Composite Aircraft in the long term...

On Wed, 03 Sep 2003 13:01:42 GMT, Jay Honeck wrote:
Reason for asking: A long discussion with some pilots who were staying at
the inn, who contend that they just won't last. Using as an example the
fiberglass wing tips and cowlings that always crack, flake, and crumble
after 15 years, requiring costly (and usually unsuccessful) repairs, these
pilots are convinced that the composite material in Cirrus will eventually
behave in much the same way. And once your fuselage parts start to crack,
flake, and delaminate, the planes will become essentially large
paper-weights.

Our flying club in Houston had an old Arrow 1. The cowling was still in
good (but not perfect) condition. The cowling is in a hostile place -
baking hot engine. The structure of the fibreglass was sound. It had
been around since the 1960s.

As others have noted, plenty of old fibreglass gliders are still beautiful
today. Take care of the paintwork and the composite Cirrus will last too.
You need to take care of the paintwork on a metal plane too (or they
corrode, especially where I live, right next to the sea).

You can't really compare Piper's crappy cowlings from the 60s to the
processes used to make the Cirrus/Lancair/Diamond aircraft today.

--
Dylan Smith, Castletown, Isle of Man
Flying: http://www.dylansmith.net
Frontier Elite Universe: http://www.alioth.net
"Maintain thine airspeed, lest the ground come up and smite thee"

Jay Honeck wrote:

So what's the group-think here? Will we by flying used Cirrus' in 20 years?

I still see a fair number of antique Corvettes on the road.

George Patterson
A friend will help you move. A really good friend will help you move
the body.

Composite gliders have been around for over 40 years with an excellent
record for structural integrity. My Glasflugel H301 Libelle glider,
N301BW, will be 40 years old in 2004. Made of plain 'ol E glass and
epoxy. Closing in on 3000 hours of flying time, still looks and performs
great. Very few AD's, all on the metal parts.

I have owned and flown old wood, old metal, and old glass. I have had
more problems with the metal than the wood and glass put together.
Corrosion and fatigue. Probably because people are more likely to take
care of wood and plastic and to neglect metal. Fabric covered aluminum
wings are probably the worst for this. Often left sitting out for years
with moisture collecting in wing, not to mention rodent urine, etc. Seen
aircoupe spars that were little more than aluminum oxide powder.

One thing about old glass: Old fiberglass aircraft were significantly
overbuilt to get some rigidity out of the very flexible fiberglass.
Hence, my glider has a 9.5 g wing just to make the wing stiff enough to
keep both tips from drooping to the ground when it's not flying. Carbon
is stiff enough that you can build a stiff structure that is still
pretty weak.

Composite materials tech and fabricating methods are advancing at a high
rate. Eventually, new metal airplanes are going to get rare (says the
guy who just bought a bunch of steel tubes, rags, and sticks with a late
40's Continental to drag it through the air).

In a previous article, Foster said:
Paul Tomblin wrote:

Looking at the 5 Pipers on our flight line
(http://www.rochesterflyingclub.com/f...equipment.html), (and the four
aircraft that we've sold in the time I've belonged to the club) I'd have
to say that Piper wingtips, wheel fairings and cowls are made with
possibly the worst grade of fiberglass ever made.

That's why they're so cheap to replace. ;-)

No, that's why we've got a pair of LoPresti Zip Tips waiting for us when
we take the Dakota to Goderich to get repainted this fall. We're not
wasting another dime of Piper crap fiberglass.


--
Paul Tomblin , not speaking for anybody
It could have been raining flaming bulldozers, and those idiots would have
been standing out there smoking, going 'hey, look at that John Deere burn!'
-- Texan AMD security guard

Paul Tomblin wrote:

Looking at the 5 Pipers on our flight line
(http://www.rochesterflyingclub.com/f...equipment.html), (and the four
aircraft that we've sold in the time I've belonged to the club) I'd have
to say that Piper wingtips, wheel fairings and cowls are made with
possibly the worst grade of fiberglass ever made.

That's why they're so cheap to replace. ;-)

Jay,

The composites used on Cirrus are not anything close to the fiberglass
material you describe. The better comparison is to look at composite
sailplanes that are twenty and thirty years old and have no problems.
The UV issue was dealt with 20 years ago as well.

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.

Warmest regards,
Rick

"Jay Honeck" wrote in message news:WCl5b.344377$uu5.68896@sccrnsc04...
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?

Reason for asking: A long discussion with some pilots who were staying at
the inn, who contend that they just won't last. Using as an example the
fiberglass wing tips and cowlings that always crack, flake, and crumble
after 15 years, requiring costly (and usually unsuccessful) repairs, these
pilots are convinced that the composite material in Cirrus will eventually
behave in much the same way. And once your fuselage parts start to crack,
flake, and delaminate, the planes will become essentially large
paper-weights.

So what's the group-think here? Will we by flying used Cirrus' in 20 years?
Or will they all be scrap by then?

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

A good place to start looking at longevity is the Slingsby T-3. It is
probably the one aircraft out there that is really accumulating hours
at a rate with reliable and exacting maintenance standards, that will
give you a good idea. So far it has been a big bust in the training
program for the USAF. It is the only aircraft that I have ever seen
that has a structural temperature limitation. If the structure is over
a certain surface temp, it is prohibited from flight due to structural
degredation at the elevated temp. With the big engine, it is extremely
temp sensitive under the cowling and has what appears to be massive
vapor locking problems despite using multiple fuel pumps. The problems
with the a/c power and structure have become so problematical, that
the USAF grounded the fleet and will probably destroy the a/c rather
than let them get into civilian hands. I know it's only one aircraft,
but the design is certified at a minimum to FAR 23 standards.

What is interesting, is the a/c that are built to the same TC, and
using the smaller engines so far don't have the same problems. Even
those that are in military training programs outside the USAF don't
have the same fuel and structure problems that I've been able to find.

Craig C.

"Craig" wrote in message
om...
A good place to start looking at longevity is the Slingsby T-3. It is
probably the one aircraft out there that is really accumulating hours
at a rate with reliable and exacting maintenance standards, that will
give you a good idea. So far it has been a big bust in the training
program for the USAF. It is the only aircraft that I have ever seen
that has a structural temperature limitation. If the structure is over
a certain surface temp, it is prohibited from flight due to structural
degredation at the elevated temp. With the big engine, it is extremely
temp sensitive under the cowling and has what appears to be massive
vapor locking problems despite using multiple fuel pumps. The problems
with the a/c power and structure have become so problematical, that
the USAF grounded the fleet and will probably destroy the a/c rather
than let them get into civilian hands. I know it's only one aircraft,
but the design is certified at a minimum to FAR 23 standards.

What is interesting, is the a/c that are built to the same TC, and
using the smaller engines so far don't have the same problems. Even
those that are in military training programs outside the USAF don't
have the same fuel and structure problems that I've been able to find.

Craig C.


The Slingsby's problems are not composite related. They are engine/fuel
system related.

Some (all?) of the Diamona's (sp?) have structural temp limitations as well.
That's why they paint 'em white. Also, the folks who live in Phoenix or
other places that have extreme temperatures often keep 'em hangared.

KB

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