777 door

Date:         02 Apr 98 01:23:59 
From:         faurecm@halcyon.com (C. Marin Faure)
Organization: NorthWest Nexus Inc.
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I believe someone in this group asked how the 777 translating door could
work since it is not a plug-type door which is held in place by the
pressurization of the cabin.  I was out on the 777 final assembly line
today and I took the opportunity to make a quick examination of the
forward passenger door of a new Air France 777.  The door is not a plug,
but is fitted with dozens of right-angle, round pads spaced around its
circumference which face out.  There are corresponding pads attached to
the door frame which face in.  When closed, the pads on the door press out
against the pads on the door frame.  This makes it impossible for the door
to be forced open, and the greater the pressurization, the tighter the
door is pressed closed.  When the door is opened, a mechanism at the top
of the door relaxes or moves to allow the entire door to move slightly
upward.  The upward movement is driven by a rotating cam device attached
to the door handle.  When the door moves up, the pads on the door no
longer oppose the pads on the door frame but are positioned just above
them, which allows the door to be pushed straight out from the fuselage
and then swung to the side.

This may not be the best explanation in the world, but that's how the door
works.  Believe it or not, the passenger doors on today's jetliners are
one of the most complex mechanical devices on the entire plane, and there
are probably more parts in one door than there are in an entire
single-engine general aviation airplane like a Cessna 180.

C. Marin Faure
  author, Flying A Floatplane