falter
Topic Author
Posts: 27
Joined: Tue Jan 07, 2014 4:18 am

DC10 door operation

Sun Apr 21, 2019 9:31 pm

Just a question about DC-10 doors after watching a training video.

I noticed they appear to be mechanically operated - ie. the attendant pulls a lever or presses a button, and the door pulls itself up or slides back down and locks in. I'm curious, is this done by electrical power? If so, what happens in a crash situation where power is lost?
 
strfyr51
Posts: 3753
Joined: Tue Apr 10, 2012 5:04 pm

Re: DC10 door operation

Sun Apr 21, 2019 10:56 pm

falter wrote:
Just a question about DC-10 doors after watching a training video.

I noticed they appear to be mechanically operated - ie. the attendant pulls a lever or presses a button, and the door pulls itself up or slides back down and locks in. I'm curious, is this done by electrical power? If so, what happens in a crash situation where power is lost?

the door can be opened and closed manually with or without power as they are counterweighted.
 
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XAM2175
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Re: DC10 door operation

Mon Apr 22, 2019 12:33 am

strfyr51 wrote:
falter wrote:
... is this done by electrical power? If so, what happens in a crash situation where power is lost?

the door can be opened and closed manually with or without power as they are counterweighted.


This has been covered a here a few times in the past, but in short - yes, in normal operation the door is moved by electric motors.
In an emergency (contrary to strfyr51's post) a compressed-air bottle is used to force them open.

Counterweight systems were however used on the L-1011 and 767, the latter in particular being sufficiently-well balanced that the doors could easily be opened and closed by hand even when power was available.
 
falter
Topic Author
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Re: DC10 door operation

Mon Apr 22, 2019 3:40 am

Yes my apologies, I did google first but must have been using the wrong terms as now I'm seeing all kinds of stuff.

A further question: is the compressed air bottle powerful enough to overcome pressurization? Like if you crash landed and somehow maintained pressure (I'm not sure if that's possible), could the bottle force the doors open?
 
stratclub
Posts: 1241
Joined: Fri Jan 05, 2018 10:38 pm

Re: DC10 door operation

Mon Apr 22, 2019 5:07 am

falter wrote:
Yes my apologies, I did google first but must have been using the wrong terms as now I'm seeing all kinds of stuff.

A further question: is the compressed air bottle powerful enough to overcome pressurization? Like if you crash landed and somehow maintained pressure (I'm not sure if that's possible), could the bottle force the doors open?

Just a guess, but I would say probably not. Even with 1 psi of cabin differential there are 144 square inches per foot (Approx. 2,100 pounds) of the doors surface area pushing the door against the doors support fittings.

I really couldn't imagine an aircraft just crash landing and still being pressurized. If you landed at a high altitude airport such as El Alto (13,323 feet) I suppose it could be possible but extremely unlikely to still land pressurized for several reasons. I'm not a pilot. Maybe a pilot could check in and better explain the why.
 
slcguy
Posts: 342
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Re: DC10 door operation

Mon Apr 22, 2019 6:31 am

stratclub wrote:
falter wrote:
Yes my apologies, I did google first but must have been using the wrong terms as now I'm seeing all kinds of stuff.

A further question: is the compressed air bottle powerful enough to overcome pressurization? Like if you crash landed and somehow maintained pressure (I'm not sure if that's possible), could the bottle force the doors open?

Just a guess, but I would say probably not. Even with 1 psi of cabin differential there are 144 square inches per foot (Approx. 2,100 pounds) of the doors surface area pushing the door against the doors support fittings.

I really couldn't imagine an aircraft just crash landing and still being pressurized. If you landed at a high altitude airport such as El Alto (13,323 feet) I suppose it could be possible but extremely unlikely to still land pressurized for several reasons. I'm not a pilot. Maybe a pilot could check in and better explain the why.


I agree, would be highly unlikely/impossible to remain pressurized after a landing or crash. As for doors, it doesn't matter what type, vertical sliding doors manual/powered or swing open manual doors, impossible to open when pressurized because of the plug design.
 
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XAM2175
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Re: DC10 door operation

Mon Apr 22, 2019 6:01 pm

Actually, the door is "unplugged" manually by the action of using the Emergency Open handle, after which the air is discharged. If by some freak chance the aircraft was still pressurised, it wouldn't be possible for the person operating the handle to overcome the difference.

You may be interested in this training video for the DC-10 made by Canadian Airlines, which covers door operation:
https://www.youtube.com/watch?v=R37pftDR9Ss

Compare it with the 767's procedures:
https://www.youtube.com/watch?v=ajKl_kDFGko
 
strfyr51
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Joined: Tue Apr 10, 2012 5:04 pm

Re: DC10 door operation

Mon Apr 22, 2019 9:25 pm

XAM2175 wrote:
strfyr51 wrote:
falter wrote:
... is this done by electrical power? If so, what happens in a crash situation where power is lost?

the door can be opened and closed manually with or without power as they are counterweighted.


This has been covered a here a few times in the past, but in short - yes, in normal operation the door is moved by electric motors.
In an emergency (contrary to strfyr51's post) a compressed-air bottle is used to force them open.

Counterweight systems were however used on the L-1011 and 767, the latter in particular being sufficiently-well balanced that the doors could easily be opened and closed by hand even when power was available.

