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Overwing Evacuation Question  
User currently offlineCubsrule From United States of America, joined May 2004, 23148 posts, RR: 20
Posted (6 years 5 months 2 weeks 12 hours ago) and read 6566 times:

On aircraft with overwing exits and no slides (e.g. CRJ, DC-9 variants, 737, etc.), if the flaps are not able to be lowered all the way, is it permissible to use the overwing exits anyway?


I can't decide whether I miss the tulip or the bowling shoe more
25 replies: All unread, showing first 25:
 
User currently offlineA10WARTHOG From United States of America, joined Jul 2004, 325 posts, RR: 0
Reply 1, posted (6 years 5 months 2 weeks 12 hours ago) and read 6565 times:

CRJ and ERJ wing roots set low enough it would not be a problem.

User currently offlineCubsrule From United States of America, joined May 2004, 23148 posts, RR: 20
Reply 2, posted (6 years 5 months 2 weeks 12 hours ago) and read 6565 times:



Quoting A10WARTHOG (Reply 1):
CRJ and ERJ wing roots set low enough it would not be a problem.

I figured that, and they might be on -9s (and progeny) too, but they certainly aren't on 737s.



I can't decide whether I miss the tulip or the bowling shoe more
User currently offlineEMBQA From United States of America, joined Oct 2003, 9364 posts, RR: 11
Reply 3, posted (6 years 5 months 2 weeks 6 hours ago) and read 6481 times:

Quoting Cubsrule (Thread starter):
if the flaps are not able to be lowered all the way, is it permissible to use the overwing exits anyway?

If you're given a reason to be going out the over wing exit.... trust me... you'll be motivated enough to do what ever it takes to get away from the plane

Quoting Cubsrule (Reply 2):
but they certainly aren't on 737s.

A 737 would be fine as well as the wing is really not that high off the ground. Looking at the drawings on the Boeing web site... and some pictures of people working around a 737 as scale.. I'd say its about 6ft at the trailing edge.

[Edited 2008-05-12 12:59:52]


"It's not the size of the dog in the fight, but the size of the fight in the dog"
User currently offlineCubsrule From United States of America, joined May 2004, 23148 posts, RR: 20
Reply 4, posted (6 years 5 months 2 weeks 4 hours ago) and read 6434 times:



Quoting EMBQA (Reply 3):

If you're given a reason to be going out the over wing exit.... trust me... you'll be motivated enough to do what ever it takes to get away from the plane

 checkmark But I know that evacuation checklists for pilots have flap extension on them... I'm curious what (if anything) the checklists say if the flaps cannot be extended.



I can't decide whether I miss the tulip or the bowling shoe more
User currently offlineMarkhkg From United States of America, joined Dec 2005, 960 posts, RR: 2
Reply 5, posted (6 years 5 months 1 week 5 days 20 hours ago) and read 6360 times:

Incidentally activation of the overwing slide on the B757/B767 automatically lowers the inboard spoilers if they are still deployed in the upright position.


Release your seat-belts and get out! Leave everything!
User currently offlineJetMech From Australia, joined Mar 2006, 2699 posts, RR: 53
Reply 6, posted (6 years 5 months 1 week 5 days 19 hours ago) and read 6358 times:



Quoting Markhkg (Reply 5):

Apparently on the 767, the spoiler lowering is accomplished using an explosive squib. I wonder if the 757 is similar?

Regards, JetMech



JetMech split the back of his pants. He can feel the wind in his hair.
User currently offlinePilotpip From United States of America, joined Sep 2003, 3150 posts, RR: 11
Reply 7, posted (6 years 5 months 1 week 5 days 7 hours ago) and read 6289 times:

The evacuation route on the ERJ is over the leading edge anyway.


DMI
User currently offlineCubsrule From United States of America, joined May 2004, 23148 posts, RR: 20
Reply 8, posted (6 years 5 months 1 week 5 days 6 hours ago) and read 6284 times:



Quoting Pilotpip (Reply 7):
The evacuation route on the ERJ is over the leading edge anyway.

The ERJ does have leading edge devices, though, right?



I can't decide whether I miss the tulip or the bowling shoe more
User currently offlinePilotpip From United States of America, joined Sep 2003, 3150 posts, RR: 11
Reply 9, posted (6 years 5 months 1 week 5 days 5 hours ago) and read 6262 times:

Nope.

It has VGs and vortillions but those are well outboard.



