737 Overwing Exits
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737 Overwing Exits
The latest 737's (800's at least) have power operated over-wing exits. The exit/window hinges at the top and stays attached to the airframe. Can anyone explain the rationale behind exits over the plug and throw away variety? They must have a fully independent power source, presumably hydraulic. How is this achieved? Any MM/IPC drawings to post? What other aircraft type(s) use these exits?
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They told me on my Level III course that Boeing first planned to leave the overwing exits on the 737NG as they are on
the 737CL. But FAA wanted that the door can be opened more quickly. Also it has to stay out of the evacuation way.
Now the overwing exit is hinged at the upper side and after unlocking of the door swings outside forced by an
counterbalance assembly.
But I think that Pictures are better than words:
Detailed view
Operation
View in open position
HIH
Ingo
the 737CL. But FAA wanted that the door can be opened more quickly. Also it has to stay out of the evacuation way.
Now the overwing exit is hinged at the upper side and after unlocking of the door swings outside forced by an
counterbalance assembly.
But I think that Pictures are better than words:
Detailed view
Operation
View in open position
HIH
Ingo
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If l remember the FAA were happy with the exit, but it was JAA that said no and mandated it as it is today. I think the first few NG 737s had the old exit at build and were modified later.
UkEng
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Never worked on this type but it's good to see - Airbus could take a leaf out of their book and do something similar.
Anyone who's removed one of the plug doors for maintenance will agree they're a liability - I shudder to think what kind of chaos they cause in a real emergency as they aren't light and the natural thing to do is drop it in the cabin and climb over it.
Hard to believe doors this small are still used
Anyone who's removed one of the plug doors for maintenance will agree they're a liability - I shudder to think what kind of chaos they cause in a real emergency as they aren't light and the natural thing to do is drop it in the cabin and climb over it.
Hard to believe doors this small are still used
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Mr @ Spotty M wrote
I can confirm Mr @ Spotty M predication about the first 737NG overwing exits, but i´m realy not sure who strongly
request the designchange.
@ ukeng
But the NG now produces false Warnings from the Flight lock mechanism.
Ingo
l remember the FAA were happy with the exit, but it was JAA that said no and mandated it as it is today. I think the first few NG 737s had the old exit at build and were modified later.
request the designchange.
@ ukeng
But the NG now produces false Warnings from the Flight lock mechanism.
Ingo
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Now that we've got some drawings I can see the sense behind these exits. If JAA insisted on them then why hasn't Airbus started using the idea? How do the 'counterbalance' units work. Springs, gas units?
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@ forget
I have in mind that the counterbalance contains 2 very strong Springs. 
Ther are no further detailed information in my Training Manual.
I´ll try to find more Information in the AMM.
Ingo
...How do the 'counterbalance' units work. Springs, gas units?
Ther are no further detailed information in my Training Manual.
I´ll try to find more Information in the AMM.
Ingo
