Re: Boeing 777 Cabin Door

Date:         24 Mar 98 11:38:51 
From:         faurecm@halcyon.com (C. Marin Faure)
Organization: NorthWest Nexus Inc.
References:   1 2
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In article <airliners.1998.459@ohare.Chicago.COM>, Julian Fitzherbert
<julian@gatwick.geco-prakla.slb.com> wrote:

> In article <airliners.1998.429@ohare.chicago.com>,
>         faurecm@halcyon.com (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.
>
> I've seen some 777 descriptions (can't offhand remember which) that suggest
> Boeing invented this type of door for the 777. Is it really that special?

I'm not an engineer, so I don't know what sort of mechanical or design
innovations are contained within the 777 door.  I'm sure there are seveal
features that make it unique and better than previous doors.  But the
general concept of a translating door is not new.  Airbus has used this
type of door on some (or all) of its models for years.  In fact, Boeing
sent at least one engineer on a bunch of commercial Airbus flights to
observe how well the translating door worked in everyday service. Was it
easy for cabin attendants and ramp agents to open?  Did it interfere with
boarding and catering equipment?  Was it more maintenance-free than
conventional plug doors?  And so on.

> > 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.
>
> Whether a VC10 door frame would survive this I don't know :)

Now this IS a 777 innovation, I believe.  The deliberately designed "weak
links" that are incorporated into the door's hinge mechanism were in
response to the airlines' concerns about airframe damage when a jetway
sinks its weight down an open door (any door, not just a translating
door).  To my knowledge, the 777 is the only plane (so far) to have
addressed this issue with a door mechanism designed to break away cleanly
if the jetway falls on it, this saving the airline a tremendous amount of
repair costs.  And as I pointed out in a previous post, this feature was
"tested" on WA001, the prototype 777, when a jetway in South America did
just that, and peeled one of the forward passenger doors right off the
plane and dumped it onto a baggage cart that happened to be sitting down
below. A new door was flown in from Seattle that evening and installed and
WA001 was airworthy and flew out on schedule the next day.  In the old
days, this mishap would have laid up the plane for days if not weeks as
damaged skin and doorframe components were removed and replaced.

I filmed the door icing tests that were performed on the 777 door back in
the early 1990s, and I can attest to the ease with which what in reality
is a very large door can be opened (with or without ice covering it).  But
while the 777 translating door is a beautifully designed unit and seems
very easy to use in the field, the concept is not a 777 exclusive.

C. Marin Faure
  author, Flying A Floatplane