Re: MD-80: Lawn Dart or Efficient Design?

From:         "David G. Davidson" <>
Date:         05 Nov 96 04:13:58 
References:   1 2
Next article
View raw article
  or MIME structure wrote:
> In article <airliners.1996.2156@ohare.Chicago.COM>, David Lednicer
> <> writes:
> >> Can anyone describe to me what the 727 APU installation actually is?
> >
> >       The APU is in the main gear bay, on the centerline, behind the
> >rear spar.  The APU is actually situated in a hole in the fuselage keel
> >beam.  Inlet air comes from the gear bay (I believe the gear must be
> >down to run the APU) and exhausts through a exit in the right hand upper
> >wing skin.
> Thanks for the various answers to my question. Just one more
> clarification....How high is the under surface of the wing?  Are there any
> problems with FOD being sucked up into the APU?
> Gerald Wilson

Ok, here's the deal on the 727 APU.

It is mounted in a hole in the keel beam in the forward end of the wheel
well and hangs from the ceiling of the wheel well.

The portion of the APU with the gearbox, electrical generator, starter,
fuel control, oil pump and oil filter is in the left wheel well.

The portion of the APU which contains the combustion chamber, ignitor
plug and box, turbine wheel and the APU load valve (the valve which
turns pneumatics to the airplane on and off) is in the right wheel well.

The APU exhaust exits through the top of the right wing, just a little
aft of the rear overwing exit.

The air inlets for the APU are in the left wheel well and are protected
from FOD by the left gear door which is normally closed. One of the air
inlets is for cooling the electrical generator. The other feeds air to
the APU compressor section.

The bottom of the wing is about 6 feet off the ground.

This is kind of hard to visualize. Is there a way to post pictures to
this group? Maybe I'll just throw some pictures together and put them on
a web page.