Re: 727 cooper vanes

Date:         08 Sep 97 02:03:43 
From:         Chris Dahler <dahler@iglobal.net>
Organization: gte.net
References:   1 2 3 4
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Steven McDowell wrote:
>
> Chris Elberfeld wrote:
> >
> > A strong wind blowing in the right direction across the tarmac can
> > deflect the Cooper switch, causing ramp wokers to have to jump
> > up and down trying pull the switch back so the rear steps can
> > be lowered.
>
> This doesn't sound too safe if these stairs are supposed to be available
> as an emergency exit.

Actually, the aft airstairs are not certified as a required emergency
exit on the B727.  They are free to be used as a exit point during an
emergency, but the airplane was certified without considering them
available.  The reason is the stairs have no emergency way of getting
them open if the fuselage is slightly twisted or comes to rest not up on
the landing gear; when you release the uplocks, hydraulic pressure from
the aircraft system helps to get the stairs down, but it is at a
dramatically reduced pressure from the system.  In order to certify the
stairs as an emergency exit, there would have to have been some sort of
high-pressure gas or hydraulic charge to forcibly blow down the stairs
in the event that normal hydraulic pressure didn't work.  I believe
there were a few 727s ordered by TWA with such a system, but not many at
all.

Chris Dahler
B-727