Originally Posted by YRP
Is this really true that the 747 upper deck and 737-800/900 have non-plug type emergency exit doors?
That seems surprising. Plug type is such a nice engineering solution: open-able exactly when you want it to be, not when you don't.
Originally Posted by triploss
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).