Re: Boeing 777 Cabin Door

Date:         24 Mar 98 11:38:52 
From: (C. Marin Faure)
Organization: NorthWest Nexus Inc.
References:   1 2 3
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In article <airliners.1998.458@ohare.Chicago.COM>,
(David Lesher) wrote:

> (C. Marin Faure) writes:
> >The 777 uses a translating door. In other words, instead of retracting
> >into the cabin, pivoting, and then moving back out of the cabin like
> >earlier Boeing airplanes (except the 767 which uses a door that moves
> >straight up into the top of the cabin), the 777 door unplugs, moves
> >straight out, and then moves to the side.  The outside of the door always
> >faces out.  It is similar in operation to the door Airbus uses on some of
> >their models.
> But how does it DO that? I am picturing a tapered plug. Let's use
> the manhole ^H^H^H Maintenance Hatchway cover analogy. It can not
> fall into the hole since it is tapered. Is the 777 door also a
> tapered plug?  How than, does it 'fall through'...?

Maybe someone with direct experience with the 777 door design will answer
this.  But I do not believe the 777 door is a tapered plug.  If it was, it
wouldn't be able to move straight out as you point out.  I believe, and I
may be wrong, that the part of the door mechanism that presses against the
inside of the door frame under pressurization retracts slightly with the
opening movement of the handle.  This makes the door small enough to move
straight out through the door opening.  The outer door panel is simply a
piece of skin that fairs the door opening flush with the rest of the
fuselage. I know that when the door is opened, it first moves into the
fusleage a very small amount, perhaps an inch or so.  I assume this is to
relieve the mechanical pressure on the door so the pressure plates or
whatever they're called, can retract.  At that point the door can be
pushed forward through the opening and then swung to the side.

If my schedule allows, I will try to pay a lunchtime visit to the BFI
flightline this week and check out a passenger door on one of the 777-300s
curently in flight test. If I can figure out or ask someone how it works,
I will pass the information on to you.

As for the 767 passenger door,it retracts back into the fuselage and then
moves straight up into the overhead.  To my knowledge, it's the only plane
Boeing has ever made with this type of door.

C. Marin Faure
  author, Flying A Floatplane