5 ms·

I don't understand why the plug doesn't use pressure as a failsafe. You have high pressure one side, low the other side, and just like normal airline doors the

I don't understand why the plug doesn't use pressure as a failsafe. You have high pressure one side, low the other side, and just like normal airline doors the interior pressure makes it impossible to open the door.

g-b-r 3y ago
You'd probably still need bolt somewhere... (rivets actually?)
mips_r4300i 3y ago
That is exactly how it works actually. There are a series of ears around the door, and the pressurization of the cabin forces the door out and against the airplane frame mating ears. The more it pressurizes, the greater the force jamming the door shut. However, since it's a door, it has to be able to open. The door is constructed such that if you slide it upwards, the ears clear each other and the door can come out. There are bolts to physically block the door plug from ever sliding upwards. If the bolts were correctly installed, or ever installed at all, the door would be perfectly safe.
- monkeynotes 3y ago
  I understand the vulnerability of the slide up thing, but I guess what I didn't explain properly is why doesn't it open by swinging inside instead of upwards? I don't know if I've ever seen a passenger door that slides up, but I haven't flown on all aircraft types.
  - cameldrv 3y ago
    Adding a hinge there would be extra weight, but probably more importantly, the plug door is convertible to an emergency exit, so you want the hardware to be similar to the emergency exit door. For those, the door comes completely off and you throw it out of the plane when you use it. If the door hinged inward, it would take up a lot of space in the cabin during an evacuation and slow down people trying to get out. Ultimately it's extremely difficult to make a plane where you can just not install a bunch of bolts and everything still keeps working fine. You have to have a high quality manufacturing operation to make a reliable plane.
  - hedgehog 3y ago
    Emergency exit doors should open outward, fall outward, etc, otherwise people rushing to get out could pile up and get stuck. True in buildings as well as vehicles. Some Airbus models have a similar upward hinge on at least some exits, I think on many the door fully detaches and you're supposed to chuck it out of the way.

g-b-r 3y ago

You'd probably still need bolt somewhere... (rivets actually?)

mips_r4300i 3y ago

That is exactly how it works actually. There are a series of ears around the door, and the pressurization of the cabin forces the door out and against the airplane frame mating ears. The more it pressurizes, the greater the force jamming the door shut. However, since it's a door, it has to be able to open. The door is constructed such that if you slide it upwards, the ears clear each other and the door can come out. There are bolts to physically block the door plug from ever sliding upwards. If the bolts were correctly installed, or ever installed at all, the door would be perfectly safe.

monkeynotes 3y ago
I understand the vulnerability of the slide up thing, but I guess what I didn't explain properly is why doesn't it open by swinging inside instead of upwards? I don't know if I've ever seen a passenger door that slides up, but I haven't flown on all aircraft types.
- cameldrv 3y ago
  Adding a hinge there would be extra weight, but probably more importantly, the plug door is convertible to an emergency exit, so you want the hardware to be similar to the emergency exit door. For those, the door comes completely off and you throw it out of the plane when you use it. If the door hinged inward, it would take up a lot of space in the cabin during an evacuation and slow down people trying to get out. Ultimately it's extremely difficult to make a plane where you can just not install a bunch of bolts and everything still keeps working fine. You have to have a high quality manufacturing operation to make a reliable plane.
- hedgehog 3y ago
  Emergency exit doors should open outward, fall outward, etc, otherwise people rushing to get out could pile up and get stuck. True in buildings as well as vehicles. Some Airbus models have a similar upward hinge on at least some exits, I think on many the door fully detaches and you're supposed to chuck it out of the way.