DMI
User currently offlineBellerophon From United Kingdom, joined May 2002, 584 posts, RR: 59
Reply 10, posted (6 years 5 months 1 week 5 days 5 hours ago) and read 6255 times:

Cubsrule

...I know that evacuation checklists for pilots have flap extension on them...

Some may, but none of the various passenger jet aircraft I've flown has had any mention of extending flaps on the evacuation checklist!

On most of them, the overwing door slides would have facilitated the egress of the passengers, and one type didn't have any flaps to lower anyway!  Wink

Evacuation checklists generally tend to focus on setting the park brake, shutting the engines down, ordering the evacuation and, should circumstances permit, telling ATC.

EMBQA has it spot on. If it is deemed necessary to evacuate an aircraft, use the nearest available exit, and if that happens to be an overwing exit, don't ignore it just because the flaps aren't fully out.

I can promise you I wouldn't!

Remember that the Captain is always the last flight crew member to leave the aircraft.
.
.
.
.
.
.
.
.
.
.
.
....as I hit the slide ahead of my F/O, he automatically becomes Captain! Big grin


Best regards

Bellerophon


User currently offlineEMBQA From United States of America, joined Oct 2003, 9364 posts, RR: 11
Reply 11, posted (6 years 5 months 1 week 5 days 3 hours ago) and read 6238 times:



Quoting Bellerophon (Reply 10):
I can promise you I wouldn't!

I was flying cockpit jumpseat once and told during the egress brief..."....if you're slow you'll be a foot stool...."



"It's not the size of the dog in the fight, but the size of the fight in the dog"
User currently onlineViscount724 From Switzerland, joined Oct 2006, 25638 posts, RR: 22
Reply 12, posted (6 years 5 months 1 week 5 days 2 hours ago) and read 6222 times:

Overwing exits are one thing you don't have to worry about on the BAe146/Avro RJ.  Smile


View Large View Medium
Click here for bigger photo!

Photo © Holger Frank



They have no window exits, just the forward and rear passenger and galley service doors.


User currently offlineHAWK21M From India, joined Jan 2001, 31684 posts, RR: 56
Reply 13, posted (6 years 5 months 1 week 4 days 19 hours ago) and read 6191 times:



Quoting JetMech (Reply 6):
Apparently on the 767, the spoiler lowering is accomplished using an explosive squib. I wonder if the 757 is similar?

No such Mechanism on the B752.
regds
MEL



Think of the brighter side!
User currently offlineLongHauler From Canada, joined Mar 2004, 5054 posts, RR: 43
Reply 14, posted (6 years 5 months 1 week 4 days 12 hours ago) and read 6168 times:



Quoting Bellerophon (Reply 10):
Some may, but none of the various passenger jet aircraft I've flown has had any mention of extending flaps on the evacuation checklist!

The B737 and the E190 series aircraft I have flown include it in the checklist, no others.

Not just the evacuation drill, but also the rejected takeoff drill.
In fact, in any occurrence where an evacuation is a possibility, the First Officer is expected to extend the flaps.



Never gonna grow up, never gonna slow down .... Barefoot Blue Jean Night
User currently offlineRoseFlyer From United States of America, joined Feb 2004, 9666 posts, RR: 52
Reply 15, posted (6 years 5 months 1 week 4 days 11 hours ago) and read 6164 times:



Quoting EMBQA (Reply 3):
A 737 would be fine as well as the wing is really not that high off the ground. Looking at the drawings on the Boeing web site... and some pictures of people working around a 737 as scale.. I'd say its about 6ft at the trailing edge.

The drop from a 737 is the maximum distance permissable by the FAA and various regulatory agencies. The 737 engines cowling does not have a circular outer diameter because the engine is so low to the ground. It needed the extra clearance by not being circular. Boeing has looked at going to a taller gear, but that would require evacuation sildes from the overwing exit, which would definitely add weight and that's not something that Boeing wants to do at all since all that equipment would be hundreds of pounds. A taller gear would also require a lot of modifications expecially in the forward wheel well since the pressure bulkhead would have to be moved. So the 737 is at the max allowed now.



If you have never designed an airplane part before, let the real designers do the work!
User currently offlineBAe146QT From United Kingdom, joined Sep 2006, 996 posts, RR: 0
Reply 16, posted (6 years 5 months 1 week 4 days 8 hours ago) and read 6149 times:



Quoting RoseFlyer (Reply 15):
The drop from a 737 is the maximum distance permissable by the FAA and various regulatory agencies.

