Re: 747 forward cargo door

Date:         08 Dec 96 04:12:31 
From:         "john r." <john@guava.demon.co.uk>
Organization: silence
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In article <airliners.1996.2711@ohare.Chicago.COM>, Jean Ludovicy
<Jean.Ludovicy@ping.be> writes
>"john r." <john@guava.demon.co.uk> wrote:
>
>>Engineering would need access to the aircraft tech.log to make and clear
>>entries, detailing damage and the fix. If you could feel the initial,
>>and susequent, bashes it must have been of consequence. Its usually the
>>metal seal strip on the door frame that gets damaged. The rubber seal is
>>pressed against the metal seal by air pressure . This always leaks a
>>little though a big leak is noisy and uses more fuel to maintain press.
>
>I can't follow you John.
> How does the packs, wich are responsible for an eventuel increase in
>fuel consumption, know that there is an additional air leak at the
>cargo door.
>Do I miss something?

If you have to put more air into the cabin to maintain pressurisation
that takes it from the engine, via the packs, and so increases fuel
consumption by reducing their efficiency.
Also air leaking at the wrong place can cause drag.
--
  _J_O_H_N____R_E_L_P_H____________   john@guava.demon.co.uk