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crownvic
Topic Author
Posts: 2801
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Door Latch Question

Thu Mar 11, 2021 4:15 am

I guess its no big deal...3:55 into video door latch

https://www.youtube.com/watch?v=X11SFdQqHaI
 
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Starlionblue
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Re: Door Latch Question

Thu Mar 11, 2021 4:17 am

crownvic wrote:
I guess its no big deal...3:55 into video door latch

https://www.youtube.com/watch?v=X11SFdQqHaI


Ha.

Kind of a big deal if you want to go flying. I don't know the 737 but I imagine you'd get a warning in the cockpit if the door wasn't properly latched.
"There are no stupid questions, but there are a lot of inquisitive idiots." - John Ringo
 
Lukas757
Posts: 67
Joined: Sun May 08, 2016 11:59 pm

Re: Door Latch Question

Thu Mar 11, 2021 4:53 am

There is a warning light for every door on the 737 if not properly latched.
It will illuminate together with the master caution light.

For reference:
http://www.b737.org.uk/aircraft_general.htm#Doors
 
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fr8mech
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Re: Door Latch Question

Thu Mar 11, 2021 11:43 am

But, that door is latched. The handle just wasn’t stowed properly. Sloppy, but still locked.
When seconds count, the police are minutes away, or may not come at all.
It’s hard to win an argument with a smart person, but it’s damn near impossible to win an argument with a stupid person. ~B. Murray
Ego Bibere Capulus, Ut Aliis Sit Vivere
 
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Starlionblue
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Re: Door Latch Question

Thu Mar 11, 2021 11:44 am

fr8mech wrote:
But, that door is latched. The handle just wasn’t stowed properly. Sloppy, but still locked.


Aaaah.

But isn't that just bad handle design? ;)
"There are no stupid questions, but there are a lot of inquisitive idiots." - John Ringo
 
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Horstroad
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Re: Door Latch Question

Thu Mar 11, 2021 11:53 am

The exterior door handle is somewhat independent from the interior one. It has to be as you want to be able to operate the door from the inside without the outer handle moving out of its recess. The exterior handle engages the cam plate of the handle mechanism with a spline when it is pulled out of the recess.
The door seems to be latched, as the upper and lower gates (which are connected to the latch torque tube) are closed (and the aircraft is moving, so probably no door warning is active).
I assume something in the handle mechanism that connects the exterior handle to the rest is broken. Maybe the spline or shaft sheared off.

edit:
fr8mech wrote:
The handle just wasn’t stowed properly.

Can the exterior handle engage (or disengage) the handle mechanism in any position? I'm not familiar with the 737... but the exterior handle of the 777 can only engage the handle mechanism when it matches the position of the inner handle and it only disengages when the door is latched (which means the handle is in the correct position over the recess.)
 
Flow2706
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Re: Door Latch Question

Thu Mar 11, 2021 12:05 pm

When I was a ramp agent (before my first pilot job) we were dispatching 737s as well. It was a very common occurrence and was usually spotted by the ramp agent during his walk around before push back. I don't think there is an indication in the cockpit, so most of the time we would just inform the crew, so they could fix the issue.
A friend of mine used to work as cabin crew on 737s. He said he once had a loud sound from one door. Initially they though there was an issue with the door seal, but it turned out that the sound was caused by the unstowed door handle.
 
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fr8mech
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Re: Door Latch Question

Thu Mar 11, 2021 12:43 pm

Horstroad wrote:
I assume something in the handle mechanism that connects the exterior handle to the rest is broken. Maybe the spline or shaft sheared off


My assumption is the door is just fine.

Horstroad wrote:
Can the exterior handle engage (or disengage) the handle mechanism in any position? I'm not familiar with the 737... but the exterior handle of the 777 can only engage the handle mechanism when it matches the position of the inner handle and it only disengages when the door is latched (which means the handle is in the correct position over the recess.)


Disclaimer: I haven’t dealt with a B737, but as I recall the door is similar, if not the same as a B727. When the door is closed and latched, the handle would fit directly into the recess. Allowing it to retract...or pushing it...into the recess disengages the handle from the inner mechanism.

To unlock the door, you’d pull the handle out of the recess...about 2-3 inches, and turn the handle. The gates retract and the door moves in a little. Continue turning, and the door opens. Stow the handle, and swing the door open the rest if the way.

Can you engage the handle anywhere independent of the mechanism position? No. The outer handle has to match the position of the inner door mechanism.

Starlionblue wrote:
But isn't that just bad handle design?


Maybe, maybe not. You want to be able to move the inner handle independently of the outer handle, and this is a simple design. I’ve dealt with the A300 door handle design, and found that the disengage mechanism is a little more complicated. Maybe that’s a function of the way the handle moves...vertical vs. rotary...maybe it’s just the way Airbus tends to over-engineer some things.
When seconds count, the police are minutes away, or may not come at all.
It’s hard to win an argument with a smart person, but it’s damn near impossible to win an argument with a stupid person. ~B. Murray
Ego Bibere Capulus, Ut Aliis Sit Vivere
 
Thrusty69
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Re: Door Latch Question

Thu Mar 11, 2021 1:54 pm

The handle is free to rotate 360° when pulled partially out. When pulled fully out the splines engage the door mechanism and as the handle is rotated the door opens. So the only concern here would be: Can the airflow in flight be enough to pull the handle fully out and engage the door mechanism? Prolly not. The airflow would have a better chance of pushing the handle back into its recess. Also the handle is spring loaded to pull its self against the door.
 
