I flew with guy yesterday who was thinking about buying a DA-20 or similer comosite constructed aircraft. As we were talking about adavantages and disadvantages of buying a newer composite vs. an older single (Archer, 172 etc.) he asked me about airframe life of a composite aircaraft. I am unsure about specifics in this area, if there is a max life for a composite aircraft or what long term tests have shown. Does a composite airframe have a limited life, or have substantial differences in durablity than a aluminum aircraft? Thanks for your respones.
Composite Airframe Lifespan
- Thread starter JK7177
- Start date
jynxyjoe
Queso King
Typically on Composite frames you will have some interval when the Feds will want to see a report about how the structures apoxy... I mean bonding... is holding up. In the case of the Starship, the structural bonding was (as predicted) greater than off the assembly line. At that time they set some future period to look at it or else finally gave it some longer life.
I've been out of it for a bit, but every airframe, composite or metal, is going to have some set lifetime which, at the end of the term, it will be reassessed and extended.
I've been out of it for a bit, but every airframe, composite or metal, is going to have some set lifetime which, at the end of the term, it will be reassessed and extended.
TUCKnTRUCK
That guy
One of the guys that I race with put some carbon bat wheels on his bike. He exceeded their design life, and all was fine... Untill they failed. Composites do not fail nice. By all looks on it, the rear literaly exploded under heavy acceleration. Metal will loose a bead, or get banged out of true, but you usually get warning.
I prob wouldn't want to test it in an airplane. Another issue being the UV exposure. A glass plane sitting on a ramp forever will age much worse than a metal one
I prob wouldn't want to test it in an airplane. Another issue being the UV exposure. A glass plane sitting on a ramp forever will age much worse than a metal one
jynxyjoe
Queso King
Hehe. No composites don't fail nice.
I doubt the composite on the bike went through the engineering or testing (validation) that the Starship went through though.
ILSstud
Well-Known Member
Back in one of my materials lab we put composite elements under tensile loading and compared it to the behavior of typical air frame aluminum and titanium. Watching the carbon fiber just "pop" and fail made me leery of composites. I suppose with proper inspections it is ok, but they didn't seem to have much give when compared to their metal counterparts. Also if I remember correctly, while composites might be stronger they don't withstand fatigue oscillations as well as metals do. The normal stress-strain curve of metal has the plastic region, whereas most composites (like carbon fiber) do not exhibit that behavior. I didn't realize the Diamond had an unlimited life, that's nice.
KSCessnaDriver
Well-Known Member
Yeah, the Diamond (DA-40) has unlimited life, if your wing doesn't fall apart, which has been the subject of an AD. Apparently, they had some issues with the spar de-laminating from the skin. To test it, the A&P's needed this hammer, that they got the pleasure of tapping the length of the spar on each wing, to listen for a difference in noise. Did I mention there are 2 spars? Anyway, if it was bad enough, you had to pull the wing, and put a new one on.
bdhill1979
Gone West
Maybe, I got to witness the first katanas come up on the 6000 hour limit and Diamond took almost a year to figure out if they could continue flying. Unlimited life with a heavy amound of Mx would be more appropriate.
Seen that twice, plus about a dozen other delamination issues, including the delamination of the landing gear actuator plate on a DA42.
KSCessnaDriver
Well-Known Member
Yup, lots of the Diamond's will be nothing more than shredded glass, recycled back into some composite material, long before Northwest's (er, I mean Delta's) DC-9's are recycled into your Pepsi can.
bdhill1979
Gone West
ewww Pepsi??????
Yeah, I will take my 42 year old Cessna over a flying sperm any day of the week.
Douglas
Old School KSUX
yes sir!
KSCessnaDriver
Well-Known Member
I don't mind either (Spam can vs composite). They each have their respective pro's/con's. Its just what you need for the mission of the day.
bdhill1979
Gone West
Every day the mission is:
Speed
useful load
seats that are not changing the shape of my spine
not having to do a pre-takeoff knees and nuts check
Shade in the Cockpit
KSCessnaDriver
Well-Known Member
Every day the mission is:
Speed
useful load
seats that are not changing the shape of my spine
not having to do a pre-takeoff knees and nuts check
Shade in the Cockpit
That is defiantly not a Diamond. Nor is it really a 172 or something like that, either.
TUCKnTRUCK
That guy
sorry, was BST wheel, the iphone changed it. BST had to meet a lot of inspections to get their wheels DOT and ama certified. That is why they are limited to a service life of a certain number of tire changes.
jwp_145
GhostRider in the Sky
What kind of racing your buddy doing? I motocrossed all my life up until I destroyed a leg... Spynnergy has some new wheels for the motocross market... total wheel kit is 2 GRAND!!!!!
TUCKnTRUCK
That guy
Used to ride in Super twins at what is now NHIS louden nh) I ride an Aprilia, I stick with the forged Oz's that came on the bike though... The weight savings of carbon isn't worth it..
