Sponsor Message:
Aviation Technical / Operations Forum
My Starred Topics | Profile | New Topic | Forum Index | Help | Search 
Cfrp Airliners: How Long A Useful Life?  
User currently offlinefaro From Egypt, joined Aug 2007, 1556 posts, RR: 0
Posted (3 years 1 month 3 weeks 1 day 9 hours ago) and read 3803 times:

Given that CFRP presents much less fatigue issues, how much longer useful life will the likes of the 787 and A350 have in terms of hours and flight cycles? Will this increased life actually be used by airlines or will it translate into a glut of freighters on the market in 20 years' time from now?

Faro


The chalice not my son
8 replies: All unread, jump to last
 
User currently offlinetdscanuck From Canada, joined Jan 2006, 12709 posts, RR: 80
Reply 1, posted (3 years 1 month 3 weeks 1 day 6 hours ago) and read 3776 times:

Quoting faro (Thread starter):

Given that CFRP presents much less fatigue issues, how much longer useful life will the likes of the 787 and A350 have in terms of hours and flight cycles?

Tough to tell. However, if other examples of very long-life airliners are any guide, we're probably talking 30-40 years (+50-100% hours/cycles). They will likely become economically obsolete before their structure gives out.

Keep in mind that there is still metal in there in crucial places and it's all got a finite fatigue life. It might not pay to replace, say, a fuselage splice plate 30 years from now.

Quoting faro (Thread starter):
Will this increased life actually be used by airlines or will it translate into a glut of freighters on the market in 20 years' time from now?

Some of both, I expect. 20 years from now we'll have to have made more progress in efficiency, so only some airlines will have route and business models where a then "antiquated" 787/A350 can make money.

Tom.


User currently offlinefaro From Egypt, joined Aug 2007, 1556 posts, RR: 0
Reply 2, posted (3 years 1 month 2 weeks 1 day 5 hours ago) and read 3412 times:

Quoting tdscanuck (Reply 1):
Quoting faro (Thread starter):

Given that CFRP presents much less fatigue issues, how much longer useful life will the likes of the 787 and A350 have in terms of hours and flight cycles?

Tough to tell. However, if other examples of very long-life airliners are any guide, we're probably talking 30-40 years (+50-100% hours/cycles). They will likely become economically obsolete before their structure gives out

I wonder then if the airframes can last such a long time whether re-engining will become the trend of the future. Barring the development of practical BWB aircraft (commercial obstacles, costly) or some spectacular breakthrough in wing aerodynamics (unlikely), engines are where the majority of future efficiency gains are likely to come from. Don't be surprised if a significant proportion of 787/A350 frames are still plying the skies +40 years from production date...

Faro



The chalice not my son
User currently onlineStitch From United States of America, joined Jul 2005, 31117 posts, RR: 85
Reply 3, posted (3 years 1 month 2 weeks 1 day 3 hours ago) and read 3366 times:
Support Airliners.net - become a First Class Member!

Quoting faro (Thread starter):
Given that CFRP presents much less fatigue issues, how much longer useful life will the likes of the 787 and A350 have in terms of hours and flight cycles?

A CFRP structure eventually reaches a "fatigue floor" at which point no further degradation occurs regardless of how many cycles / hours of wear are generated. So in theory, the fuselage and wings of a 787 or A350 have no limits. I say in theory because the fasteners and such do have a maximum-rated life along with the other systems.

However, we have DC-9s today that are approaching the half-century mark so I fully expect that we will see 787s and A350s in passenger revenue service a half-decade after delivery. And if the passenger airframes are suitable for conversion to freighters and the systems can be kept up to date for a reasonable cost, it just may not be outside of the realm of possibility to see a 787BCF or A350P2F crossing the 75 year mark or even the century mark.   


User currently offlinefaro From Egypt, joined Aug 2007, 1556 posts, RR: 0
Reply 4, posted (3 years 1 month 2 weeks 1 day 3 hours ago) and read 3364 times:

Quoting Stitch (Reply 3):
it just may not be outside of the realm of possibility to see a 787BCF or A350P2F crossing the 75 year mark or even the century mark.

Or even doing the pax charter circuits with refitted open-rotors or 70,000 lb GTF's...

Faro



The chalice not my son
User currently offline474218 From United States of America, joined Oct 2005, 6340 posts, RR: 9
Reply 5, posted (3 years 1 month 2 weeks 1 day 1 hour ago) and read 3326 times:

Does any you know how many cycles the the 787 fatigue test airframe was subject too. Common practice is to divide the number of test cycles achieved and then divide that number in half for the designed service fife.

