Print from Airliners.net discussion forum
http://www.airliners.net/aviation-forums/general_aviation/read.main/5724615/

Topic: Possible Design Change To B737MAX Cabin Door?
Username: YYCFlyer
Posted 2013-03-27 20:52:25 and read 15619 times.

Any chance Boeing is going to change or adjust the cabin doors, possibly add power assist when the door is armed?

I have tried to look for information on this and no luck.

Topic: Possible Design Change To B737MAX Cabin Door?
Username: rrobards2
Posted 2013-03-27 22:02:15 and read 15372 times.

I would also like to know what the doors will be like. As far as arming/disarming goes... Will it be more of a one step process or manually moving the girt bar back and forth?

Topic: Possible Design Change To B737MAX Cabin Door?
Username: YYCFlyer
Posted 2013-03-27 22:11:17 and read 15325 times.

It would be nice if Boeing could make the doors more like the 757.

Topic: Possible Design Change To B737MAX Cabin Door?
Username: questions
Posted 2013-03-27 22:18:38 and read 15262 times.

Some of us are not an agent de bord.  . Can you help us out and educate us as to what you're asking? Thanks!

Topic: Possible Design Change To B737MAX Cabin Door?
Username: AA737-823
Posted 2013-03-28 02:48:56 and read 14677 times.

As a 737 mechanic, I would LOVE it if they improved the door design! WHAT a pain in the.... neck.

BUT, I don't think it's likely. The door is still certificable via grandfather clause (as I understand it), and redesigning it or improving it would add a cost that Southwest Airlines is not willing to pay the bill for.

Incidentally, the doors on a 737 open very easily if you remove the slide pack... not that you get to do that very often.

Topic: Possible Design Change To B737MAX Cabin Door?
Username: debonair
Posted 2013-03-28 02:58:30 and read 14636 times.

It would be fantastic if Boeing would build A320-like-doors AND overwing-slides... The B737 doors are soo old fashioned!   

Just compare:

B737: http://www.youtube.com/watch?v=C9_BUR8rGtE
A320: http://www.youtube.com/watch?v=oqOyLKZApuc

Topic: RE: Possible Design Change To B737MAX Cabin Door?
Username: Cubsrule
Posted 2013-03-28 05:23:17 and read 14148 times.

Quoting debonair (Reply 5):
It would be fantastic if Boeing would build A320-like-doors AND overwing-slides...

Why in the world would Boeing add overwing slides when they are not necessary for certification or safe evacuation?

Topic: RE: Possible Design Change To B737MAX Cabin Door?
Username: queb
Posted 2013-03-28 05:34:21 and read 14096 times.

Quoting debonair (Reply 5):
It would be fantastic if Boeing would build A320-like-doors AND overwing-slides... The B737 doors are soo old fashioned!   

It would be fantastic if Airbus would build 737NG-like-overwing-doors... The a320 overwing doors are so old fashioned!

 

B737NG: http://youtu.be/6RULALwUizg
A320: http://youtu.be/RCFzEg-t_Bk

Topic: RE: Possible Design Change To B737MAX Cabin Door?
Username: 0NEWAIR0
Posted 2013-03-28 05:44:31 and read 14010 times.

Quoting debonair (Reply 5):
It would be fantastic if Boeing would build A320-like-doors AND overwing-slides... The B737 doors are soo old fashioned!

Those old fashioned doors are just one of several things that allow the 737 models to weigh anywhere from 3,000 lbs to 7,000 lbs less than their compeitors.

Topic: RE: Possible Design Change To B737MAX Cabin Door?
Username: queb
Posted 2013-03-28 05:50:58 and read 13958 times.

Quoting 0NEWAIR0 (Reply 8):
Those old fashioned doors are just one of several things that allow the 737 models to weigh anywhere from 3,000 lbs to 7,000 lbs less than their compeitors.

thanks to grandfather clauses...

Topic: RE: Possible Design Change To B737MAX Cabin Door?
Username: debonair
Posted 2013-03-28 06:06:58 and read 13886 times.

