peteschiller
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Pressurization In Cargo Planes?

Fri May 28, 2010 11:45 pm

Think it's a simple question, but can't find the answer anywhere: are cargo freighters pressurized?

I speculate that a cargo plane with an enormous door that swings shut from the outside would not be pressurized. BUT, then again, that would mean that the cockpit would have to be sealed off from the rest of the plane with a bulkhead, and it's not, right? Further, UAL 811 lost its cargo door due to a "pressure differential": http://en.wikipedia.org/wiki/United_Airlines_Flight_811
 
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RE: Pressurization In Cargo Planes?

Sat May 29, 2010 12:03 am

Quoting peteschiller (Thread starter):
are cargo freighters pressurized?


Yes, just like passenger aircraft.
 
fr8mech
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RE: Pressurization In Cargo Planes?

Sat May 29, 2010 12:04 am

Cargo aircraft are pressurized, just like their passenger counterparts.
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airtran737
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RE: Pressurization In Cargo Planes?

Sat May 29, 2010 1:28 am

They are fully pressurized. Most freighters have a curtain barrier, so the entire thing has to be pressurized. Plus, there's nothing like taking a bottle of oxygen in the back and sleeping on an empty pallet.
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flybaurlax
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RE: Pressurization In Cargo Planes?

Sat May 29, 2010 4:11 am

When C-17s do airdrops at higher altitudes the crew have to suck the hose so they can depressurize and open the door.
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Braniff747SP
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RE: Pressurization In Cargo Planes?

Sat May 29, 2010 6:30 am

Normal freighters a pressurised, but I believe Airbus' Beluga is not.
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CCA
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RE: Pressurization In Cargo Planes?

Sat May 29, 2010 7:18 am

Quoting Braniff747SP (Reply 5):
Normal freighters a pressurised, but I believe Airbus' Beluga is not.

The Cockpit of the beluga is pressurised similar to the 747LCF which has a pressure bulkhead at STA520 making section 41 the pressurised area.
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AA737-823
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RE: Pressurization In Cargo Planes?

Sat May 29, 2010 9:33 am

You have to keep in mind that PRESSURIZATION and TEMPERATURE CONTROL go hand-in-hand.
The heat comes off of the engine bleeds, through the AC Packs, and into the cabin. It is then 'bottled up' by the outflow valve, which prevents it from escaping willy-nilly.
So, since we typically want our freight heated (particularly when there is live freight on board, which happens much more often than people imagine), we must run the packs and outflow valve(s) in such a manner that will keep the plane at a safe temperature.
Heat aside, any animals (I've seen frogs, ferrets, turtles, cats, dogs, horses galore, and more) will definitely need breathable atmosphere!

So yes, generally speaking, pressurized.

Regarding the large doors (I'm surprised you didn't consider the 747-400M that KLM and others fly- large cargo door in the passenger cabin... still definitely pressurized!), there are very sturdy locking mechanisms involved in closing these doors. Typically, they work great.
 
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HAWK21M
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RE: Pressurization In Cargo Planes?

Sat May 29, 2010 10:29 am

Cargo Aircraft are pressurized like other Commercial Aircraft.
Only to add some do have a Seperation barrier from the Flight deck to the Main deck in case of a fire,so Airflow can be shut to the zone where the fire exists in enabling supression of the fire.
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CosmicCruiser
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RE: Pressurization In Cargo Planes?

Sat May 29, 2010 1:28 pm

Quoting HAWK21M (Reply 8):
Only to add some do have a Seperation barrier from the Flight deck to the Main deck in case of a fire,so Airflow can be shut to the zone where the fire exists in enabling supression of the fire.

In ours the barrier/curtain is only for smoke control. It is not airtight per se. Fire control is done by sutting off the air to the main cabin. We also are now installing a fire suppression system that can actually detect the hot can, thrust a nozzle into it and shoot it full of suppressant.
 
tf39
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RE: Pressurization In Cargo Planes?

Sun May 30, 2010 3:12 am

I was just reading (Antonov's Heavy Transports) that the AN-124 ensures a pressure differential of 7.82 PSI for both upper cabins but 3.57 PSI in the cargo hold.
 