I agree with EMBQA though. Imagine you're on a decapitated 747 slewed off the runway at Tenerife.

"But the FAA says we can't do this!"
"The who now? Oh. Um, yeah... you've got a point there. Guess we better burn then. Still at least it's warm."

To be fair, the OP asks whether it is permissable, not, "is it permissable as part of certification". And on a crashed aircraft, absent an instruction by the crew I'd be using that overwing exit as a last resort, not knowing the state of the engines or fuel tanks.



Todos mis dominós son totalmente pegajosos
User currently offlinePGNCS From United States of America, joined Apr 2007, 2833 posts, RR: 45
Reply 17, posted (6 years 5 months 1 week 4 days 7 hours ago) and read 6141 times:



Quoting Markhkg (Reply 5):
Incidentally activation of the overwing slide on the B757/B767 automatically lowers the inboard spoilers if they are still deployed in the upright position.

The 767 does have this feature; the 757 does not.


User currently offlineCubsrule From United States of America, joined May 2004, 23148 posts, RR: 20
Reply 18, posted (6 years 5 months 1 week 4 days 6 hours ago) and read 6131 times:



Quoting BAe146QT (Reply 16):
To be fair, the OP asks whether it is permissable, not, "is it permissable as part of certification".

Well, AFAIK, normal flap operation is assumed as part of the evacuation tests... all 'functional' exits are functioning normally. Whether or not that's a good test is a different question.



I can't decide whether I miss the tulip or the bowling shoe more
User currently offlineBAe146QT From United Kingdom, joined Sep 2006, 996 posts, RR: 0
Reply 19, posted (6 years 5 months 1 week 4 days 5 hours ago) and read 6124 times:



Quoting Cubsrule (Reply 18):
Well, AFAIK, normal flap operation is assumed as part of the evacuation tests... all 'functional' exits are functioning normally. Whether or not that's a good test is a different question.

Exactly, Cubs. I wasn't saying that Rose was wrong, just that the real world doesn't have the damned common courtesy to act like FAA tests expect. Manchester airport probably has a few ghosts who feel the same.

Isn't there someone here whose .sig block says something like, "regulations are made of paper and do a poor job of preventing flesh from meeting the earth"?



Todos mis dominós son totalmente pegajosos
User currently offlineKELPkid From United States of America, joined Nov 2005, 6407 posts, RR: 3
Reply 20, posted (6 years 5 months 1 week 4 days 5 hours ago) and read 6119 times:



Quoting BAe146QT (Reply 19):
Isn't there someone here whose .sig block says something like, "regulations are made of paper and do a poor job of preventing flesh from meeting the earth"?

Close  Wink



Celebrating the birth of KELPkidJR on August 5, 2009 :-)
User currently offlineKELPkid From United States of America, joined Nov 2005, 6407 posts, RR: 3
Reply 21, posted (6 years 5 months 1 week 4 days 5 hours ago) and read 6118 times:



Quoting Cubsrule (Reply 18):
Quoting BAe146QT (Reply 16):
To be fair, the OP asks whether it is permissable, not, "is it permissable as part of certification".

Well, AFAIK, normal flap operation is assumed as part of the evacuation tests... all 'functional' exits are functioning normally. Whether or not that's a good test is a different question.

I've heard, more than once, that in quite a few real-world evacuations, the overwing exits were never opened...it would be interesting if anyone has compiled statistics on that.

It makes sense to me, actually, since in 99% of all airliners, the wing is a huge fuel tank, and in probably 70-80% of those, underneath those fuel tanks is a really good source of heat, and in the case of an accident, probably open flame too  flamed  I could see where the cabin crew, at least, would be hesitant to open the overwing exits unless absolutely necessary.

You've got to love the exit row passenger safety cards, that say, in Ikeaspeak (you know, the iconographic language used on your new coffee table or bookshelf purhased at Ikea  Wink ), look for fire and wreckage outside the window before popping the emergency exit  Smile



Celebrating the birth of KELPkidJR on August 5, 2009 :-)
User currently offlineRoseFlyer From United States of America, joined Feb 2004, 9666 posts, RR: 52
Reply 22, posted (6 years 5 months 1 week 4 days 3 hours ago) and read 6091 times:



Quoting BAe146QT (Reply 19):

Isn't there someone here whose .sig block says something like, "regulations are made of paper and do a poor job of preventing flesh from meeting the earth"?