Quoting queb (Reply 7):
It would be fantastic if Airbus would build 737NG-like-overwing-doors...

TRUE! Let's put is this way - the A320neo will get B737NG overwing-doors and the B737max in return the A320 overwing slides and doors - and all are happy!

Topic: RE: Possible Design Change To B737MAX Cabin Door?
Username: Boeing717200
Posted 2013-03-28 06:11:52 and read 13853 times.

Quoting YYCFlyer (Thread starter):

Lift some weights. The door isn't that heavy.

Topic: RE: Possible Design Change To B737MAX Cabin Door?
Username: garynor
Posted 2013-03-28 06:34:37 and read 13594 times.

Uhm.. that A320 door doesn't look much like it's a plug type.. aren't all doors plugs to make them next to impossible to open when the cabin is pressurized?

Topic: RE: Possible Design Change To B737MAX Cabin Door?
Username: CrimsonNL
Posted 2013-03-28 06:37:02 and read 13562 times.

Quoting garynor (Reply 12):
Uhm.. that A320 door doesn't look much like it's a plug type.. aren't all doors plugs to make them next to impossible to open when the cabin is pressurized?


There's a plug type mechanism inside the door that can be seen from the cabin, that will slide inside the door when the handle bar is raised.

Martijn

Topic: RE: Possible Design Change To B737MAX Cabin Door?
Username: garynor
Posted 2013-03-28 06:47:44 and read 13353 times.

Quoting CrimsonNL (Reply 13):
There's a plug type mechanism inside the door that can be seen from the cabin, that will slide inside the door when the handle bar is raised.

That sounds more like a blocking mechanism, I thought doors had an additional plug design (thinner outer circumference) that would wedge them in place when inside pressure is applied. Of course, with lateral pressure on the blocks it will be hard to extract them and open the door, so it obviously works, I just need to adjust my perception of aircraft doors  

Topic: RE: Possible Design Change To B737MAX Cabin Door?
Username: B757forever
Posted 2013-03-28 07:13:43 and read 12930 times.

Quoting YYCFlyer (Reply 2):
It would be nice if Boeing could make the doors more like the 757.

Believe me, from a maintenance standpoint, you don't want this. The 757 has an over-complicated, power assisted, warmed over 727 door. Due to it's design it requires a large amount of routine maintenance. A fresh new design is what may be needed, but the grandfathered old design is what we will get...and like it!  

Topic: RE: Possible Design Change To B737MAX Cabin Door?
Username: milesrich
Posted 2013-03-28 09:11:31 and read 11502 times.

Isn't the 737 door very similar to that on the 707, 720, and 727? Designed almost 60 years ago?

Topic: RE: Possible Design Change To B737MAX Cabin Door?
Username: tb727
Posted 2013-03-28 09:16:41 and read 11414 times.

Quoting milesrich (Reply 16):
Isn't the 737 door very similar to that on the 707, 720, and 727? Designed almost 60 years ago?

From watching that video, it sure looks and operates the same as the 727 door.

Topic: RE: Possible Design Change To B737MAX Cabin Door?
Username: WNCrew
Posted 2013-03-28 09:25:52 and read 11286 times.

Quoting milesrich (Reply 16):

Isn't the 737 door very similar to that on the 707, 720, and 727? Designed almost 60 years ago?

It sure is! Antiquated, testy, difficult to operate and not even originally designed with a slide-pack!... you should see the ditching procedures for a 737 vs an airbus which can accommodate a slide/raft on the door. INSANE that it's still in production. It'll be 2020 and we'll be accepting delivery of a brand new aircraft where we STILL have to squat down and insert a nasty girt bar into the floor brackets, there's no central indicator for door status, no power assistance and still no provisions for a slide/raft.

Topic: RE: Possible Design Change To B737MAX Cabin Door?
Username: YYCFlyer
Posted 2013-03-28 11:03:34 and read 10204 times.

Quoting Boeing717200 (Reply 11):
Lift some weights. The door isn't that heavy.

I did't say anything about the weight of the door, just that power assist during an emergency would be nice.

