How is Your Stits/Polyfiber Holding Up?

[Steve Pierce]

Did a pre-purchase on a 135 hp Piper Colt yesterday that was covered in Stits in 1997 and finished in Poly-tone. The cover job looked very professional and the finish didn't appear to be real thick but it had cracks in the finish at the trailing edges, behind the fuel tank cover, fuel tank ribs and leading edges of the horizontal. I covered a set of L18C wings the winter before last and the trailing edges of the wing had cracks the following winter. I talked to Jon Goldbaum (Poly-Fiber owner) and he said I should have used wider tapes at the trailing edge to create double fabric past the metal trailing edge. Upon inspection I found I had tape past the metal. I was wondering if anyone else has had this problem? I don;t want to start a discussion on different process just one on trials and tribulations of Stits/Polyfiber. Thanks.

 

[cubunltd]

Steve,
I've been using Poly-Fiber for 12 years now and none of my aircraft have the cracking problem you describe. However, I've been using PPG as a top coat, Durethane at first and then Delta when Durethane was discontinued. I started using the PPG before Poly-Fiber changed the STC, but I've recently been getting field approvals to use PPG as a top coat. The Durethane and Delta(DGHS) was formulated by PPG for fabric aircraft.
I also use 3" tape at the trailing edge so it extends just past the metal.
What top coat are you using and how many coats?

P.S. I haven't forgotten about the tank straps. I had to round them up and I have 2 sets for you. Looking for a box to put them in. Will probably ship right after Christmas if that's ok.
cubsunlimited@verizon.net
cubsunlimited.com

 

[Steve Pierce]

I used 3 coats of white Polytone on the L18C wings. That is the only thing I have covered with Stits that I have gotten cracks in.

 

[cubunltd]

Check my original reply, I edited it.

 

[Steve Pierce]

Thanks.

 

[bear bait]

Steve
I covered my 12 in 1997 with poly tone. I used the stits method all the way including three coats of poly tone. I have several places where there are cracks. I had leaky fuel tanks several times. The fuel really ate up the fabric and I replaced it around the tank area when I installed Atlee's 30 gallon tanks. Under the wings where the fuel ran down the fuselage is a streak and cracked area. But I also have cracks where there was not any gasoline, along the lower longeron and along the formers. I thought maybe I had put the poly tone on too thick. I won't use poly tone on anything I build for myself again.

 

[D. Davis]

Hi Steve,
When I rebuilt my cub I used Stits and finished with Poly Tone. I bought
all the covering supplies at once. That was a bad idea because it took longer to rebuild that I had expected. Finishing up with Poly Tone that is hovering around the expiration date had me a little concerned. I applied three/ four top coats and the finish seemed ok. That was in the mid nineties, Now I'm thinking about rejuvenation because I have the cracking
you describe. I think the elasticizers in the paint had diminished toward the end of the expiration date. Maybe that is the case with the Colt.
Dave.

 

[glassjet]

I'm sure it has been discussed in the past.... But I like dope cause you can rejuvinate it every 10 years and it looks pretty good.... very functional and very easy to repair... I have had good luck getting a nice shine by using 20% dope and 80% thinner on my last 2 coats..... I have a friend wanting me to go with aerothane on my cub... but I am afraid of cracks that will be alot of work down the road..... I plan on a total rebuild in 7 years anyhow.. so maybe it won't be a big deal..

 

[cubunltd]

glassjet.
read my prior post. I've used stitz with the PPG product for over 12 years and no cracking. I actually demonstrate the flexability of the paint by poking my finger hard into the side of the fuselage at flyins on a 10 year old paint job. you should see the look on the faces when I do that. I now have to get field approvals to use the PPG because of the change in poly-Fiber's STC. I have also been in contact with Poly-Fiber and they are considering allowing the PPG product. You don't have to rejuvenate and the paint is pretty much chemical proof. Won't burn like Dope.
cubsunlimited@verizon.net

 

[WhiskeyMike]

Fabric trouble

I am sure there's a thread on this---but someone used that water process on my elevators, and now the paint on one section is crumbling, and there's no sort of silver underneath. What on earth am I gonna do -- short of recover, which I really don;t want to do???

Many thanks for some practical advice.

 

[glassjet]

Can you get down to the bare fabric? If you can... you can probably re-apply the process...... is that the blue river 7600 you have? I think there is an AD out on that particular process.....