User currently offlinetdscanuck From Canada, joined Jan 2006, 12709 posts, RR: 80
Reply 6, posted (3 years 1 month 2 weeks 18 hours ago) and read 3267 times:

Quoting Stitch (Reply 3):
A CFRP structure eventually reaches a "fatigue floor" at which point no further degradation occurs regardless of how many cycles / hours of wear are generated. So in theory, the fuselage and wings of a 787 or A350 have no limits.

That's only true if the fatigue floor is high enough that it's still good for limit load...that's unlikely to be the case (too heavy).

Quoting 474218 (Reply 5):
Does any you know how many cycles the the 787 fatigue test airframe was subject too.

They passed 10,000 back in May:
http://www.flightglobal.com/blogs/fl...boeing-passes-10000-cycles-on.html

Quoting 474218 (Reply 5):
Common practice is to divide the number of test cycles achieved and then divide that number in half for the designed service fife.

That doesn't determine design service life...design life is a target established at the beginning. The requirement is that the fatigue test article has to go (at least) to double the design life but it doesn't have to do that before certification. According to the flight global article, they just need to stay 10,000 cycles ahead of the fleet leader.

Tom.


User currently offline474218 From United States of America, joined Oct 2005, 6340 posts, RR: 9
Reply 7, posted (3 years 1 month 2 weeks 6 hours ago) and read 3195 times:

Quoting tdscanuck (Reply 6):
That doesn't determine design service life...design life is a target established at the beginning. The requirement is that the fatigue test article has to go (at least) to double the design life but it doesn't have to do that before certification. According to the flight global article, they just need to stay 10,000 cycles ahead of the fleet leader.

That may be way Boeing is doing it now but, when the Aging Aircraft Task Force was established, and all commercial aircraft with a MGTO weight of over 75,000 lbs had to provide a Design Life Goal what I stated was the criteria used. Additionally if the OEM did not provide a DLG the FAA would establish one for them using that basic criteria.

I must use my experience on the L-1011. If you have seen pictures of the L-1011 fatigue test airframe it did not have a flight station. Instead it had had a metal fitting that was used to pressurize the fuselage, which meant the flight station had to be tested separately. So while the entire airframe, less the flight station, was tested to 84,000 flight cycles. The separate flight station test stopped at 72,000 flights. One half of 72,000 is 36,000 the design life goal of the L-1011.


User currently offlinecmf From , joined Dec 1969, posts, RR:
Reply 8, posted (3 years 1 month 1 week 5 days 17 hours ago) and read 3070 times:

Quoting tdscanuck (Reply 6):
they just need to stay 10,000 cycles ahead of the fleet leader.

A bit picky but IIRC it is minimum twice the number of cycles and not less than 10,000 above the fleet leader.


Top Of Page
Forum Index

Reply To This Topic Cfrp Airliners: How Long A Useful Life?
Username:
No username? Sign up now!
Password: 


Forgot Password? Be reminded.
Remember me on this computer (uses cookies)
  • Tech/Ops related posts only!
  • Not Tech/Ops related? Use the other forums
  • No adverts of any kind. This includes web pages.
  • No hostile language or criticizing of others.
  • Do not post copyright protected material.
  • Use relevant and describing topics.
  • Check if your post already been discussed.
  • Check your spelling!
  • DETAILED RULES
Add Images Add SmiliesPosting Help

Please check your spelling (press "Check Spelling" above)


Similar topics:More similar topics...
How Long Do You Think A 737 Can Be Streched? posted Mon Jan 3 2011 15:47:00 by 747400sp
How Long Is Your Flight? posted Sun Jul 25 2010 08:32:11 by AncientPelican
How Long Do It Take To Fuel An A380? posted Tue Feb 2 2010 17:00:50 by 747400sp
How Long To Put Together A B773ER? posted Mon Jul 27 2009 18:30:44 by PRFlyer
How Long Are Aircraft Stored In The Desert? posted Wed Nov 19 2008 18:13:38 by Sovietjet
How Long Do Airlines Keep Maintenance Records? posted Fri Nov 14 2008 09:42:06 by Deaphen
How Long Does It Take To Fuel An A380? posted Thu Nov 6 2008 10:37:19 by Soxfan
How Long Does It Take To Assemble An Aircraft posted Mon Nov 3 2008 22:44:18 by Anthsaun
How Long It Takes To Fully Power 747 Classic? posted Tue Oct 28 2008 19:20:42 by 747400sp
About How Long Do You Think The A389 Will Be? posted Thu Oct 23 2008 20:09:44 by 747400sp

Sponsor Message:
Printer friendly format