Topic: RE: Possible Design Change To B737MAX Cabin Door?
Username: flyboy80
Posted 2013-03-28 11:41:18 and read 9749 times.

Yes, the 737 doors are of a unique design, simply old. I don't have too much trouble opening or closing them, infact I find it quite easy as they generate quite a bit of momentum.

I wonder why a 757 style can't be adopted, there may be space constraints with the mechanism that wouldn't fit around the current size area for the 737 door? Would be nice to not touch the nasty floor to ARM, and would be safer to have a auto-disarm feature when opened from the outside.

Topic: RE: Possible Design Change To B737MAX Cabin Door?
Username: DocLightning
Posted 2013-03-28 12:47:10 and read 9017 times.

Quoting B757forever (Reply 15):
but the grandfathered old design is what we will get...and like it!

You just hit the nail on the head. WHETHER YOU LIKE IT OR NOT, neither Boeing nor your airline care.

They care that the door works and is safe. They care about maintenance costs. They care about commonality with their other 737 types. They care about how much extra it would cost per airframe for Boeing to redesign the door. They care about how much it weighs (and how much fuel/payload that is going to cost them).

They do not care whether you enjoy opening it.

Topic: RE: Possible Design Change To B737MAX Cabin Door?
Username: Viscount724
Posted 2013-03-28 16:05:33 and read 7290 times.

Quoting DocLightning (Reply 21):
Quoting B757forever (Reply 15):
but the grandfathered old design is what we will get...and like it!

You just hit the nail on the head. WHETHER YOU LIKE IT OR NOT, neither Boeing nor your airline care.

They care that the door works and is safe. They care about maintenance costs. They care about commonality with their other 737 types. They care about how much extra it would cost per airframe for Boeing to redesign the door. They care about how much it weighs (and how much fuel/payload that is going to cost them).

They do not care whether you enjoy opening it.

Then why did they bother spending the money to re-design the overwing exits on the 737NG to be the hinged upward-opening type rather than the type that had to be thrown out of the aircraft as on earlier 737s?

Topic: RE: Possible Design Change To B737MAX Cabin Door?
Username: 1337Delta764
Posted 2013-03-28 16:19:00 and read 7143 times.

Considering that many airlines now operate 737s on overwater routes, one thing that I thought Boeing should offer as an option for the 737 MAX would be to offer slide rafts. However, this would require redesigning the doors similar to those on the 757 or A320.

Topic: RE: Possible Design Change To B737MAX Cabin Door?
Username: beachbum1970
Posted 2013-03-28 17:02:05 and read 6809 times.

Quoting WNCrew (Reply 18):
you should see the ditching procedures for a 737 vs an airbus which can accommodate a slide/raft on the door. INSANE that it's still in production
Quoting 1337Delta764 (Reply 23):
Considering that many airlines now operate 737s on overwater routes, one thing that I thought Boeing should offer as an option for the 737 MAX would be to offer slide rafts

I never knew that the 737 slides were NOT also life rafts. I wonder how the USAir flight that ditched in the Hudson would have turned out if it was a 737. Looking at photos from that ditching, with the plane floating in the water with a nose up attitude, could the flight attendants have swung open the 737 doors to their full locking position at that angle? And how would the F/As have gotten to the life rafts located in the ceiling with the passengers blocking the aisle scrambling to get out of the plane? Would they have asked the passengers to remain seated? A shame the 737 door design is "grandfathered". Makes you wonder if Boeing and the FAA really care about our safety at all. At the very least, the doors should be power assisted when armed and have an integrated slide and life raft.

Topic: RE: Possible Design Change To B737MAX Cabin Door?
Username: Barney Captain
Posted 2013-03-28 17:17:39 and read 7136 times.

Quoting queb (Reply 7):
It would be fantastic if Airbus would build 737NG-like-overwing-doors... The a320 overwing doors are so old fashioned!

 

B737NG: http://youtu.be/6RULALwUizg
A320: http://youtu.be/RCFzEg-t_Bk

Curiously, the video on the 737 shows exactly how it shouldn't be done. The handle should be grabbed underhand and from below - the overhand technique he used is a great way to break your wrist if you fail to let go in time.

