Mr AirNZ
Topic Author
Posts: 857
Joined: Sat Feb 02, 2002 10:24 am

A320 And 737NG Emergency Exits!

Mon Sep 30, 2002 4:22 pm

On the 737NG the overwing emergency exits pop upwards but stay fixed to the aircraft but as I understand the overwing exits on the A320 are 'free' (like plugs). Why is this. As far as I know the FAA or JAA made boeing make the 737NG's exits like this. Why is the A320 different?

http://www.boeing.com/commercial/aeromagazine/aero_08/human_fig04.html
 
fritzi
Posts: 2598
Joined: Sat Jun 30, 2001 2:34 am

RE: A320 And 737NG Emergency Exits!

Mon Sep 30, 2002 5:04 pm

Doesn't the FAA only govern over US airlines?
 
Duncan
Posts: 134
Joined: Mon Apr 08, 2002 1:14 am

RE: A320 And 737NG Emergency Exits!

Tue Oct 01, 2002 1:18 am

The rules are (basically) the same regardless of where the A/C are made, aircraft also have to comply with the regulations of the airworthiness authorities of where the aircraft is operated. So both the A320 and 737NG must comply with FAA and JAA/CAA regulations. The fact that the rules are different is that when the A320 series was type certified back in 1988 (FAA Type Certificate A28NM) this rule didn't exist. It was only in the mid 90's or so that the certification rules for Pax-to-exit-door-ratio changed, requiring that the overwing hatches be changed to outward opening hinged doors for the 737NG. Since the A320 is type certified before this came into effect, it does not need to comply with this requirement (just as the 737 classics do not either). The FAR's change constantly and it would be impractical to require the retroactive type certification of aircraft in service to accommodate all the changes to the FAR's.

DD
 
Mr AirNZ
Topic Author
Posts: 857
Joined: Sat Feb 02, 2002 10:24 am

RE: A320 And 737NG Emergency Exits!

Tue Oct 01, 2002 8:09 am

Thanks for clearing that up for me  Big thumbs up!
 
techspec
Posts: 71
Joined: Sun Sep 16, 2001 2:40 am

RE: A320 And 737NG Emergency Exits!

Tue Oct 01, 2002 8:49 am

Regarding the exits on the Next Gen's.

Where is the logic in this design mandated by the FAR's? A design that worked very well on the original design of the aircraft and was used through the Classics (-300, -400,-500). Very simple and easy to maintain.

The doors on the Next Gen's are an engineering marvel but not easy to maintain. The MEL procedures are virtually impossible to comply with.

Any comments?
 
Murf
Posts: 143
Joined: Mon Nov 06, 2000 11:47 am

RE: A320 And 737NG Emergency Exits!

Tue Oct 01, 2002 10:28 am

How is the next gen Exit opened to the up position?

Is it pushed up and locked open by the passenger or is there some kind of assisting component/mechanism?

Murf
 
techspec
Posts: 71
Joined: Sun Sep 16, 2001 2:40 am

RE: A320 And 737NG Emergency Exits!

Tue Oct 01, 2002 11:44 am

There is a counterbalance assembly that opens and keeps the door open.
There are hydraulic snubbers that maintain a set velocity when it opens and keeps it open.

A locking mechanism is activated during the take-off roll, basically a plunger engages the torque tube mechanism preventing rotation.
 
Duncan
Posts: 134
Joined: Mon Apr 08, 2002 1:14 am

RE: A320 And 737NG Emergency Exits!

Wed Oct 02, 2002 3:43 am

Techspec,

The redesign is not madated by the FAR, it's a UKCAA requirement (though I cannot prove this, it's just what we knew when we were retrofitting the first 737NG's during type certification at Boeing). Yes, the older classic design is a good solid deisgn, nothing wrong with it, but after the investigation of an aircraft fire at Manchester where a 737 (I think a BA -400) was engulfed in flames and evacuation time was the difference between life and death for a lot of people. The AAIB (Air Accident Investigation Branch) recommended to the UKCAA that better egress be a requirement, hence the change.

Existing designs are satisfactory, but there is always room for improvememt and lessons to be learned from other's tragic losses. This is why air travel is the safest form of transport. But we should never cease to strive for zero fatalities.

DD
 
Chiuaua
Posts: 102
Joined: Sun Apr 16, 2000 9:31 pm

RE: A320 And 737NG Emergency Exits!

Wed Oct 02, 2002 7:08 am

There are injuries known due to the new emergency exits. When the first 737NG's were produced, several Boeing mechanics were injured due to very quick opening from the doors (when they were opening them from the outside). Injuries varied from serious injury to fingers (at least some were broken, I can't say if people have got there fingers chopped of by it) and also getting smashed by the door when it opened. So it might save lives during an evacuation, but what will the rate of maintenance injuries be compared to the saving of lives (please do not think that I put personal health above life).

Greetz, Chiuaua.
 
Duncan
Posts: 134
Joined: Mon Apr 08, 2002 1:14 am

RE: A320 And 737NG Emergency Exits!

Wed Oct 02, 2002 11:48 pm

True, there were initial teething Mx problems with the new doors at Boeing. I know of one instance where some lost a finger, or at least part of, from getting their hand in the mechanism when the door opened. This issue was resolved by installing a clear plastic cover to go over the mechanism and prevent the door being opened during Mx when the cover is not in place. Mx injuries can be prevented by placing the appropriate safety procedures in place and ensuring those procedures are followed......injuries and death caused by inefficeint egress unfortunately cannot be prevented without improving the egress. I'd hate to be the one who had to give this bad news:-

"I'm sorry your son (daughter, mother, father, brother sister, wife, husband etc,) died because they couldn't get out of the burning wreck fast enough. We did come up with a better exit which may have saved their lives, but too many mechanics were hurting themselves for not following procedures designed to prevent such injuries, so we decided against it."

(Before I get reamed) I know it's harsh, but it's the brutal truth in the airline industry and a lawyers paradise.

DD

 
Chiuaua
Posts: 102
Joined: Sun Apr 16, 2000 9:31 pm

RE: A320 And 737NG Emergency Exits!

Thu Oct 03, 2002 2:37 am

I wrote my message kind of stupid. Sorry for that. Just wanted to say that increased safety for a certain group of people might bring some hazards for another group. But ofcourse a mechanic should always remember to read safety instructions and be aware of what he or she is doing.

Greetz, Chiuaua

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