Composite Material Expertise

Guest Discussion
#1

I have been flying an A36 for 10 years. Recently I sold it and am considering an SR22. I really like what I see so far but I have no experience with composites. Some people tell me to “be careful” because “if a composite plane gets to too hot it becomes soft and loses shape”. I have looked at the SR22 POH and it talks about the paint used on the plane keeping the composite materials under 150 F. Does anyone know what happens if the paint wears off (such as might occur during lots of IFR flight) and then the plane sits on a hot Southwesten ramp where the temperature might exceed 150 F in the summer? Also has anyone had any problems with the paint wearing off and exposing the leading edges? If so what is done for this?

I talked with the folks at Lancair at Oshkosh last week and they had “tape” on one of their planes to protect the leading edges. Is this normal?

And last, does anyone have any info or references as to the wearability of composite material over time in general?

#2

Ed, people don’t like to talk about this but someone has to: My Cirrus was one of the first, but I let it out on a black tarmac in Mississippi with ambient temps about 97 and clearly a lot hotter on the blacktop. I first noticed one wing start to droop, then I noticed the entire tail sag. The plane was a write off. Only the engine and avionics were salvageable.

Seriously, that is true to the damage point. I felt the wings after the plane was in the sun for about 4 hours. All parts of the plane were cool to the touch, the tops and bottoms of the wings included. Now the insides were pretty toasty.

As to the rest of your serious questions. I have about 275 hours on my SR22 in the past 14 months. There are probably about 1/2 dozen chips in the leading edges of the wings and horizontal stabilizer. I have only been on grass taxiing, so I doubt I’ve kicked up that many pebbles. I had most fixed at the last annual with no known ill effects.

I have never had any other wear signs, but if the plane is 10 years old and the paint is getting tired, I would get it repainted regardless of whether it is aluminum or plastic.

I have not heard of any issues with the composites getting soft.

Marty

#3

Ed,
I know of many, many gliders over 20 years old that are made from fiberglass and they are still flown regularly and receive annual inspections, etc. I have also owned a glider and flown it in the southeast when it got to the high nineties without any heat related issues. And, keep in mind, glider performance degrades dramatically with any deformation of any part of the aircraft. The wings are profiled within hundreths of an inch. If they lost their shape in any way, it would be noticeable. So, the liar’s club of people saying composites loose their shape is full of $&*!.

Finally, touch up of nicks, etc is easier because there are no rivets to deal with. You can spot in a repair and then sand away the blend line with a sanding block. Can’t do that with aluminum very easily, it will bend and oil can on you.

#4

I have a 22 and live in Phoenix. It doesn’t much hotter or sunnier. We have lots of composite planes here that sit outside on the ramp. I have watched 2 Katana’s for several years at the local flight school and have seen no problems. While I would never do that to my plane because I value keeping the paint and interior from the UV damage, structurally the planes do fine.

I am convinced that composites are the only way to go.

Roger
N706CD

#5

Marty

You had me going for a while. Ha! It seems that there really isn’t anything to worry about since over 500 of the machines have been sold. But it doesn’t hurt to ask. The “old gard” is skeptical of anything new. I really want something different, up-to-date, fast and safe. The good thing is that with a sample of over 500 planes one should get just about evey kind of problem there is. Thanks for the response.

#6

The two best things to do with a Cirrus:

  1. pick it up for the first time! You’ll be smiling for days.

  2. Take a doubter for a ride. A local CFI, a charter member of the airport ‘liar’s club’ thought real airplanes were made out of metal, real pilots didn’t need parachutes and of course, auto-pilots are for wimps. (Some even though that only real airplanes had tail wheels and seat belts are for girls. but I digress, we don’t need to talk about the seniors chapter.) Anyway, before he even got the yoke he was a convert, and after, he was just looking for excuses to come for a ride.

Get yourself a ride.

Marty

#7

In reply to:

You’ll be smiling for days

I picked mine up on June 7th, I’m still smiling. People are starting to suspect things, nobody walks around smiling this long.