As someone who designs airplane parts and works around planes for a living, the regulations are what we build to. The certification requirements for an airplane don't just set guidelines, but are requirements. I acknowledge that if someone is able to jump 6ft and get away from the plane, then they probably won't break both legs and be paralyzed if they have to jump 6ft 1inch, but those are the regulations and we follow them. Without some overarching policy, then we would have nothing to design towards. I know that there's no super pilot out there who is going to stomp on the brakes with 150lbs of force, but they still have to be designed to take that load, but don't worry because no one will ever exert 151lbs of force on the rudder pedals.

Now parts are also designed for reality. We don't follow rules like the Titanic by not having enough equipment to save everyone, but things are designed with safety in mind. FMEA is done on most parts to evaluate the associated risks.



If you have never designed an airplane part before, let the real designers do the work!
User currently offlineKELPkid From United States of America, joined Nov 2005, 6407 posts, RR: 3
Reply 23, posted (6 years 5 months 1 week 4 days 2 hours ago) and read 6069 times:

Quoting RoseFlyer (Reply 22):
I know that there's no super pilot out there who is going to stomp on the brakes with 150lbs of force, but they still have to be designed to take that load, but don't worry because no one will ever exert 151lbs of force on the rudder pedals.

I could do it, but only on one pedal at a time   I'd have to stand up and put all my weight on the pedal...

I'd hate to see the results of a 302 lb. pilot standing up and putting his entire weight on both brakes  Wow!

Of course, I'm sure that RoseFlyer, being a good engineer, probably erred on the side of caution and designed the parts to 110% of the specified force... 

EDIT: along these lines, I've heard from a former US customs pilot that in the Convair 580, holding rudder against a dead engine in an engine-out requires every single once of strength from both the captain and the first officer.

[Edited 2008-05-15 16:36:33]


Celebrating the birth of KELPkidJR on August 5, 2009 :-)
User currently offlineRoseFlyer From United States of America, joined Feb 2004, 9666 posts, RR: 52
Reply 24, posted (6 years 5 months 1 week 4 days 1 hour ago) and read 6059 times:



Quoting KELPkid (Reply 23):
Of course, I'm sure that RoseFlyer, being a good engineer, probably erred on the side of caution and designed the parts to 110% of the specified force...

Nope, we don't design parts for 110% of specified force. We design them for the requirements. There isn't a cushion built in. If there was a 10% cushion on all the parts, think of how much extra weight you'd be flying around. Airplanes don't have tolerances like that. If the part is supposed to have an ultimate tensile strength of 150lbs, then we'll get as darn close to 150lbs as possible while making sure that 95%, 98.7%, 99.8% (or whatever spec you are using) of the parts will meet the requirement.

Now, for wing loading for example needs to be 150% of maximum load. Theh 777 wing made it to 154% of maximum load before it failed. Extra tolerance is not done. If we did, you wouldn't get off the ground.



If you have never designed an airplane part before, let the real designers do the work!
User currently offlineBAe146QT From United Kingdom, joined Sep 2006, 996 posts, RR: 0
Reply 25, posted (6 years 5 months 1 week 3 days 8 hours ago) and read 6013 times:



Quoting KELPkid (Reply 20):
Close Wink

Ahh, thank you.  Smile

Quoting RoseFlyer (Reply 22):
As someone who designs airplane parts and works around planes for a living, the regulations are what we build to.

I absolutely understand - really I do, because yours is not the only industry to do so. And as you point out, the reasons are obvious - you build to be safe and legally compliant, yet efficient. Those rules will be determined partly by operating costs, partly by material tolerances, partly by political lobbying and partly by averaging out what people can take, I should think. As I said in Post 19, you can make a regulation, and you can build to it, but people have a fascinating habit of defying regulations when they have to.

One last note: Hopefully the Pinto is something that can't happen again.

Quoting RoseFlyer (Reply 24):
If the part is supposed to have an ultimate tensile strength of 150lbs, then we'll get as darn close to 150lbs as possible

Did you know that the US DOH&HS has guidelines for exactly how much cattle faeces and insect remains are allowed to be present in ground beef? There used to be a rumour that the chop-shops employed QA inspectors to ensure that exactly that amount of crap and bugs were present. Obviously I don't believe that.



Todos mis dominós son totalmente pegajosos
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