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PACKs, BLEEDs...

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Sheva View Drop Down
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    Posted: August-28-2006 at 4:18pm
Hi there,
Ive been flying this bird for sime time now but Im not sure about those things until today - Its PACKs and BLEEDs. Would somebody be so kind and explain me this in few sentences?
I red the manual but Im not so clever from it.
Thanks in advance
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wlaziu View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote wlaziu Quote  Post ReplyReply Direct Link To This Post Posted: August-29-2006 at 11:57am
Hi!

Bleeds are the bleed air valves that control the flow of the bleed air (a compressed air) from the engines. Bleed air is taken form the compressor (low or high stage) in the engine. Bleed air is needed to provide fresh air in the cabin, heating of the cabin (because compressing the air makes it hot), use of the leading edge/inlet de-ice boots and air pressurization at high altitiudes (because the cabin isn't so hermetic at all). Usage of the bleed air comes at a cost of some engine power (thus they should be turned off if the T/O runway is pretty short) and increased fuel consumption.

That compressed air is called bleed air because it's creation requires some energy to be bleed from the engine.

To sum up about the bleed valve switches. They decide wheather all the air that comes thru the engine inlet goes to the combustion chamber or some of it goes to the aircraft systems.


After passing the bleed valve the air is distributed to two main ATR systems: The Air conditioning (form the low stage compressor if possible or from high stage compressor) and to the de-icing (from the high stage compressor)
- As for the de-icng it is then distributed to engine air intakes and to the airframe boots which divides to the horiznotal stab boots and wing boots which divides to inner wing boots and outer wing boots)
- As for the air conditioning, the air is distributed to two pack (Pressurization and Air Conditioning) valves which decide if the bleed air is ok (press/temp) to give it a go to passengers. The last stage before the air enters the cabin is the heat exchanger which regulates the air temp (coz the air is still hot). Then the air goes to the respective packs Pack1 provides the nice air flow from the overhead compartment to passengers on the left (its duct is extended to the cockpit), Pack 2 to the pax on the right. Both packs can be supplied from single engine via the GRD X-FEED valve.

OK now about the controls.
- Pack valve switch decides weather the air is supplied to the given pack or not.
-Air flow works just the same as the setting of the fan speed in a car if you set to high you get a higher airflow thus getting faster cabin heating or cooling at a cost of greater noise of the flowing air.
-Temperature selector button selects how the air temp is set. If AUTO the MFC tries to suit every passenger need. If manual captain decides about the air temp for all pax via those two temperature rotary selectors
-The recirculation fans are installed to get the air moving thru the cabin (probably to reduce dust collecting on the floor ). Thanks to them pax can fell greater air flow then there really is.

It must be rembered that in case of single bleed air valve failure (for example eng failure) the other one will not be able to provide sufficient air pressurization above FL 200.

I Hope this has clariffied a bit the bleeds
You can find more info on wikipedia.

With regards Marek
Copernicus hold down the world, I have to get off.
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Sheva View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Sheva Quote  Post ReplyReply Direct Link To This Post Posted: August-29-2006 at 5:15pm
Thanks alot
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Sheva View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Sheva Quote  Post ReplyReply Direct Link To This Post Posted: August-29-2006 at 6:19pm
BTW where did you find this?
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wlaziu View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote wlaziu Quote  Post ReplyReply Direct Link To This Post Posted: August-30-2006 at 12:54pm
Well.
hmm in the manual of the ATR (pneumatic system and ice protection)
http://en.wikipedia.org/wiki/Bleed_air
http://en.wikipedia.org/wiki/Jet_turbine
http://en.wikipedia.org/wiki/Turboprop

There is also a great site in polish that explains well on how diffrent type of engines work
http://www.polatca.pata.pl/papierki/hist_lotn/h_jet.htm
http://www.polatca.pata.pl/papierki/hist_lotn/h_tprop.htm

you can try this translator to read the text partially
http://translate.pl/

Copernicus hold down the world, I have to get off.
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Sheva View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Sheva Quote  Post ReplyReply Direct Link To This Post Posted: August-30-2006 at 5:39pm
Thanks
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Sameenshah View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Sameenshah Quote  Post ReplyReply Direct Link To This Post Posted: December-24-2017 at 10:11am
hello everyone i need to know about p3 adaptor
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