Sponsor Message:
Aviation Technical / Operations Forum
My Starred Topics | Profile | New Topic | Forum Index | Help | Search 
Aircraft "Packs"  
User currently offlineKaddyuk From Wallis and Futuna, joined Nov 2001, 4126 posts, RR: 25
Posted (11 years 3 months 4 days 17 hours ago) and read 16430 times:

Okay, may seem like a dumb question to some,

On an aircraft, I often hear "the packs" referenced.

I know they have something to do with the air conditioning system

can anyone please explain to me why they are called packs, what they do and how they work  Smile.

Thanx Big grin


Whoever said "laughter is the best medicine" never had Gonorrhea
11 replies: All unread, jump to last
 
User currently offlineM717 From United States of America, joined Dec 2002, 608 posts, RR: 4
Reply 1, posted (11 years 3 months 4 days 17 hours ago) and read 16400 times:

Maybe urban legend, or maybe fact...

but, I heard they are called PACKs because it is an acronym for Pneumatic Air Conditioning Kit.


User currently offlineBR715-A1-30 From , joined Dec 1969, posts, RR:
Reply 2, posted (11 years 3 months 4 days 17 hours ago) and read 16398 times:

M717, That is what an AirTran captain told me. He calls them PACS though. (Pneumatic Air Conditioning System), but he said PACKs means Pneumatic Air Conditioning Kits

User currently offlineCovert From Ghana, joined Oct 2001, 1452 posts, RR: 2
Reply 3, posted (11 years 3 months 4 days 17 hours ago) and read 16395 times:

My man, take a looksee through these old threads, learn a thing or two about these pack thingys...

http://www.airliners.net/discussions/tech_ops/read.main/47968/
http://www.airliners.net/discussions/tech_ops/read.main/54792/
http://www.airliners.net/discussions/tech_ops/read.main/55007/
http://www.airliners.net/discussions/tech_ops/read.main/58546/

covert



thank goodness for TCAS !
User currently offlineM717 From United States of America, joined Dec 2002, 608 posts, RR: 4
Reply 4, posted (11 years 3 months 4 days 17 hours ago) and read 16388 times:

BR715-A1-30,

Then I guess all AirTran captains think alike.  Smile


User currently offlineKaddyuk From Wallis and Futuna, joined Nov 2001, 4126 posts, RR: 25
Reply 5, posted (11 years 3 months 4 days 17 hours ago) and read 16393 times:

Thanx m8  Smile

I am starting an apprenticeship with Virgin Atlantic in september and I dont wanna look like a doofus when asked these simple questions lol



Whoever said "laughter is the best medicine" never had Gonorrhea
User currently offlineLiamksa From Australia, joined Oct 2001, 308 posts, RR: 0
Reply 6, posted (11 years 3 months 4 days 11 hours ago) and read 16325 times:

This is a straight copy & paste courtesy of Cdfmxtech

Pressurization and
Air
Conditioning
Kit

http://www.airliners.net/discussions/tech_ops/read.main/56247/  Smile


User currently offlineLstc From Canada, joined Jun 2003, 320 posts, RR: 0
Reply 7, posted (11 years 3 months 4 days 10 hours ago) and read 16321 times:

Very old aircraft maintenance manuals referred to the air conditioning "packages". It has been shortened to "pac" or "pack" since then. The air conditioning system has little directly to do with pressurization control. So when we refer to the packs we DO NOT mean the outflow valves or associated pressure controller(s).

The urban legend comes from younger guys making up acronyms to quell curiosity.

 Smile


User currently offlineAaron atp From United States of America, joined Mar 2000, 533 posts, RR: 2
Reply 8, posted (11 years 3 months 4 days 10 hours ago) and read 16310 times:

where the real information is...
http://www.airliners.net/discussions/tech_ops/read.main/27236/4/
http://www.airliners.net/discussions/tech_ops/read.main/31097/4/


User currently offlineCovert From Ghana, joined Oct 2001, 1452 posts, RR: 2
Reply 9, posted (11 years 3 months 4 days 9 hours ago) and read 16305 times:

Goodness Aaron, whatever happened to such technical discussions? That one thread was over 200 posts! It has seemed like we have lost something lately here.....

covert



thank goodness for TCAS !
User currently offline737doctor From United States of America, joined Mar 2001, 1332 posts, RR: 39
Reply 10, posted (11 years 3 months 4 days 7 hours ago) and read 16288 times:

If you don't want to wade through the 200+ posts in that ACM pissing contest above, I will give you a more condensed version as it applies to the 737-700, which has two packs (one on each side) located in the A/C bays on the belly of the aircraft forward of the main gear wheel wells.

