JETPILOT
Topic Author
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Joined: Tue May 18, 1999 6:40 am

DC10

Wed Apr 25, 2001 12:23 pm

Can someone explain to me what the purpose of each vent on the side of this DC10, under the "E" in Northwest, controls?


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I imagine the first vent is the outflow valve?

I imagine the secod valves function is live the manhole cover on the DC8 and prevents presurizing on the ground?

The third I imagine is the over pressure relief valve?

If theses vents are associated with the pressurization system then why are they located on the foward side of the aircraft and not on the rear bottom where they are usually found?

JET
 
flyf15
Posts: 6633
Joined: Tue May 18, 1999 11:10 am

RE: DC10

Wed Apr 25, 2001 12:44 pm

Although I don't know the answer to the questions, I once saw a a pic of a United DC-10 from the 1970s which had a brownish gold stain on the side comming from these vents...presumably from the cigarette smoke onboard.
 
pmk
Posts: 609
Joined: Wed May 26, 1999 10:07 am

RE: DC10

Wed Apr 25, 2001 1:47 pm

JETPILOT:

As I have been told by an NWA ramp rat, that is one of the outlets for the A/C paks. It doesn't sound right to me but that's what I was told. But then again it was NWA, the pilots probably don't know!  Smokin cool

Peter
 
Guest

RE: DC10

Wed Apr 25, 2001 1:56 pm

That vent is the cabin pressure outflow valve. The goldish brown stains are in fact from cigarette smoke back when airlines used to allow on-board smoking. Yuck!!! Thank god they outlawed it.
 
chdmcmanus
Posts: 372
Joined: Wed Mar 21, 2001 12:53 am

RE: DC10

Wed Apr 25, 2001 2:15 pm

The actual nomenclature is the "Thrust Recovery Outflow Valve"; otherwise I believe your initial assumption is correct, although I'm not exactly sure what order they are in.
"Never trust a clean Crew Chief"
 
JETPILOT
Topic Author
Posts: 3094
Joined: Tue May 18, 1999 6:40 am

RE: DC10

Wed Apr 25, 2001 2:24 pm

The 2 doors on the fusealge right above and in front of the nose gear are the pack cooling outflow doors.

Which is the "thrust recovery outflow valve" and why is it called that?

JET

 
chdmcmanus
Posts: 372
Joined: Wed Mar 21, 2001 12:53 am

RE: DC10

Wed Apr 25, 2001 2:47 pm

The thrust recovery outflow valve is essentially the valve that controls cabin altitude throughout the isobaric selection range. It can be controlled electrically through 2 electric motors receiving input from the automatic and semi-automatic cabin pressure controller/computer. On the -10's with Flight Engineers, the clutches could be disengaged via a handle at the FE station, and the valve was then controlled through a manual wheel. I'm not sure about the later models. As far as the name is concerned, I guess it comes from the recovery of bleed air (thrust loss) to pressurization. It probably falls into the same category as why Lockheed re-named the short circuit as a "differential electrical fault"?? I'm not sure why they would put it there either. During Flight Engineer school, we covered some general DC-10 systems, and I work around them, but I have never flown one. Sorry I couldn't be more help on this one.

Regards
ChD
"Never trust a clean Crew Chief"
 
dc10hound
Posts: 460
Joined: Fri Dec 15, 2000 4:18 pm

RE: DC10

Wed Apr 25, 2001 3:16 pm

JET,
The Cabin (Over) Pressure Relief Valves (Three each, why there are are three, I don't really know) are located on the opposite side of the fuselage, almost directly across from the cabin outflow and thrust recovery valves. They live just aft of the Forward Cargo Door. Sorry, I don't have a photo of these.
Check out a MD-11 sometime. You'll see only one cabin pressure valve in the same location as three on a 10.
"Eagles soar. But weasels never get sucked into jet intakes.."
 
XFSUgimpLB41X
Posts: 3961
Joined: Fri Aug 25, 2000 1:18 am

RE: DC10

Wed Apr 25, 2001 4:15 pm

Thats the thrust recovery outflow valve, ram air vent, and butterfly valve for pressurization. The butterfly valve is closed when the plane gets airborone.
Chicks dig winglets.
 
JETPILOT
Topic Author
Posts: 3094
Joined: Tue May 18, 1999 6:40 am

RE: DC10

Wed Apr 25, 2001 4:59 pm

Going from foward to rear.....is the outflow valve, butterfly, and the ram air vent?

Whats the ram air vent used for?

Why is this on the side of the plane instead of the normal area back by the arse?

And I'm not getting the thrust recovery thing. What makes this outflow valve different from every other one on any other plane.

JET

 
VC-10
Posts: 3546
Joined: Tue Oct 26, 1999 11:34 am

RE: DC10

Wed Apr 25, 2001 5:24 pm

Going from front to rear:-

1) The Outflow Valve Ram Air Shield.
Normally this is closed but is driven open during TO roll, rotation & ldg to deflect the airstream & create a low pressure area over the outflow butterfly valve.

2) The Outflow Butterfly valve.
Controls the outflow of cabin exhaust air to maintain cabin pressure during low flight altitudes & low diff pressures.

3) Thrust Recovery Valve.
This valve controls pressurisation during moderate to hight flight Alts. It is so called due to the fact they can recover some thrust as the air spills out.

As the throttles are opened for TO the butterfly valve will modulate towards closed.

I know of one incident when someone, who should have known better, was watching from his office a '10 line up at LGW, saw a hole in the side of the a/c and got it to return to the gate. Only to find out that what he had been looking at was the open butterfly valve.

Finally, you can declutch the outflow valve sys on all '10's
 
JETPILOT
Topic Author
Posts: 3094
Joined: Tue May 18, 1999 6:40 am

RE: DC10

Wed Apr 25, 2001 6:05 pm

Thanks guys just what I was looking for.

Strange place to put that stuff.

JET
 
Guest

I Have A Question Too.

Wed Apr 25, 2001 9:35 pm

Since this is such a good digital photo and I know nothing about the DC-10,
could someone explain what those two, equally sized access panel doors are? These doors are right below the forward entrance and left and below the flag.
I assume they are for servicing the nose gear or avionics.
 
XFSUgimpLB41X
Posts: 3961
Joined: Fri Aug 25, 2000 1:18 am

RE: DC10

Wed Apr 25, 2001 10:04 pm

Just for your enjoyment, this is my last day of school, ill be heading home tommorrow, so i will type up a detailed description of the NW DC-10 pressurization system from my dad's AOM.
Chicks dig winglets.
 
VC-10
Posts: 3546
Joined: Tue Oct 26, 1999 11:34 am

RE: DC10

Wed Apr 25, 2001 10:52 pm

They are access doors to the a.c packs. #2 Pack fwd #1 pack aft.

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