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FAA Issues Proposed Special Condition Re 787  
User currently offlineAmicus From United States of America, joined Mar 2007, 43 posts, RR: 0
Posted (7 years 5 months 3 weeks 5 days 18 hours ago) and read 12361 times:

On March 30th, the FAA issued "proposed special condition" re "Composite Wing and Fuel Tank Structure- Fire Protection Requirements" (Docket Number NM366, Notice No. 25-07-03-SC). Proposed condition requires: "Boeing to demonstrate acceptable post-crash survivability in event wings are exposed to large fuel-fed ground fire. Boeing must demonstrate that the wing and fuel tank design can endure an external fuel-fed pool fire for at least 5 minutes. Considerations shall include fuel tank flammability, burn through resistance, wing structural strength retention properties and auto-ignition threats during a ground fire event for the required time duration."

Comments and observations, please.

48 replies: All unread, showing first 25:
 
User currently offlineFriendlySkies From United States of America, joined Aug 2004, 4107 posts, RR: 5
Reply 1, posted (7 years 5 months 3 weeks 5 days 17 hours ago) and read 12293 times:

Sounds fair...

And from testing of the CFRP material, the burn-through time is actually greater than that of aluminum. I'm sure Boeing isn't sweating over this.


User currently offlineFerret From United States of America, joined Jun 2000, 123 posts, RR: 0
Reply 2, posted (7 years 5 months 3 weeks 5 days 17 hours ago) and read 12111 times:

How do these requirements differ, if at all, from a conventional wing and tank requirement?


Murphy lives here.
User currently offlineCurmudgeon From Australia, joined Oct 2006, 695 posts, RR: 22
Reply 3, posted (7 years 5 months 3 weeks 5 days 17 hours ago) and read 12108 times:

That's interesting. I wonder if the test conditions call for full or nearly empty tanks? Does someone have the aluminum wing requirements (if any) handy? (Fuselage skins have burned through in 12 seconds, as I recall from one accident report).

A friend was in a 737 fuel truck fire incident like this...a burning pool of fuel under the aircraft. It occurred before passenger boarding, and he reports that the entire aircraft was ablaze within 3 minutes-a total loss even with a quickish response from the airport fire service.



Jets are for kids
User currently offlineSphealey From United States of America, joined May 2005, 377 posts, RR: 0
Reply 4, posted (7 years 5 months 3 weeks 5 days 17 hours ago) and read 12069 times:

> Comments and observations, please.

I guess the proof test article won't be going to a museum  Wink

sPh


User currently offlineCygnusChicago From United States of America, joined Mar 2007, 758 posts, RR: 1
Reply 5, posted (7 years 5 months 3 weeks 5 days 17 hours ago) and read 12069 times:

That's interesting - won't these same conditions already be in place for Airbus aircraft with composites in the wing, especially the A400M, or is it exempt as it is a military plane?

Quoting Amicus (Thread starter):
Comments and observations, please.

You sound like a schoolteacher



If you cannot do the math, your opinion means squat!
User currently offline777236ER From , joined Dec 1969, posts, RR:
Reply 6, posted (7 years 5 months 3 weeks 5 days 17 hours ago) and read 12047 times:

A good thing from the point of view of passenger safety. Legislation is surprisingly lax regarding pooled-fuel fires - see the Manchester airport fire to see just how rapidly devastating they can be.

User currently offlineKELPkid From United States of America, joined Nov 2005, 6398 posts, RR: 3
Reply 7, posted (7 years 5 months 3 weeks 5 days 16 hours ago) and read 11987 times:

Quoting FriendlySkies (Reply 1):
And from testing of the CFRP material, the burn-through time is actually greater than that of aluminum. I'm sure Boeing isn't sweating over this.

Wonder if ARFF services around the world will have to update the firefighting foam that they use? Isn't it designed mostly to keep metal from burning, and not primary carbon structure?



Celebrating the birth of KELPkidJR on August 5, 2009 :-)
User currently offlineLMP737 From , joined Dec 1969, posts, RR:
Reply 8, posted (7 years 5 months 3 weeks 5 days 16 hours ago) and read 11980 times:

Quoting CygnusChicago (Reply 5):
That's interesting - won't these same conditions already be in place for Airbus aircraft with composites in the wing, especially the A400M, or is it exempt as it is a military plane?

I don't what the laws are in Europe regarding military aircrat but in the US any aircraft that's to fly for the US military has to show a certain level of survivablity.


