Composite Aircraft in the long term...

(Rick Durden) wrote:

The UV issue was dealt with 20 years ago as well.

That's debatable. Improvements have been made, but toxicity
concerns have caused some formula changes. I think the jury
is still out.

Todd Pattist
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Rick Durden wrote:

snip

Because of the FAA's extremely conservative certification procedures
for composites, the structures are far, far stronger than metal
airplanes, which is why they also weigh as much. The FAA
certification procedures took away the weight advantage of composites,
but what it did was give us airplanes that are evern more overbuilt
than the Grumman Ironworks figthers of WWII.

Generalising quite a bit there a few other issues apart from the
conservative safety factor in strength requirements which tend to increase
weight in composites.

The stiffness issue which often requires extra material (most composites
have 1% strain at yield)

Low work of fracture compared to metals.

Difficulty in inspection for defects especially after minor impact damage
considering that damage can be at some distance from the impact point.


regards

jc

Jay Honeck wrote:
Okay, so Cirrus is cooking along at 60 aircraft per month. They're selling
everything they can build, and people who have bought them are ecstatic.

Fast forward to the year 2018. What's going to be happening to these
composite beauties?

A recent Hot Topic in the local aerobatic community as the recent
economic situation has driven several 12-14 year old Extra 300 aircraft
onto the market. These birds have 2000 to 2500 hours on them, with a
factory limit life of 5000 hrs. These aircraft have been rode hard as
flight demonstration team aircraft and appear fine. But, until someone
puts the requisite 5000 hrs on one and sends it back to be cut up by the
factory for examination it's anybodys guess what the insides look like.

Lots of anguish over a recent article in Sport Aerobatics when Bud
Davisson had his 30 year old S2A recovered and found lots of
weakened/broken glue joints in his wings. Everything was repairable
using well established procedures. Nothing like being able to tear off
the old cover and get in and have a look around! Try that with your 300k
dollar composite airplane!

Jerry

The TCDS shows the SR 22 has a 4350 hour airframe life.

http://www.airweb.faa.gov/Regulatory...E?OpenDocument

(Long site name - I don't know if copying and pasting will work)


... Extra 300 aircraft onto the market. These birds have 2000 to 2500 hours on them, with a factory limit life of 5000 hrs...

Jerry Guy wrote:

These birds have 2000 to 2500 hours on them, with a
factory limit life of 5000 hrs. These aircraft have been rode hard as
flight demonstration team aircraft and appear fine. But, until someone
puts the requisite 5000 hrs on one and sends it back to be cut up by the
factory for examination it's anybodys guess what the insides look like.

The early composite gliders had hour limits on the
structure. When they reached those limits, the aircraft
were inspected, without any cutting up, and the lifetimes
were all extended by the authorities. I'm not aware of any
composite structures with lifetime limits that had anything
more onerous than an inspection requirement before
extending.

Todd Pattist
(Remove DONTSPAMME from address to email reply.)
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Make a commitment to learn something from every flight.
Share what you learn.

here is an example of an 18 year old composite going strong.
http://www.geocities.com/CapeCanaver...l/1653/q1.html

think about helicopter rotor blades that last for many many years and flex
like crazy!

--
Have a good day and stay out of the trees!
See ya on Sport Aircraft group
http://groups.yahoo.com/group/Sport_Aircraft/

Flying Gators annual Fly-in
http://www.mitchellwing.com/flying_g...annual_fly.htm

Gilan, I went and looked at all the pages of your site. Very interesting to
see the amount of worked you put in to that construction project. You have a
plane to be proud of.

J.P.


"Gilan" a écrit dans le message news:
.net...
here is an example of an 18 year old composite going strong.
http://www.geocities.com/CapeCanaver...l/1653/q1.html

think about helicopter rotor blades that last for many many years and flex
like crazy!

--
Have a good day and stay out of the trees!
See ya on Sport Aircraft group
http://groups.yahoo.com/group/Sport_Aircraft/

Flying Gators annual Fly-in
http://www.mitchellwing.com/flying_g...annual_fly.htm