passengers. When I checked back in with the pilot in command he requested the short segment checklist. I performed the short segment checklist and boxed the landing speeds. As we were approaching abeam the numbers for runway xx; the door came completely open. I turned around to see some newspapers exiting the cabin door and the passengers still seated and strapped in. The pilot in command requested declaring an emergency which I did with tower. The gear was selected down. On base to final a GPWS warning was heard; acknowledged and I made call outs to the effect that we were slightly low but there was no imminent threat of a terrain incursion. Airspeed was around 150 and we were about 1 mile base to final so I suggested flaps 35 and the pilot in command called for flaps 35. The landing checklist was completed. Once on final I made a call to tower that we were on final to runway xx. Callouts were made for slightly low and on speed. The pilot in command's approach was smooth; consistent; and the landing was made on speed. We taxied clear of runway xx. The decision was made to shut down the aircraft just clear of runway xx on the taxiway. Since the cause is unknown; no suggestions can be made at this time.

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Original NASA ASRS Text

Title: A C560 crew reported that immediately after takeoff the main cabin door appeared to develop an air leak and a short time later came completely open. An emergency was declared and the aircraft returned to land.

Narrative: Passengers were boarded; and as second in command I gave them the standard safety briefing. After the safety briefing I closed and locked the cabin door. I proceeded to the flight deck to begin engine start and checklist duties as the pilot not flying. Engine start; taxi; and all associated checklists were completed uneventfully. There was a slight ATC delay for takeoff due to airport arrivals and departures on both runways at the airport. The departure for Runway XX was assigned and thoroughly reviewed. After a 15 min. ATC delay we were cleared for takeoff on Runway XX. Shortly after calling V1 and just before V2 I noticed the door seal and cabin door lights on the annunciator panel. Immediately after the aircraft became airborne and audible air leak was heard by everyone on the aircraft. The gear was retracted and I pointed out the illuminated annunciator to the pilot in command. At 400 feet the flaps were retracted. The pilot in command requested a call be made to Tower to return for landing. I called Tower with the request to return for landing for a maintenance issue. Tower responded to enter a right base for Runway XX. Once on downwind I informed Tower we were on a right downwind for Runway XX. The pilot in command then requested that I inform the passengers of our intentions. I informed the passengers that we were returning for a minor mechanical issue and ensured that they were both seated and strapped in. The passengers acknowledged. The pilot in command selected flaps 15 while I was briefing the passengers. When I checked back in with the pilot in command he requested the short segment checklist. I performed the short segment checklist and boxed the landing speeds. As we were approaching abeam the numbers for Runway XX; the door came completely open. I turned around to see some newspapers exiting the cabin door and the passengers still seated and strapped in. The pilot in command requested declaring an emergency which I did with Tower. The gear was selected down. On base to final a GPWS warning was heard; acknowledged and I made call outs to the effect that we were slightly low but there was no imminent threat of a terrain incursion. Airspeed was around 150 and we were about 1 mile base to final so I suggested flaps 35 and the pilot in command called for flaps 35. The landing checklist was completed. Once on final I made a call to Tower that we were on final to Runway XX. Callouts were made for slightly low and on speed. The pilot in command's approach was smooth; consistent; and the landing was made on speed. We taxied clear of Runway XX. The decision was made to shut down the aircraft just clear of Runway XX on the taxiway. Since the cause is unknown; no suggestions can be made at this time.

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.