User currently offlineMCIGuy From United States of America, joined Mar 2006, 1936 posts, RR: 0
Reply 9, posted (7 years 5 months 3 weeks 5 days 16 hours ago) and read 11910 times:

This is kind of old news. Of course there will be new hoops for the first plastic airliner to jump through, there should be given the radical departure from traditional design. Last I heard, Boeing is helping the FAA "write the book" on the 787 and future composite planes.


Airliners.net Moderator Team
User currently offlineAmicus From United States of America, joined Mar 2007, 43 posts, RR: 0
Reply 10, posted (7 years 5 months 3 weeks 5 days 16 hours ago) and read 11814 times:

Under "novel and unusual design features proposed SC states:
" Conventional aircraft with aluminum skin and structure provide a well understood level of safety during post-crash scenarios with respect to fuel tanks.......Composites may or may not have capabilities equivalent to aluminum and current regulations do not provide objective performance requirements for wing and fuel tank structure with respect to post-crash safety."
Also per SC:
" The extensive use of composite materials in the design of the 787 wing and fuel tank structure is considered a major change from conventional and traditional methods of construction This is the first large transport category aircraft to be certificated with this level of composite material for these purposes. The applicable airworthiness regulations to not contain specific standards for post -crash fire safety performance of wing and fuel tank skin or structure. "

Re earlier fuel load question:
SC states:
"This shall be demonstrated for minimum fuel loads (not less than reserve fuel levels) and
maximum fuel loads (maximum range fuel quantities) and other identified critical fuel loads".

Quoting CygnusChicago (Reply 5):
That's interesting - won't these same conditions already be in place for Airbus aircraft with composites in the wing, especially the A400M, or is it exempt as it is a military plane?

Quoting Amicus (Thread starter):
Comments and observations, please.

You sound like a schoolteacher

No, just a aerospace composites structural engineer with over 40 years of composites experience.

Quoting FriendlySkies (Reply 1):
Sounds fair...

And from testing of the CFRP material, the burn-through time is actually greater than that of aluminum. I'm sure Boeing isn't sweating over this.

Sensible engineers sweat everything until proven by test and Boeing has lots of sensible and superb engineers and I am sure will be sweating it until all results of test are in.


User currently offlineAmicus From United States of America, joined Mar 2007, 43 posts, RR: 0
Reply 11, posted (7 years 5 months 3 weeks 5 days 16 hours ago) and read 11778 times:

Quoting MCIGuy (Reply 9):
This is kind of old news. Of course there will be new hoops for the first plastic airliner to jump through, there should be given the radical departure from traditional design. Last I heard, Boeing is helping the FAA "write the book" on the 787 and future composite planes.

I fail to see as old news if FAA just published proposed SC on March 30th 2007


User currently offlineEI321 From Iraq, joined Jul 2009, 0 posts, RR: 0
Reply 12, posted (7 years 5 months 3 weeks 5 days 15 hours ago) and read 11716 times:

Quoting Amicus (Thread starter):
Comments and observations, please.

Interestesting. Was Boeing expecting this?


User currently offlineMCIGuy From United States of America, joined Mar 2006, 1936 posts, RR: 0
Reply 13, posted (7 years 5 months 3 weeks 5 days 15 hours ago) and read 11626 times:

Quoting Amicus (Reply 11):
I fail to see as old news if FAA just published proposed SC on March 30th 2007

I was just saying that there was a recent thread about this already. Nothing personal man, no insult intended. Smile



Airliners.net Moderator Team
User currently offlineCurmudgeon From Australia, joined Oct 2006, 695 posts, RR: 22
Reply 14, posted (7 years 5 months 3 weeks 5 days 15 hours ago) and read 11594 times:

The more that I reflect on this SC, as noted in Amicus's brief, the more I wonder if this isn't shooting from the hip on the part of the FAA.

1. Their stated aim is to ensure an equivalent level of safety to aluminum wings.
2. They are releasing this now, on the eve of the test program? Are they just getting around to thinking about the ramifications of composites?
3. Have they tested a representative sample of conventional wing structures? If not, why not? How have they
determined that five minutes fire resistance is equivalent to a metal wing? What if someone showed a metal wing burning through in less than five minutes? Does the test requirement call out temperatures, or elevation of the structure above the fuel pool?
4. On the face of it, an aerated fuel pool fire below the wing structure would be pretty hard to resist, I'd think. The temperatures reached could be ferocious, and 300 seconds is a long time.