Topic: RE: Possible Design Change To B737MAX Cabin Door?
Username: A36001
Posted 2013-03-28 17:33:40 and read 7026 times.

Quoting beachbum1970 (Reply 24):

Good Point regarding the US Airways and the Hudson. From the Youtube videos, I would rather the A320 opening sequence to the B737. Especially if it was the situation of the US Airways flight.

Could any Flight Attendant out there describe what it would of been like had that flight been operated by a 737 as opposed to the A320? Under exact same circumstances...  

Topic: RE: Possible Design Change To B737MAX Cabin Door?
Username: 1337Delta764
Posted 2013-03-28 17:49:42 and read 7018 times.

Quoting beachbum1970 (Reply 24):
I never knew that the 737 slides were NOT also life rafts. I wonder how the USAir flight that ditched in the Hudson would have turned out if it was a 737. Looking at photos from that ditching, with the plane floating in the water with a nose up attitude, could the flight attendants have swung open the 737 doors to their full locking position at that angle? And how would the F/As have gotten to the life rafts located in the ceiling with the passengers blocking the aisle scrambling to get out of the plane? Would they have asked the passengers to remain seated? A shame the 737 door design is "grandfathered". Makes you wonder if Boeing and the FAA really care about our safety.at all. At the very least, the doors should be power assisted when armed and have an integrated slide and life raft.

Note that on the A320 series, slide rafts are a customer option. The 757 is the only narrowbody that included them standard as far as I know. In fact, not all US Airways A32x are equipped with them (the A320s that DO have them are designated as EOW). Luckily US 1549 was on one of the EOW aircraft.

[Edited 2013-03-28 17:59:04]

Topic: RE: Possible Design Change To B737MAX Cabin Door?
Username: jetmarc
Posted 2013-03-28 18:43:28 and read 6492 times.

I've always loved this video... shows how you need to use a little muscle and momentum to close the B737 doors... http://youtu.be/cjgkVz9GOKk

Topic: RE: Possible Design Change To B737MAX Cabin Door?
Username: YYCFlyer
Posted 2013-03-28 18:56:02 and read 6394 times.

Quoting A36001 (Reply 26):
Could any Flight Attendant out there describe what it would of been like had that flight been operated by a 737 as opposed to the A320? Under exact same circumstances...  

According to the Boeing Flight Attendant Manual for the 737 family the forward slides could be deployed in a ditching and used as a flotation device, my understanding all sides on the 737 are equipped with a ditching release handle. The procedure to deploy the slide in a ditching will depend on the airline. I know in Canada we have operators of the 737NGs that both instruct their Flight Attendants to deploy the slide in the water to use as a flotation devise and some that require them to disarm their door prior to opening in a ditching.

In the event of US Airways 1549 if the aircraft was a 737 or an A320 not equipped with a slide raft, it in my opinion could have turned out some what different. The passengers who evacuated out the forward doors would have had to jump into the water with their life jackets and hold onto the deployed slide (if the airline procedure is to deploy it) and place any injured or children on top of the slide. Resulting in I'm sure a large number of passengers experiencing hypothermia from the freeing water. The 737s that have been approved for ETOPs flying will be equipped with rafts that would have to be pulled out from storage and deployed resulting in a delay of evacuation or if the procedure is to deploy the raft after the passengers have evacuated then leaving the passengers in the potentially freezing water until the Flight Attendants were able to deploy them.

Just my 5cents ... (we are no longer using the penny in Canada)

Topic: RE: Possible Design Change To B737MAX Cabin Door?
Username: YYCFlyer
Posted 2013-03-28 19:05:01 and read 6284 times.

Quoting debonair (Reply 5):
It would be fantastic if Boeing would build A320-like-doors AND overwing-slides... The B737 doors are soo old fashioned!  

The distance of the 737NGs wings from the ground doesn't require a slide to be built into the wing such as the Airbus 320 family.

Topic: RE: Possible Design Change To B737MAX Cabin Door?
Username: jetmech
Posted 2013-03-28 19:33:44 and read 6064 times.