I went out to and worked on DC10's in the rain at SFO and didn't always use power, the door wasn't at all hard to open once you pulled it In, It did NOT require power to open, though it was electrically powered. And? I was a specialist on Dorr rigging and repairs. It wasn't any big deal. However? We could NOT dispatch the airplane unless the door opened and closed electrically.
 
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XAM2175
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Re: DC10 door operation

Mon Apr 22, 2019 9:41 pm

strfyr51 wrote:
It did NOT require power to open, though it was electrically powered.


Ah, sorry mate, I misunderstood you - yeah the doors could be manually operated, but the air tank was there to blow it open in an emergency. By contrast, the 767's doors used the counterweight both for manual ops and emergencies.
 
Apprentice
Posts: 777
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Re: DC10 door operation

Sun Apr 28, 2019 4:30 am

Hi, Three ways to open Pax Doors On DC-10
1. Electrical, after lock is moved to unlock, a micro “electrical powered” handle (in old version, with handle painted gray complete), activating handle, you remove latches and, after they are open, a micro powers door actuator, that open.
2. Pneumatic, when no power to Ground Circuit is available, moving unlock handle to “Over” (Pass normal “unlock” position), holding that way and moving gray handle all the way up, a seal in the N2 bottle is broken and N2 move an Pneumatic (Air) actuator and move the door open.
3. Manual. Last but not.. with help of two big man, FA hold again unlock overdrive handle and holding there, (overdrive), “ the men, who should be instructed, hold the horizontal bar, located at aproxima 1/3 from the floor and, pushing up, try to open it.

Note: On “newer” models, Emergency Handle is painted with red Lin’s to indicate that should be operated only in emergency. In normal mode, Door will be operated from two small electrical Push Button located on top of respective FA’s station.

Restore door, to normal operating condition, after any emergency, it is a time consuming task, performing mainly at door. A/c will fly with inop doors in dependence of pax qty.. (MEL)

Rgds
“An4; IL18; IL6; Tu5; D10; MD11; MD83; B32; B34: B37; B744; B748; B752; B763; B772; B773; B77W; A320; A332; A333; A342; A343.
"A NO" is a positive answer., "DON'T KNOW" is not. My Tutor (a wise man)
“CUBANA” 90 years Flying”
 
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Horstroad
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Re: DC10 door operation

Sun Apr 28, 2019 8:53 am

strfyr51 wrote:
the door can be opened and closed manually with or without power as they are counterweighted.

XAM2175 wrote:
In an emergency (contrary to strfyr51's post) a compressed-air bottle is used to force them open.

strfyr51 wrote:
the door wasn't at all hard to open once you pulled it In, It did NOT require power to open

Apprentice wrote:
3. Manual. Last but not.. with help of two big man, FA hold again unlock overdrive handle and holding there, (overdrive), “ the men, who should be instructed, hold the horizontal bar, located at aproxima 1/3 from the floor and, pushing up, try to open it.


Now I'm confused. Was it or was it not counterbalanced?
I only know the MD11 door and I always was under the impression that it's basically the same... except for the electrical switch that changed shape over time.
The door is very heavy. Maybe less so when in an emergency the slide stays on the ground? I've never tried it without the slide. But with the slide it's impossible to open it alone.
According to the AMM the door weighs between 106 and 180kg. The bare door without anything weighs 59kg. Also you would have to lift it against the resistance of the air motor.
So not an easy task at all without any counterweights/springs.
 
slcguy
Posts: 342
Joined: Wed Jul 09, 2008 12:09 pm

Re: DC10 door operation

Sun Apr 28, 2019 3:22 pm

Cannot speak about a DC-10 or L-1011 door but on the 767 the door is powered. A 767 door can be opened and closed manually when power is not available but it does take some effort. Not something a flight attendant or gate agent would want to do on a regular basis. The door must have some sort of counter balance because there is no tendency to slide up or down, in fact it is harder to pull the door down and close it is than it is to open and raise it.
 
BravoOne
Posts: 3356
Joined: Fri Apr 12, 2013 2:27 pm

Re: DC10 door operation

Sun Apr 28, 2019 6:24 pm

slcguy wrote:
Cannot speak about a DC-10 or L-1011 door but on the 767 the door is powered. A 767 door can be opened and closed manually when power is not available but it does take some effort. Not something a flight attendant or gate agent would want to do on a regular basis. The door must have some sort of counter balance because there is no tendency to slide up or down, in fact it is harder to pull the door down and close it is than it is to open and raise it.


May have missed your intent but the 767 L1 door is electric but the other doors are manually opened unless the operator spec'd there aircraft with additional powered doors. Don't recall them being to heavy, but then I was younger in those days:) This was a corporate 767 so we got more opportunity to work the dooors than the average airline crew.
 
Apprentice
Posts: 777
Joined: Sat Jan 19, 2013 12:51 pm

Re: DC10 door operation

Mon Apr 29, 2019 1:55 am

Hello, Yes, there is a counter-balance helping to open the door in whichever method to open it.
Nevertheless, Door is heavy and it will need a serious help, electric, Pneumatic or hand help, to open the door.

Rgds
“An4; IL18; IL6; Tu5; D10; MD11; MD83; B32; B34: B37; B744; B748; B752; B763; B772; B773; B77W; A320; A332; A333; A342; A343.
"A NO" is a positive answer., "DON'T KNOW" is not. My Tutor (a wise man)
“CUBANA” 90 years Flying”

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