CRJ Door / Pressurization Question
07-05-2008, 07:20 AM
#1
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CRJ Door / Pressurization Question
Hey guys…. So I have a question… which has somewhat been explained to me, but I’m still a little fuzzy!
I’ve been told that it’s next to impossible to open a cabin door in-flight, due to the pressure differential. Now this makes perfect sense on the over-wing exits (which are plug type); however, the MCD (and possibly the service door?) on the CRJ are not plug type – they don’t have to come back in before going out. (Or do they, and I just never noticed?)
But if they’re not plug type, and they do just open straight out… then theoretically the only thing holding them closed are the locking pins?!
So yea…. I’m probably missing something! Any of you guys that fly the CRJ want to offer an explanation?
Thanks! =)
I’ve been told that it’s next to impossible to open a cabin door in-flight, due to the pressure differential. Now this makes perfect sense on the over-wing exits (which are plug type); however, the MCD (and possibly the service door?) on the CRJ are not plug type – they don’t have to come back in before going out. (Or do they, and I just never noticed?)
But if they’re not plug type, and they do just open straight out… then theoretically the only thing holding them closed are the locking pins?!
So yea…. I’m probably missing something! Any of you guys that fly the CRJ want to offer an explanation?
Thanks! =)
07-05-2008, 07:33 AM
#2
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Joined APC: Jan 2006
Position: Engines Turn Or People Swim
Posts: 39,293
The CRJ main cabin door is NOT a plug type door. It does NOT have to open inward first.
The only thing holding it in place is the pins and cams.
I am not aware of any pressure-based safety interlocks, so I would assume that if you pulled the handle open, the cabin door would open, and probably depart the airplane, possibly entering (and destroying) the left engine.
You would follow the cabin door into the engine in about 25 milliseconds.
The only thing holding it in place is the pins and cams.
I am not aware of any pressure-based safety interlocks, so I would assume that if you pulled the handle open, the cabin door would open, and probably depart the airplane, possibly entering (and destroying) the left engine.
You would follow the cabin door into the engine in about 25 milliseconds.
07-05-2008, 07:58 AM
#5
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Posts: 633
I've wondered this myself.
Wouldn't the airflow about the fuselage "hold" the door closed? I've had a Seminole door open in flight and it is impossible to close in the air due to it not being a completely airtight vessel. So, since the CRJ is pressurized there would be nothing pushing the door open aside from the person opening the door. And I doubt that person is strong enough to overcome the outside pressure holding the door closed.
Maybe?
Wouldn't the airflow about the fuselage "hold" the door closed? I've had a Seminole door open in flight and it is impossible to close in the air due to it not being a completely airtight vessel. So, since the CRJ is pressurized there would be nothing pushing the door open aside from the person opening the door. And I doubt that person is strong enough to overcome the outside pressure holding the door closed.
Maybe?
07-05-2008, 08:03 AM
#6
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Originally Posted by cyrcadian
I've wondered this myself.
Wouldn't the airflow about the fuselage "hold" the door closed? I've had a Seminole door open in flight and it is impossible to close in the air due to it not being a completely airtight vessel. So, since the CRJ is pressurized there would be nothing pushing the door open aside from the person opening the door. And I doubt that person is strong enough to overcome the outside pressure holding the door closed.
Maybe?
Wouldn't the airflow about the fuselage "hold" the door closed? I've had a Seminole door open in flight and it is impossible to close in the air due to it not being a completely airtight vessel. So, since the CRJ is pressurized there would be nothing pushing the door open aside from the person opening the door. And I doubt that person is strong enough to overcome the outside pressure holding the door closed.
Maybe?
Maybe if the cabin was depressurized first. If the cabin is pressurized...
Lets say 8 psi...
The door is about 3ft x 6 ft (approx)...
3 x 6= 18 Square feet
Convert to inches: 18 x 144 = 2592 square inches
8 x 2592 = 20,736 pounds (over ten TONS)!
My bet is the door would pop right open...
07-05-2008, 08:08 AM
#7
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Joined APC: Feb 2007
Position: FO
Posts: 3,032
Originally Posted by rickair7777
Maybe if the cabin was depressurized first. If the cabin is pressurized...
Lets say 8 psi...
The door is about 3ft x 6 ft (approx)...
3 x 6= 18 Square feet
Convert to inches: 18 x 144 = 2592 square inches
8 x 2592 = 20,736 pounds (over ten TONS)!
My bet is the door would pop right open...
Lets say 8 psi...
The door is about 3ft x 6 ft (approx)...
3 x 6= 18 Square feet
Convert to inches: 18 x 144 = 2592 square inches
8 x 2592 = 20,736 pounds (over ten TONS)!
My bet is the door would pop right open...
07-05-2008, 08:15 AM
#8
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Joined APC: Jan 2008
Position: CRJ
Posts: 76
Originally Posted by rickair7777
Maybe if the cabin was depressurized first. If the cabin is pressurized...
Lets say 8 psi...
The door is about 3ft x 6 ft (approx)...
3 x 6= 18 Square feet
Convert to inches: 18 x 144 = 2592 square inches
8 x 2592 = 20,736 pounds (over ten TONS)!
My bet is the door would pop right open...
Lets say 8 psi...
The door is about 3ft x 6 ft (approx)...
3 x 6= 18 Square feet
Convert to inches: 18 x 144 = 2592 square inches
8 x 2592 = 20,736 pounds (over ten TONS)!
My bet is the door would pop right open...
07-05-2008, 08:20 AM
#9
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Joined APC: Jul 2006
Position: Popsicle Logic
Posts: 633
Originally Posted by BlueMoon
That is the same amount of pressure on the pins, I'm going to say it would be near impossible to rotate the cams with that much pressure on it...the handle would snap first.
07-05-2008, 08:23 AM
#10
Gets Weekends Off
Joined APC: Jan 2007
Position: CRJ CA
Posts: 117
Don't forget the MCD and the emerg. exits on the CRJ have pressure panels that open when you pull the handle. The MCD handle has two positions when you pull up. The first opens the panel and releases the pressure. The second click actually releases the door.
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