 

[bob turner]

I bet recovering tail surfaces is a lot easier than stripping. Hardest part is those two tubes that get frozen into the horizontal stabilizer halves.
Fabric on gear legs used to crack along the tubes. All of them cracked - Stits, Ceconite, and Air Tech. Cure here in the warm country was 101 Ceconite, 101 tapes, and dope finish. No cracks.

 

[pzinck]

Blue river

I had a maule some years ago.We took the razorback off and the guy covering it reccomended the blue river stuff.What a mistake.Just horrible.Are they out of business?What about razorback? What happened to that process? After that ordeal i seriously thought about metal planes.

 

[cubscout]

Re: Blue river

What about razorback? What happened to that process?

Well, I inherited a razorback-covered PA-25 to run and maintain, through no fault of my own. Form 337 circa 1984 or so by Mr. Sam Macre himself, the inventor of the process; had a good forthright conversation with Mr. Macre ~7 years ago, too. With no disrespect, this was an innovative thing in the late '50's or so when invented, but not what you want to do now.

This is a pre-preg fibreglass process, with Butyrate dope. The fabric itself is inert, doesn't even require punch-test, per the FAA approvals. Problem is, the butyrate plasticisers eventually get brittle. Same problem as with the Ceconite process. Despite very good workmanship, lots of ringworm showing up, especially wherever the fabric touches metal, i.e., lower longerons, inboard wings....

You really need to get the fabric off every 20 years or so to see what is lurking underneath, especially on a working Supercub, or something which has Agricultural Application history. (Hint: If you can smell pesticides, there's corrosion. If you CAN'T smell pesticides, you've been around them things too long)

Pawnee's still not as bad as most of the newer Razorback-covered Maule's I've seen, but needs to be addressed. Most of the Maules I've seen in recent years had at least the controls, and usually the fuselage recovered.

May try some rejuvinator on the Po'ny when things warm up.

As far as I know, Razorback no longer available.

I've had great experience with both Stitts/Polyfiber (Polytone colour coat) and Ceconite with Dacproofer under C.A.B., but workmanship probably more important than the process used.

Just my limited experience. Cubscout

 

[harneymaki]

Might be off-topic, but........................... I saw this a week ago.


RAZORBACK FABRICS, INC.

We Produce a glass fabric for covering the flight controls of the DC-3 and its variants.

We also have a fabric shop that will apply the fabric to the flight controls and exchange them with any serviceable frames.
Our fabric is glass and is permanent, to the point that no punch test is needed nor reccomended.

OUR PRODUCT HAS BEEN ON THE MARKET SINCE 1960
AND MOST OF THOSE CONTROLS ARE STILL IN SERVICE
ON DC-3'S AND B-18'S.

RAZORBACK FABRIC IS MADE OF PURE GLASS, NO EPOXY OR POLYESTER, AND WILL NOT BURN, FADE, DETERIORATE IN UV OR ROT. INEXPENSIVE BUTRATE DOPE IS USED TO GLUE, TAUTEN AND FINISH THE FABRIC TO THE STRUCTURE, AND IT WEIGHS LESS THAN THE ORIGINAL GRADE A COTTON.

IT IS THE ONLY SYNTHETIC FABRIC AUTHORIZED
BY THE AIR FORCE AS QUOTED BY T.O.1-1A-11.

TO FIND OUT MORE, CALL US ANYTIME AT:

RAZORBACK FABRICS, INC.
1-870-647-2622
OR
Email us at:


RAZORBACK FABRICS, INC. e-mail address has changed to:
razorbac@tcac.net

Our prices for all flight control exchanges is $2000.00 each.
We deliver for $1.00 per mile one way.
Our fabric is FAA-PMA'd, STC'd, ISO 9002 and so permanent that it does not require
any annual "punch tests" to remain airworthy as all other fabrics do.
Thank you. Robert Little

 

[arcticflyr]

Steerman, if those are covered in the 7600 process, get it off there NOW. I bought all new tail surfaces for my cub after being lured into to blue mountians hype in the 80's. They had wicked rust going on.

 

[alex]

stits

Howdy Steve,

I have the same problem you describe in the same areas. I used the light grade tapes. 2001 when I recovered my PA-11. The fuselage is still perfect, like the day I finished. I am going to try a wider tape when I repair.

Alex