Quoting Viscount724 (Reply 22):
Then why did they bother spending the money to re-design the overwing exits on the 737NG to be the hinged upward-opening type rather than the type that had to be thrown out of the aircraft as on earlier 737s?

Wasn't the redesign due to the EASA was not happy with the old design? The physical effort to pull, lift and throw the old exit is somewhat more than that required to open the hinged design, which is a safety concern. The fact that operating the new door is more "enjoyable" just happens to be a nice side benefit.

The NG and longer fuselage variants of the 737 probably required much re-design of the existing overwing fuselage area of the structure, so maybe this gave more justification for the EASA to demand an update on the emergency exit design?

Regards, JetMech

Topic: RE: Possible Design Change To B737MAX Cabin Door?
Username: ADent
Posted 2013-03-28 19:40:49 and read 5974 times.

Quoting garynor (Reply 12):
aren't all doors plugs to make them next to impossible to open when the cabin is pressurized?

The 737NG over wing exits are locked with an electric solenoid, not air pressure like most doors.

Topic: RE: Possible Design Change To B737MAX Cabin Door?
Username: DocLightning
Posted 2013-03-28 19:52:36 and read 5881 times.

Quoting Viscount724 (Reply 22):
Then why did they bother spending the money to re-design the overwing exits on the 737NG to be the hinged upward-opening type rather than the type that had to be thrown out of the aircraft as on earlier 737s?

I would wager it had something to do with safety, but I guarantee it wasn't about whether the crew liked opening them.

Quoting ADent (Reply 32):
The 737NG over wing exits are locked with an electric solenoid, not air pressure like most doors.

Does that mean one could theoretically open in flight? I don't like that...

Topic: RE: Possible Design Change To B737MAX Cabin Door?
Username: YYCFlyer
Posted 2013-03-28 20:19:41 and read 5669 times.

Quoting DocLightning (Reply 33):
Does that mean one could theoretically open in flight? I don't like that...

Once one of the engines have started a locking system goes into place and the window exit can't be opened, even if still on the ground and not moving.

Topic: RE: Possible Design Change To B737MAX Cabin Door?
Username: jetmech
Posted 2013-03-28 20:53:05 and read 5455 times.

Quoting ADent (Reply 32):

The newer over-wing exits of the 737NG strike me as miniature variations of the B777 passenger door design, in that it appears that the doors slides up to disengaged the load fittings before swinging up. This picture appears to suggest that the solenoid feature is perhaps there to prevent inadvertent opening on the ground only (i.e. when no differential pressure is present)?.

http://www.sjap.nl/flightlock2.JPG

http://www.sjap.nl/overwing-emergenc...ght-on-including-video-737-678900/

Quoting DocLightning (Reply 33):
Does that mean one could theoretically open in flight? I don't like that...

Boeing has a clever design feature for passenger and cargo doors, in that the locking mechanism is usually connected to a small, separate hinged panel on the door itself. When the aircraft is pressurised, the differential acts on this small, hinged panel and provides positive force to keep the locking mechanism in the closed position.

This feature also prevents proper pressurisation of the aircraft if the locking mechanism is not properly closed. The following photo is, I believe, a 737-500 over-wing exit, and you can see how the external push in panel forms the feature discussed in the previous paragraph,

http://www.luxurylaunches.com/wp-con.../12/BA-crash-survival-course-5.jpg

I suspect the 737NG over-wing exits would have a similar feature, and if so, even if the solenoid is faulty, one must be able to pull against the differential acting on the small, hinged panel in order to open the door in flight. Assuming the panel is 7" by 4" with a differential pressure of 8.5 psi, a direct pull (assuming no mechanical advantage) of 238 pounds would be required to dislodge the panel.

If one is strong enough to do this, then the door could theoretically be opened in flight.

Regards, JetMech

Topic: RE: Possible Design Change To B737MAX Cabin Door?
Username: francoflier
Posted 2013-03-28 21:04:10 and read 5370 times.

Quoting queb (Reply 7):
The a320 overwing doors are so old fashioned!

