B737 Question Regarding APU Hole — Tech Ops Forum

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B737 Question Regarding APU Hole

Turbotrent From Belgium, joined Jan 2002, 152 posts, RR: 2
Posted (10 years 1 week 9 hours ago) and read 1756 times:

Hello everyone,

Yesterday I was looking at the new pictures in de database and I came across this one :

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Photo © Lee Archer

I have never realised that there were 2 'holes' at the very end of a B737. I assume that the biggest hole is the outlet for the APU, but what is the first, smaller hole for?
BTW, Very nice picture Lee!

Best regards,

Tom

Man's flight through life is sustained by the power of his knowledge.

4 replies: All unread, jump to last

Avioniker From United States of America, joined Dec 2001, 1109 posts, RR: 11
Reply 1, posted (10 years 1 week 9 hours ago) and read 1718 times:

In the NG 737's the APU cooling air is provided by an eductor system. The air is drawn in by venturi (for lack of a better term) action and flows across the oil cooler and through the compartment before being extracted through a jacket surrounding the exhaust duct. The upper hole is the air inlet. (I might add that it is exactly the size prefered by the pigmy barn owl for its nest.)
Here's a link
http://www.b737.org.uk/apu.htm

One may educate the ignorance from the unknowing but stupid is forever. Boswell; ca: 1533

FredT From United Kingdom, joined Feb 2002, 2184 posts, RR: 26
Reply 2, posted (10 years 1 week 8 hours ago) and read 1706 times:

"(I might add that it is exactly the size prefered by the pigmy barn owl for its nest.)"

Now that is exactly the kind of critical information that is always omitted from maintenance manuals! Experience at it's best. Smile

Cheers,
Fred, tech pubs guy

I thought I was doing good trying to avoid those airport hotels... and look at me now.

Turbotrent From Belgium, joined Jan 2002, 152 posts, RR: 2
Reply 3, posted (10 years 6 days 13 hours ago) and read 1604 times:

Thanks for your replies guys!

Avioniker, very interesting website you gave me!

Best regards,

Tom

Man's flight through life is sustained by the power of his knowledge.

737doctor From United States of America, joined Mar 2001, 1332 posts, RR: 47
Reply 4, posted (10 years 4 days 4 hours ago) and read 1487 times:

Turbotrent,

I recently had this photo accepted which gives an excellent view of the NG 737 APU exhaust of which you speak. Since it is pertinent to the discussion, I thought you might enjoy it.

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