I have some time in a Diamond Katana. Part of the preflight check list is turning around and looking at the temperature strip that is mounted in the baggage compartment. If it indicates too high a temperature, its a no-go. I don’t think the Diamond Aircraft have this thermometer anymore, so they must have decided also that it is a non issue.

Besides, since the Cirrus has wooden spars and landing gear, it can’t be an issue.

Just kidding,Ed, about the Cirrus, but the Katana really did have the interior thermometer on the checklist.

Paul

#8

I set up the ride at Oshkosh. It happens next week. I can hardly wait.

#9

OK so what are the spars of the SR22 made of - Kevlar?

#10

In reply to:

OK so what are the spars of the SR22 made of - Kevlar?

Here’s the description from the SR22 POH:
The wing is constructed in a conventional spar,rib,and shear section arrangement. The upper and lower skins are bonded to the spar, ribs, and shear sections (rear spars) forming a torsion box that carries all of the wing bending and torsion loads. The wing spar is manufactured in one piece and is continuous from wing tip to wing tip. The shear webs (rear spars) are similar in construction but do not carry through the fuselage. The main wing spar passes under the fuselage below the two front seats and attaches to the fuselage at two locations. The rear shear webs are attached to the fuselage sidewalls just aft of the rear seats.
But that kind of skirts the issue of what the actual material is, doesn’t it?
Now it can be told! Our COPA moles have discovered that the spar is actually made of…
N O O D L E S !

#11

So far as I know the wing spar, as well as the rest of the airframe, is made of glass fiber epoxy matrix composite. When I took the factory tour all the airframe components I saw looked exactly like the green glass fiber circuit board material (FR4 board, for those in the business). I saw no use of carbon (black) or kevlar (sort of off yellow) fiber. If anyone knows anything to the contrary, please let us know.

–Frank

#12

Noodles are good. That way if you crash, you have something to eat. Thanks for the POH explaination.

#13

In reply to:

“Noodles are good. That way if you crash, you have something to eat”

And if you’re carrying termites, they can eat the landing gear struts. [;)]

#14

I don’t know about the wing spar, but I understand that the main landing gear struts are made of composite, laid up unidirectionally for maximum flexibility.

I saw the SR20 that smacked the runway at Alexander City, Alabama. It hit so hard that both mains splayed out enough to break off the brake bleeder valves. The struts sprang back with no damage.

The first time I touched a Cirrus, I was impressed with how much more substantial and solid-feeling it was, compared to the aluminum airplanes I had been flying.

-Mike

#15

Ed, I’d also like to speak to the durability issue. One of the many battles that Alan Klapmeier had to deal with when trying to secure funding was uncertainty as to the durability and repairability of the aircraft. This is still something the insurance companies are unsure of, although the fleet size and experience are rapidly easing their fears.
Anyway, Alan would take a wing section and bash the leading edge with a baseball bat. I mean bash the thing, not tap it. Other than a scuff mark, there was no deformation. Then he’d ask if anyone would like to try that experiment with a typical spam can wing. No takers. Point made.

#16

Greg

Thanks for the comments. I hadn’t thought about the gliders, but you’re right. It seemst repairs might be similiar to repairing the fiberglass fairings on Pipers. I’ve done some of that. What do you think?

#17

Gordon

Boy, is that impressive. I’m just tired of flying the same old “spam can” designs for so long. One would think that composites would have have their own issues, but from what I can tell the drawbacks are few and far between. Thanks for the info.

#18

Mike

Thanks for the input. I’m really looking forward to flying one.

#19

Thanks, Roger. That’s just the kind of input I’m looking for.

#20

Ed,
More than likely, the repairs you made were to parts that were nothing more than woven roving and resin laid up in a mold, sanded, and painted. These are non-structural parts and repairs are fairly straightforward. The Cirrus aircraft employ several different types of composite materials including a lot of foam core material for the load bearing components. I assure you, you do not want to try to repair any of those pieces without proper training and certification. If you have worked with fiberglass very much, you probably already knew that.

Anyway, finding people that are unhappy with their planes is pretty difficult, but there are a few. Overall, I’d say Cirrus leads the pack by a wide margin when it comes to customer satisfaction with the airplane and the support.