Jets are for kids
User currently onlineStitch From United States of America, joined Jul 2005, 31062 posts, RR: 87
Reply 15, posted (7 years 5 months 3 weeks 5 days 15 hours ago) and read 11513 times:
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Well some folks were recently of the opinion that the FAA was going to "cook the books" to give the 787 a cleaner (and, allegedly, riskier to passengers) path to certification. So if the FAA is indeed requiring Boeing to at least meet current standards on Al aircraft then that will hopefully allay some of the possible fears the traveling public may have.

[Edited 2007-04-10 00:50:15]

User currently offlinePygmalion From United States of America, joined Jun 2006, 966 posts, RR: 38
Reply 16, posted (7 years 5 months 3 weeks 5 days 15 hours ago) and read 11501 times:

Boeing has been working special condition definitions with the FAA since the start of the program. It's all about defining the cert basis for the aircraft. Since no regulations exist for this... Boeing, the FAA and EASA work together to define new ones. Special conditions are how new, novel parts/constructions are handled.

When the regulations don't define how to certify a new design, the manufacturer and the regulatory agency work together to define how they will certify the aircraft is airworthy. This should be no surprise to anyone and is not a surprise to the FAA and Boeing.


User currently onlineRuscoe From Australia, joined Aug 1999, 1567 posts, RR: 2
Reply 17, posted (7 years 5 months 3 weeks 5 days 14 hours ago) and read 11385 times:

Quoting Amicus (Reply 10):
No, just a aerospace composites structural engineer with over 40 years of composites experience

Would you mind giving us your thoughts on how Composites might behave in this situation?

Thanks
Ruscoe


User currently offlineIkramerica From United States of America, joined May 2005, 21534 posts, RR: 59
Reply 18, posted (7 years 5 months 3 weeks 5 days 14 hours ago) and read 11342 times:

I guess 5 minutes is the time they've decided that survivors would need to assess the situation, open the doors, evacuate and get far enough away from the plane so they wouldn't be killed from the explosion.

One assumes there can only be a "pooling" fuel fire if the plane has come to rest, right?



Of all the things to worry about... the Wookie has no pants.
User currently offlineEI321 From Iraq, joined Jul 2009, 0 posts, RR: 0
Reply 19, posted (7 years 5 months 3 weeks 5 days 14 hours ago) and read 11250 times:

Quoting Stitch (Reply 15):
Well some folks were recently of the opinion that the FAA was going to "cook the books" to give the 787 a cleaner (and, allegedly, riskier to passengers) path to certification.

I think that assertion (by some) is BS. Neither Boeing nor the FAA can afford to play that kind of game. Theres just too much riding on the 787 to risk cutting corners like that.


User currently offlineChiGB1973 From United States of America, joined Mar 2004, 1616 posts, RR: 1
Reply 20, posted (7 years 5 months 3 weeks 5 days 14 hours ago) and read 11242 times:

If you can't get out, a 5 minute window might mean the difference between fire/rescue arriving on scene in time to keep you from essentially baking in an oven. I am just assuming that the aircraft isn't escapable, fire/rescue could arrive within 5 minutes and there is a pool of fuel burning. Many assumptions; the LEX accident might have added some concern, if, in fact, this was a factor.

M


User currently offlineIkramerica From United States of America, joined May 2005, 21534 posts, RR: 59
Reply 21, posted (7 years 5 months 3 weeks 5 days 13 hours ago) and read 11193 times:

Quoting ChiGB1973 (Reply 20):
I am just assuming that the aircraft isn't escapable, fire/rescue could arrive within 5 minutes and there is a pool of fuel burning.

That's a good point. On a runway overrun, 5 minutes should be enough time for crews to arrive and start putting it out, but I can't see them getting it completely under control in that time.

Then again, I'm not a fireman, so maybe they can?!



Of all the things to worry about... the Wookie has no pants.
User currently offlineDomokun From United States of America, joined Sep 2006, 202 posts, RR: 0
Reply 22, posted (7 years 5 months 3 weeks 5 days 13 hours ago) and read 11009 times:

Quoting ChiGB1973 (Reply 20):
If you can't get out, a 5 minute window might mean the difference between fire/rescue arriving on scene in time to keep you from essentially baking in an oven. I am just assuming that the aircraft isn't escapable, fire/rescue could arrive within 5 minutes and there is a pool of fuel burning.