True. It's a wonder certifying bodies still allow these removable doors. There is so much that can go wrong when you have a panicked passenger try to physically remove a large aluminium panel out of its frame and through it out of the way...

Quoting WNCrew (Reply 18):
ew aircraft where we STILL have to squat down and insert a nasty girt bar into the floor brackets, there's no central indicator for door status, no power assistance and still no provisions for a slide/raft.

Is the slide pack attached to the door on the 737? If yes, how hard would it be to link the girt bar to the arm/disarm lever like on the 747 (and maybe 757, which I don't know)?

Topic: RE: Possible Design Change To B737MAX Cabin Door?
Username: yeelep
Posted 2013-03-29 10:31:52 and read 4792 times.

Quoting jetmarc (Reply 28):
I've always loved this video... shows how you need to use a little muscle and momentum to close the B737 doors... http://youtu.be/cjgkVz9GOKk

That door is out of rig. The F/A is relying on the momentum of the door to engage the forward latch rollers.

Quoting ADent (Reply 32):
The 737NG over wing exits are locked with an electric solenoid, not air pressure like most doors.
Quoting DocLightning (Reply 33):
Quoting ADent (Reply 32):
The 737NG over wing exits are locked with an electric solenoid, not air pressure like most doors.

Does that mean one could theoretically open in flight? I don't like that...

Yes and no. The solenoid is locked when these conditions are met. Three or more of the entry/service doors are closed, Either engine is running, Air ground logic is in the AIR MODE or both the left and right
thrust levers are advanced more than 53 degrees. When the cabin is pressurized the door stop fittings are driven outward against the fuselage stop fittings. It is no different than the entry/ service doors.

Quoting YYCFlyer (Reply 34):
Once one of the engines have started a locking system goes into place and the window exit can't be opened, even if still on the ground and not moving.

Not true.

Quoting jetmech (Reply 35):
Boeing has a clever design feature for passenger and cargo doors, in that the locking mechanism is usually connected to a small, separate hinged panel on the door itself.
Quoting jetmech (Reply 35):
I suspect the 737NG over-wing exits would have a similar feature, and if so, even if the solenoid is faulty, one must be able to pull against the differential acting on the small, hinged panel in order to open the door in flight.

They do have that feature on the NG.

Quoting jetmech (Reply 35):
If one is strong enough to do this, then the door could theoretically be opened in flight.

You would also have to rotate the opening mechanism against the differential pressure acting against the entire door. nobody is that strong.

Quoting francoflier (Reply 36):
Is the slide pack attached to the door on the 737?

Yes.

Topic: RE: Possible Design Change To B737MAX Cabin Door?
Username: tardis
Posted 2013-03-29 11:40:36 and read 4643 times.

Quoting Viscount724 (Reply 22):

Then why did they bother spending the money to re-design the overwing exits on the 737NG to be the hinged upward-opening type rather than the type that had to be thrown out of the aircraft as on earlier 737s?

It was a weight issue, the new doors weigh more than the "classic" or "initial" over wing exits, so they were redesigned to hinge out and up. IMO, much safer that way too.

Topic: RE: Possible Design Change To B737MAX Cabin Door?
Username: Viscount724
Posted 2013-03-29 14:20:41 and read 4440 times.

Quoting DocLightning (Reply 33):
Quoting Viscount724 (Reply 22):
Then why did they bother spending the money to re-design the overwing exits on the 737NG to be the hinged upward-opening type rather than the type that had to be thrown out of the aircraft as on earlier 737s?

I would wager it had something to do with safety, but I guarantee it wasn't about whether the crew liked opening them.

As a sidenote, I believe a primary reason for replacing the original hinged outward-opening doors on the 700-series Vickers Viscount with the "Airbus" type of doors that slide sideways against the fuselage on the 800-series was to make opening and closing the doors easier in strong winds.

-700 series:


View Large View Medium
Click here for bigger photo!

Photo © John Kelley
View Large View Medium
Click here for bigger photo!

Photo © John F. Ciesla




-800 series:


View Large View Medium
Click here for bigger photo!