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RE: Pressurization In Cargo Planes?

Sun May 30, 2010 3:18 am

Many of the old DC-6 cargo planes deactivated pressurization systems but, of course, that results in their being restricted to flying at low altitudes. Cargo jets are just the same as any other airliner. Security of cargo doors is very important!
 
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HAWK21M
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RE: Pressurization In Cargo Planes?

Sun May 30, 2010 8:40 am

Quoting CosmicCruiser (Reply 9):
It is not airtight per se. Fire control is done by sutting off the air to the main cabin

If its not Airtight,How would you stop Oxygen reaching the flames in case of a fire,as the MOV shutoff will not serve the purpose,as there is no Fire Extinguisher Installed.
The Fire is Extinguished by Starvation of Oxygen to the area.

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MD11Engineer
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RE: Pressurization In Cargo Planes?

Sun May 30, 2010 9:26 am

Quoting HAWK21M (Reply 12):
Quoting CosmicCruiser (Reply 9):
It is not airtight per se. Fire control is done by sutting off the air to the main cabin

If its not Airtight,How would you stop Oxygen reaching the flames in case of a fire,as the MOV shutoff will not serve the purpose,as there is no Fire Extinguisher Installed.
The Fire is Extinguished by Starvation of Oxygen to the area.

regds
MEL.

The crew will don oxygen masks and depressurize the cabin. At 30.000 ft this will do the job.
Generally cargo planes, which derived from passenger aircraft, are fully pressurized. Some dedicated cargo aircraft, like the AN-124, only have the crew sections pressurized.

Jan
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CosmicCruiser
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RE: Pressurization In Cargo Planes?

Sun May 30, 2010 7:50 pm

Quoting HAWK21M (Reply 12):
If its not Airtight,How would you stop Oxygen reaching the flames in case of a fire,as the MOV shutoff will not serve the purpose,as there is no Fire Extinguisher Installed.

AS MD11Mechanic said we shut off the air to the cabin, not the cockpit, and manually raise the cab alt to 25,000'. The crew will be on O2 and the fire should die. We have fire ext. for the haz containers and some now have the new FSS Fire Suppression System. This procedure worked perfect on our DC-10 a few yrs ago that landed in Stewart NY with a cargo fire. The fire was suppressed until they opened the cargo door on the grd. then it flared up and the plane burned.
 
remcor
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RE: Pressurization In Cargo Planes?

Thu Jan 20, 2011 12:56 am

Bringing back this 6 year old post because one question wasn't answered.

It seems that most cargo aircraft do indeed have pressurized holds, however... do they pressurize them to the same level as passenger aircraft?

For instance, perhaps a 77W is kept pressurized to a 7000' level (FAA mandates 8000' or less), but the 777F might be kept pressurized at a 10000' level. The (hypothetical) advantage for the carrier is that is causes less stress on the airframe, reducing maintenance.

Someone at my company asked me a cabin pressure question for a highly complex instrument we're planning to ship and it got me thinking. Anyone have a clue to whether a cargo craft will be kept pressurized at the same level as a similar passenger aircraft?
 
DH106
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RE: Pressurization In Cargo Planes?

Thu Jan 20, 2011 8:41 am

Quoting HAWK21M (Reply 8):
Cargo Aircraft are pressurized like other Commercial Aircraft.

How about older vintage aircraft like the C-130, An-12 - I didn't think they were pressurised ?
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BreninTW
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RE: Pressurization In Cargo Planes?

Thu Jan 20, 2011 8:58 am

Quoting remcor (Reply 15):
For instance, perhaps a 77W is kept pressurized to a 7000' level (FAA mandates 8000' or less), but the 777F might be kept pressurized at a 10000' level. The (hypothetical) advantage for the carrier is that is causes less stress on the airframe, reducing maintenance.


If you don't have differential pressurization, you're going to have pilots who aren't going to be happy flying an aircraft that is constantly trying to starve them of oxygen -- and I don't think the relief crew will like having to cart an oxygen bottle with them everywhere. A cabin altitude of 10,000' may be safe for short periods of time -- for a flight of a good few hours, hypoxia is going to set in, which will lead to errors being made and planes crashed.

