Re: Boeing 777 Cabin Door

Date:         13 Mar 98 03:35:14 
From:         faurecm@halcyon.com (C. Marin Faure)
Organization: NorthWest Nexus Inc.
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In article <airliners.1998.404@ohare.Chicago.COM>, "Ted Perez"
<tedperez@hotmail.com> wrote:

> Lately, my flight attendant wife asked me a question, "Can you show me a
> picture of the Boeing 777 cabin door, and how it works?"  Well, i've
> scoured the Internet, and... nothing.  Well, actually someone named
> Andrew sent me a scanned imaged from some training material, but it
> wasn't an actual photo of the door from an aircraft in scheduled
> operations.

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.

An interesting sidebar to the 777 door. It seems that failing hydraulics
in jetways is not that uncommon of an occurance.  When it happens, the
jetway sags down to the ground, and it can peel the door right off an
airplane in the process.  On the doors of most planes, this results in a
lot of structural damage as frames and skins are severely stressed and
bent.  The repair can take days, even weeks.  The airlines brought this up
during the desing phase of the 777 as an expensive problem they have to
deal with more than they would like.  As a result of their input, we put
some sort of shearpin mechanism (I'm not an engineer) in the door so it
would break free of the plane without damaging any of the surrounding
structure.  Our design was put to the test during a demonstration tour of
WA001, the prototype 777, to South America.  It was parked at a jetway and
everyone had just gotten off when an airport technician accidentally cut
the hydraulic pressure to the jetway.  It started to sink down on its
wheels and in the process neatly peeled the forward door right off the
777.  But the shear mechanism worked as designed; the door ripped off and
fell onto a baggage cart down below, but there was no damage at all to the
door frame, skins, or surrounding airplane structure.  A new door was air
expressed (at the airport's expense) from Seattle, and the plane was back
in the air the next day.  Replacing the door was simply a matter of
removing the remaining door parts from the hinge(s), installing the new
door, and hooking up the lights and warning circuits.

C. Marin Faure
  author, Flying A Floatplane