If you can't get out, you have a separate major problem. What if nobody could have gotten of the AF A340 which overran? Fire survivability is one thing, getting out is another  Smile


User currently offlineChiGB1973 From United States of America, joined Mar 2004, 1616 posts, RR: 1
Reply 23, posted (7 years 5 months 3 weeks 5 days 13 hours ago) and read 10907 times:

Quoting Domokun (Reply 22):
If you can't get out, you have a separate major problem.

I don't know that I would say separate, just additional.

M


User currently offlineHughesAirwest From United States of America, joined Dec 2006, 51 posts, RR: 0
Reply 24, posted (7 years 5 months 3 weeks 5 days 11 hours ago) and read 9973 times:

I remember back in August of 06 that either NGC or Discovery channel had a special on the A380 and the cameras had to be turned off due to the "special" bonding process of there wings. Aren't the A380's wings made up of composites? If so the why did Airbus not have to demonstrate this.


"One man practicing Teamwork is far better than fifty preaching it."
25 Amicus : Seems time to surface again to answer some of the excellent points raised in this thread. No offence here, but if you check earlier thread, I was offe
26 Amicus : Certainly, and there was a recent clue in the 787 quarterly web-cast where it was mentioned that: "There is a lot of debate going on internally wheth
27 Ruscoe : Thankyou for that. So if it fails to meet the 5 minute rule, is there a fix which could be incorporated within the certification testing time frame,
28 Post contains images Curmudgeon : This goes to my sarcastic comment about only just realising this now. They knew that composites were coming for quite some time now, and they missed
29 Ruscoe : To answer my own question,I have asked a non aerospace engineer who has general knowledge, and he said that heat damage to CFRP laminates, spreads rap
30 Mustang304 : The military transport plans are sometimes equipped with a system called OBIGGS (On Board Inert Gas Generating System), a system that produces Nitrog
31 NYC777 : From what I understand Boeing IS going to be using a nitrogen generator (similar to OBIGGS) for the fuel tanks on the 787 to fill up the empty space.
32 USAF336TFS : I'll go out on a limb here and say that there are those that are praying for anything would provide a pretext for a program delay. The bad news for t
33 Stitch : Does not the fuel tank inerting standard apply only to the center fuel tank, which the A388 does not have? I am pretty sure that Airbus has said it wi
34 Rheinbote : A few things to consider: - the A380's CFRP center wing box is almost completely buried within the fuselage, the wing boxes sticking out left and righ
35 Amicus : Regarding your responses and thoughts, I could answer point by point, but think more useful, first, to discuss background and known issues. First, ob
36 Curmudgeon : Speaking as the chief protester in this thread, thanks very much for your thoughtful and informative reply. Your background information is clear and h
37 Pygmalion : Another piece to this story is that putting out a "proposed special condition" for comments is where the non-boeing community gets to weigh in on the
38 Pygmalion : And to directly answer Curmudgeon's point... My best guess for the center wing tank on the A380 for fuel tank fire is that it is either shielded from
39 Post contains images Stitch : The A380-800 does not have a center wing tank, so it doesn't need anything special. The A380-800F does, but again, I believe Airbus has said they wil
40 Curmudgeon : Thanks, Pygmalion. I am even more bemused now, after reading your post that the A380 SC's were in place in 1998, before the program launch-compared to
41 Post contains links Pygmalion : Curmudgeon, Just to be sure I didn't mislead.... Airbus asked for type cert basis definition for the A380-800 in 1998. The negotiations start then. Mo
42 Pygmalion : also... engines hold the outer wing off the ground in most cases so the lower wing surface has more exposed burn area. Any part actually in the fuel w
43 Amicus : Cur, All thanks for yours and your comments and insights, they are appreciated, and on this specific issue there was a bunch of research done during
44 XT6Wagon : Aluminum makes a great fuel. You at least used to be able to see when someone was about to lose their motor in NASCAR as it would suddenly be making
45 Post contains images WingedMigrator : Only as an option. I don't think that any of the former customers selected this.
46 Flyabunch : Thanks for a great thread. I am not qualified to contribute to the substance of the discussion but that does not mean that I do not appreciate the top
47 Post contains images Curmudgeon : This happened to me one night when the air cooling passage blocked on a cylinder in my 356. That was one comprehensively messed up motor afterward. T
48 Post contains images MCIGuy : Aluminum accounts for much of the product that's inside firecrackers.
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