I would imagine that differential pressurization like that would require a bulkhead of some sort between the cockpit/crew areas and the rest of the plane. That adds weight and complexity to the aircraft.

Now, I've never been on a 777F, I have been on a 744F. There was direct access between the upper deck and the cargo hold. It wasn't air-tight, so the crew area would be the same pressure as the hold.

Cargo aircraft that are derived from passenger aircraft will normally have the same climate control system as the PAX equivalent -- it reduces development and certification costs to keep an existing system. So, it stands to reason that they would be pressurized to the same altitude as the PAX equivalents.
 
oly720man
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RE: Pressurization In Cargo Planes?

Thu Jan 20, 2011 10:36 am

Quoting DH106 (Reply 16):
How about older vintage aircraft like the C-130, An-12 - I didn't think they were pressurised ?

C-130 is the An12 isn't, but the Chinese An-12, the Y-8, is pressurised according to this

http://forum.keypublishing.co.uk/archive/index.php?t-22738.html
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fr8mech
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RE: Pressurization In Cargo Planes?

Thu Jan 20, 2011 8:55 pm

Quoting remcor (Reply 15):
It seems that most cargo aircraft do indeed have pressurized holds, however... do they pressurize them to the same level as passenger aircraft?

Yes, they are pressurized to the same level or PSID. I recall that the classic jumbos had a different schedule, but the end result was the same...about an 8000' cabin.

I will add the proviso that this is on aircraft that I'm familiar with. There may be others that do have a different end result.
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KELPkid
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RE: Pressurization In Cargo Planes?

Fri Jan 21, 2011 5:28 am

Quoting MD11Engineer (Reply 13):
Generally cargo planes, which derived from passenger aircraft, are fully pressurized. Some dedicated cargo aircraft, like the AN-124, only have the crew sections pressurized.

Most US designs feature a pressurized cargo deck. This is because they are designed for medivac and troop transport roles as well as transporting equipment.
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RE: Pressurization In Cargo Planes?

Sun Jan 23, 2011 2:18 am

Quoting KELPkid (Reply 20):
Quoting MD11Engineer (Reply 13):
Generally cargo planes, which derived from passenger aircraft, are fully pressurized. Some dedicated cargo aircraft, like the AN-124, only have the crew sections pressurized.

So that means the AN225 is not fully pressurized either. It seems to restrict the type of cargo quite a bit. Can they guarantee +0° C temperatures at least?
 
c5load
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RE: Pressurization In Cargo Planes?

Sun Jan 23, 2011 3:01 am

Quoting MD11Engineer (Reply 13):
Generally cargo planes, which derived from passenger aircraft, are fully pressurized. Some dedicated cargo aircraft, like the AN-124, only have the crew sections pressurized.

The C-5 is fully pressurized. However, that may be due to the fact that when Lockheed manufactured it, there were palletized seat kits that could be installed in the cargo box.

Quoting peteschiller (Thread starter):
I speculate that a cargo plane with an enormous door that swings shut from the outside would not be pressurized.

Our entire nose swings open, wouldn't that be considered a large door? But, we do have large bayonet locks that hold that thing in place.
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HAWK21M
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RE: Pressurization In Cargo Planes?

Sun Jan 23, 2011 11:19 am

Is the LCF Main deck Pressurized.....?.
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Jetlagged
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RE: Pressurization In Cargo Planes?

Sun Jan 23, 2011 11:44 am

Quoting remcor (Reply 15):
It seems that most cargo aircraft do indeed have pressurized holds, however... do they pressurize them to the same level as passenger aircraft?

747 Classic freighters can have a different pressurisation schedule to passenger versions. This allows a higher cruise cabin altitude. I can't remember the exact difference but it was something around 1000 feet higher for a typical cruise flight level.

The aircraft used the same pressure control panel, but the cruise altitude select window has two scales, one for cargo and one for pax. One or other scale is covered by a screw-on metal plate so only the appropriate one is visible.

[Edited 2011-01-23 03:49:03]
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RE: Pressurization In Cargo Planes?

Sun Jan 23, 2011 12:23 pm

Quoting HAWK21M (Reply 23):
Is the LCF Main deck Pressurized.....?.

Nope.
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