Originally Posted by
Maxmotor
The door is spring loaded along with a snubber and counter balance actuator.
Interesting, thanks! Does that make it easier to close and reset the mechanism if the door is opened without need, or for access to the wing surface?
Originally Posted by
NSEU
Just to clarify, fuselage skin part of the door rotates outwards/upwards. Only the slide assembly falls outside (like the main cabin doors).
The 747-400 upper deck door security relies on large pins sitting in L shaped-slots (plus the electronic system locking the door handle in flight). The locking system can be inoperative for flight as long as the door is guarded by the flight attendant when cabin/external differential pressures are low. With larger differential pressures, the door latching mechanism is loaded up with greater mechanical forces (making it impossible to open the door).
Is this design common to a lot of doors? Certainly A320-series main doors I've seen seem similar, the door moves inwards then down to align pins in slots as you describe. Therefore it's an outward opening door with most of the inherent safety benefits of a plug door.