It's important to note that there other important components that work with the pack, in order to provide temperature control.

First of all, you must have a bleed air source (either from your engines or APU)and a means of control.

When you turn on a pack by placing its respective switch in either AUTO or HIGH, AC power is supplied to the air conditioning accessory unit (ACAU), located in the E&E compartment between the nose gear wheel well and forward cargo compartment. The ACAU contains the relays that control pack operation once you turn it on. The ACAU opens the flow control and shutoff valve, allowing bleed air to flow into the pack. It isn't until the air hits the turbine of the ACM that it actually does any "work"; more about that later.

The ACM has a single shaft on which you have a turbine, compressor and impeller fan. The fan helps pull air through the ram air duct (those two openings you see on the belly of the aircraft forward of the main gear wheel wells) and through the heat exchangers of which there are two, primary and secondary. Think of them as the radiator in your car, except they use ram air instead of water to cool the bleed air.

The primary heat exchanger cools the bleed air before it passes into the compressor of the ACM. The compressor increases the pressure of the air (go figure) which also increases the temperature. It then passes through the secondary heat exchanger which cools it down again before entering the turbine of the ACM. The air hits the turbine and "expands" causing the pressure and temperature to rapidly drop. Immediately downstream of the turbine is a water separator which swirls the air through a "sock", causing the condensed water to collect in a drain. This water is then sprayed into the ram air flow.

A 35 degree system prevents the water from freezing in the water separator by using some of the warm air from the primary heat exchanger through a low limit valve when a freezing condition is sensed.

The air mix valve then mixes hot bleed air and cold air from the ACM to provide the desired temperature selected in the cockpit.

Without drawing a picture, it's kind of hard to explain. I hope I helped without getting into too great of detail.



Patrick Bateman is my hero.
User currently offlineAaron atp From United States of America, joined Mar 2000, 533 posts, RR: 2
Reply 11, posted (11 years 3 months 1 day 19 hours ago) and read 16164 times:

It's not the aircraft he described, but here is the ACM from the G4 and some pics. The basic operation is the same. These are the same as the broken links in my posts to that monster thread.













Top Of Page
Forum Index

Reply To This Topic Aircraft "Packs"
Username:
No username? Sign up now!
Password: 


Forgot Password? Be reminded.
Remember me on this computer (uses cookies)
  • Tech/Ops related posts only!
  • Not Tech/Ops related? Use the other forums
  • No adverts of any kind. This includes web pages.
  • No hostile language or criticizing of others.
  • Do not post copyright protected material.
  • Use relevant and describing topics.
  • Check if your post already been discussed.
  • Check your spelling!
  • DETAILED RULES
Add Images Add SmiliesPosting Help

Please check your spelling (press "Check Spelling" above)


Similar topics:More similar topics...
Aircraft "Bridging" Question posted Mon Oct 6 2003 04:02:08 by CanadaEH
Aircraft "Packs" posted Fri Jul 25 2003 22:49:09 by Kaddyuk
Aircraft "Eyebrow" Windows posted Fri Jul 11 2003 23:47:36 by Cancidas
Pedal To The Metal While "driving" An Aircraft? posted Thu Jan 14 2010 09:54:26 by Alwaysontherun
"Rebooting" The Aircraft. posted Wed Oct 14 2009 01:42:39 by SashA
B2 Style "rudder" On Conventional Aircraft? posted Mon Feb 18 2008 13:14:06 by Flexo
The Ultimative "Why Do Aircraft Fly?" Question... posted Wed Aug 8 2007 22:26:45 by Superstring
"Black Boxes" On Light Aircraft? posted Sat Mar 3 2007 22:50:42 by TupolevTu154
Do Aircraft Controls Have To Be "calibrated"? posted Sun Nov 12 2006 21:26:09 by Jamesbuk
"Spare Turns" - Aircraft Crew posted Sat Oct 7 2006 23:30:00 by Goinv

Sponsor Message:
Printer friendly format