Photo © Mel Lawrence
View Large View Medium
Click here for bigger photo!

Photo © Lars Söderström

Topic: RE: Possible Design Change To B737MAX Cabin Door?
Username: jetmech
Posted 2013-03-30 23:14:13 and read 3861 times.

Quoting yeelep (Reply 37):
You would also have to rotate the opening mechanism against the differential pressure acting against the entire door. nobody is that strong.

In the older, unhinged overwing exits, once the handle has been pulled, one would then need to overcome the remaining differential acting on the door in order to pull it off the stops for removal. As you say, this force would be much greater than that needed to overcome the handle / vent panel force.

The newer design of overwing exit however, mainly features an upward sliding motion to disengage the load fittings.

http://www.google.com/patents/US5031863

On the whole, the door does move inward slightly to clear the stops and allow opening, but this movement appears to be assisted by significant mechanical advantage, which would make the effort required somewhat less than the direct pull required by the older design.

Regards, JetMech

Topic: RE: Possible Design Change To B737MAX Cabin Door?
Username: Crosswind
Posted 2013-03-31 04:50:21 and read 3644 times.

Quoting queb (Reply 7):
It would be fantastic if Airbus would build 737NG-like-overwing-doors... The a320 overwing doors are so old fashioned!

They are, but they meet the current requirements for the minimum size of a type-III exit, unfortunately the 737NG overwing exits didn't.

Quoting Viscount724 (Reply 22):
Then why did they bother spending the money to re-design the overwing exits on the 737NG to be the hinged upward-opening type rather than the type that had to be thrown out of the aircraft as on earlier 737s?

They had to, the JAA were not going to certify the aircraft for the max seating capacity otherwise! (See below)

Quoting tardis (Reply 38):
It was a weight issue, the new doors weigh more than the "classic" or "initial" over wing exits, so they were redesigned to hinge out and up. IMO, much safer that way too.

Nothing to do with the weight of the door, I'd guess they weigh less than those of an A320. It was down to the size of the door, which didn't meet the minimum size for a type-III exit at the time (and the A320 did).

This change happened very late in the game - well after the aircraft had first flown - as the JAA had refused grandfather rights to carry over the previous exits. It was far too late to install larger doors, so the solution was the quick opening exits - which although smaller would be ready for evacuation 10s quicker than those on the A320, providing an equivalent level of safety.

Read the full Flight International article below, and check the date to see how late in the game this was solved! The 737-700 was well into it's flight testing and the first 737-800 had already been rolled out and flew later that month.
http://www.flightglobal.com/pdfarchive/view/1997/1997%20-%201786.html

Regards
CROSSWIND

Topic: RE: Possible Design Change To B737MAX Cabin Door?
Username: HiFlyerAS
Posted 2013-03-31 08:34:56 and read 3457 times.

I was fortunate enough to be given a tour of the Boeing Renton 737 factory last week. I just happened to meet a "door inspector" and, knowing this thread was happening, asked him if a decision had been made about the MAX doors. He said that Boeing had elicited suggestions from his team but he was doubtful that any change would be made to the current design. I asked if it had originated with the 707 and he believed it had. For what it's worth  

Topic: RE: Possible Design Change To B737MAX Cabin Door?
Username: jetmech
Posted 2013-03-31 22:53:30 and read 3109 times.

Quoting Crosswind (Reply 41):
Read the full Flight International article below, and check the date to see how late in the game this was solved! The 737-700 was well into it's flight testing and the first 737-800 had already been rolled out and flew later that month.
http://www.flightglobal.com/pdfarchi....html

Going by the article, the most relevant patent with respect to the 737 NG over-wing exits is the following;

http://www.google.com/patents/US5931415

In this case, the door slides downward to disengage the load fittings. Interestingly, there appears to be little to no inward movement of the door, if anything, any remaining cabin pressure would appear to assist the outward movement of the bottom of the door.

Regards, JetMech


The messages in this discussion express the views of the author of the message, not necessarily the views of Airliners.net or any entity associated with Airliners.net.

Copyright © Lundgren Aerospace. All rights reserved.
http://www.airliners.net/