DualQual
Posts: 737
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Re: Door Latch Question

Thu Mar 11, 2021 4:36 pm

Thrusty69 wrote:
The handle is free to rotate 360° when pulled partially out. When pulled fully out the splines engage the door mechanism and as the handle is rotated the door opens. So the only concern here would be: Can the airflow in flight be enough to pull the handle fully out and engage the door mechanism? Prolly not. The airflow would have a better chance of pushing the handle back into its recess. Also the handle is spring loaded to pull its self against the door.


Even if the airflow could pull the handle out (the chances of that are close enough to 0 to call it 0) the door still has to open inward slightly. With the airplane pressurized it ain’t gonna happen. No different from all the “can the door be opened inflight” questions.
There's no known cure for stupid
 
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DL_Mech
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Re: Door Latch Question

Fri Mar 12, 2021 12:40 am

This happened when the first 737-700 was delivered to DL. The R1 handle flew like this from Seattle to Atlanta. There was a long forum discussion about it in 2008 (could not find it in the search engine).

http://www.jetphotos.com/photo/6320654
This plane is built to withstand anything... except a bad pilot.

Former AMT on A220,A310,A319/20/21,A330,A350,B707,B717,B727,B737,B747,B757,B767,B777,DC-9,DC-10,L-1011,
MD-80/90,MD-11
 
Redbellyguppy
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Re: Door Latch Question

Fri Mar 12, 2021 4:27 am

Air loads move the handle to an aerodynamically neutral position. There won’t be any indication in the cockpit if the door is otherwise properly closed. Thee won’t be unusual noise or pressurization issues. An exterior handle is not a no-go item for that operator.
 
DarQuiet
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Re: Door Latch Question

Sun Mar 14, 2021 3:56 pm

I have so many questions... Was the aircraft released under MEL for this case? Were there pax reduction nearby that door? There must have been at least some ground personnel who witnessed the odd position of the latch upon closure of the door. What/how is the fix upon arrival?

"Assuming" the latch mechanism from the cabin side looks normal and cockpit did not have any door warning, why would Boeing let their planes look unsafe and expect people to shrug it off just because?
 
Tristarsteve
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Re: Door Latch Question

Sun Mar 14, 2021 4:35 pm

No need for MEL, nothing is broken. The door handle on the inside is normal, and there is no warning in the cockpit.
This happens all the time on B737 and B757 (different system, but same problem.) Usually spotted by the ground crew, and fixed from the ground by pushing it with a long broomstick! But if at is on a catering door, I always called the catering truck back to fix it, might make them do it right nest time. The only problem will be a bit more noise in flight.
 
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fr8mech
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Re: Door Latch Question

Sun Mar 14, 2021 7:57 pm

DarQuiet wrote:
I have so many questions... Was the aircraft released under MEL for this case?


There is nothing wrong with this door. This is just a sloppy dispatch. The person who pulled the jetway should have faired the handle.

Why did Boeing design it this way? Because it’s a simple design.
When seconds count, the police are minutes away, or may not come at all.
It’s hard to win an argument with a smart person, but it’s damn near impossible to win an argument with a stupid person. ~B. Murray
Ego Bibere Capulus, Ut Aliis Sit Vivere
 
nws2002
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Re: Door Latch Question

Wed Mar 17, 2021 12:22 am

I work for an airline that only has 737s and this happens occasionally. Like others have said, the door is closed and latched. There is no danger of it opening. Either the gate agent failed to notice when the door was closed or the spring that hold the handle in the recess is loose.
 
DarQuiet
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Re: Door Latch Question

Thu Mar 18, 2021 8:18 am

Interesting! Seeing the responses of most, it is:

1. A known issue but no cause for alarm.
2. It is seen to have a low risk/impact even with seldom occurrence.
3. No permanent fix available nor planned terminating action in the near future (linked to item 1 and 2).

Had a fun read to learn a thing or two about Boeing.

Thank you A.NETizens and to OP!
 
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fr8mech
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Re: Door Latch Question

Thu Mar 18, 2021 9:26 am

DarQuiet wrote:
Interesting! Seeing the responses of most, it is:

1. A known issue but no cause for alarm.
2. It is seen to have a low risk/impact even with seldom occurrence.
3. No permanent fix available nor planned terminating action in the near future (linked to item 1 and 2).

Had a fun read to learn a thing or two about Boeing.

Thank you A.NETizens and to OP!


Your post seems to indicate that you think there is something wrong with the door and Boeing doesn't want to fix the issue. You're wrong. The door is not faulty.
When seconds count, the police are minutes away, or may not come at all.
It’s hard to win an argument with a smart person, but it’s damn near impossible to win an argument with a stupid person. ~B. Murray
Ego Bibere Capulus, Ut Aliis Sit Vivere
 
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SAAFNAV
Posts: 630
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Re: Door Latch Question

Thu Mar 18, 2021 12:07 pm

DarQuiet wrote:
Interesting! Seeing the responses of most, it is:

1. A known issue but no cause for alarm.
2. It is seen to have a low risk/impact even with seldom occurrence.
3. No permanent fix available nor planned terminating action in the near future (linked to item 1 and 2).

Had a fun read to learn a thing or two about Boeing.

Thank you A.NETizens and to OP!


As the poster below you said, it seems you are fixed upon believing it is an issue.

The mechanism, as described earlier, has got separate actuation mechanism, one for inside, one for outside. In order for it to work, there must be a disconnect/void/discontinuance between the two mechanisms.

Think of it like the door openers on certain cars - if the door is locked, the inside handle can pull, without it 1) opening the door and 2) moving the outside handle. Conversely, you can pull the outside handle, but it is disconnected from the inside.
Now, if the spring on the outside handle pulling it against the door was worn out, the handle might flap around a bit. However, that does not mean the opening mechanism is faulty.
Also not an indictment of the manufacturer of the car.
ex L-382G Loadmaster, ex C-130B Navigator, Möchtegern Flugzeugführer

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