ABS Fairing and Fiberglass Repairs

kontiki

kontiki

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Kontiki
I'm looking at repairing a damaged tail cone fairing (ABS plastic) that needs to be fixed on my Grumman Tiger before I can reinstall my tail position light. It just crumbled when I opened it up.

I have a fair amount of wheel fairing (fiberglass) cracks to address sooner or later too.

I've picked through a lot of Google hits, but figured I'd see if anyone had any advice on products they stand by. Any links to good instruction guides would be good too?

I did a lot of non-structural fiberglass work years ago (on L-1011s) and it was all fine, but back then I just used whatever it was the company bought.

There are a lot of products on the market to choose from.

Thanks
 
kontiki said:
I'm looking at repairing a damaged tail cone fairing (ABS plastic) that needs to be fixed on my Grumman Tiger before I can reinstall my tail position light. It just crumbled when I opened it up.

I have a fair amount of wheel fairing (fiberglass) cracks to address sooner or later too.

I've picked through a lot of Google hits, but figured I'd see if anyone had any advice on products they stand by. Any links to good instruction guides would be good too?

I did a lot of non-structural fiberglass work years ago (on L-1011s) and it was all fine, but back then I just used whatever it was the company bought.

There are a lot of products on the market to choose from.

Thanks
Click to expand...

Somewhere around here is a thread where I fabricated some fairings from scratch. I used West System with extra slow hardener. For simple repairs I'd get slow or fast hardener (I have all three). The pump setup is really nice. I've been using part # 573 3 oz/sq yd, 38" Wide, 0.005" Thick, 60 x 58, 4H Satin Weave and 9 oz/sq yd, 38" Wide, 0.010" Thick, 54 x 18 4H Modified Twill Weave from fiberglast.com
 
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What??
You can't buy new parts for the Grumman,,, ? What the Hell :)
 
I'm a fiberglass newbie but still seem to come up with a useable part in the end. I though I had a 7 ounce 8 harness satin weave too but can't seem to find it. Fiberglast sells a sample pack so you can touch/feel/bend etc all their fabrics for pretty cheap
 
Tom-D said:
What??
You can't buy new parts for the Grumman,,, ? What the Hell :)
Click to expand...

Actually, I could buy a replacement fairing, but then the paint wouldn't match. It makes more sense to me to just repair it.
 
You can get the parts from Fletchair, but the ABS parts are repairable using a method given in the maintenance manual. If you don't have access to a copy and you're an AYA member, there is a pdf version on the website. If not a member, there is a good summary at bondline org

http://www.bondline.org/wiki/Interior_Trim

It is directed towards repairing ABS interior trim, but the manual does not differentiate between types of ABS parts.

My experience is only with interior trim. The repair was easy and looks good.

Good luck.
 
Some of these old ABS parts are so brittle they are beyond saving
 
bnt83 said:
Some of these old ABS parts are so brittle they are beyond saving
Click to expand...

For sure. One can waste a lot of time on them.

I have had some success using ABS solvent cement (the yellow stuff from the hardware store, used to glue black ABS sewer pipe joints) and fiberglass cloth. Cut the cloth so that its fibers cross the crack at 45° and all the fibers will be working for you. On a compound curve, the 45° bias will also follow the curves nicely. Clean the plastic off with MEK before cementing. Put the glass on the inside, out of sight.

Don't bother trying epoxies or polyester resins. They won't stick much, and the polyester will attack the ABS.
 
Sounds like an opportunity for some one to build a mold and start making replacement parts. real fiber glass parts.
 
The glass fairing repairs are easy, the ABS repair will likely have to be a rivet on backing plate if the plastic is old; generally not worth trying to save as the parent material is deteriorated.
 
Henning said:
The glass fairing repairs are easy, the ABS repair will likely have to be a rivet on backing plate if the plastic is old; generally not worth trying to save as the parent material is deteriorated.
Click to expand...

Yep, once the plasticizer has evaporated from the ABS, it is replacement time. The sad thing is that what should be an inexpensive replacement part costs big bucks and probably won't fit very well anyway.
 
Tom-D said:
Sounds like an opportunity for some one to build a mold and start making replacement parts. real fiber glass parts.
Click to expand...

Yep, couldn't be easier, especially starting with an ABS part for a plug. Might have to use carbon to match the weight though.
 
Henning said:
Might have to use carbon to match the weight though.
Click to expand...

Stene makes fiberglass replacement parts for Cessnas that are no heavier than the ABS. They're thinner than the ABS, are much stronger, are crack resistant, and easily repairable. And less money by a long shot.

http://www.steneaviation.com/products.asp

But nothing for Grumman aircraft.

Dan
 
The Fletchair website shows that the complete tail cone (both top and bottom halves) costs only about $205. Probably needs some trimming. Makes it hard to justify the effort of fabricating new from scratch. Maybe repairing.

The maintenance manual repair method can handle pretty badly deteriorated parts as it allows for using ABS sheet as a doubler attached with ABS cement. So essentially you can coat the inside surface of the original part with ABS cement, position pre-cut doubler sheets, clamp in place using spring clamps, and let dry. Then go back and fill in the cracks and small missing sections building up a couple of applications of ABS cement (which is just ABS plastic dissolved in solvent). Finally, paint. For tightly curved sections 0.010 inch sheets are better for following the contours. 0.020 otherwise. My experience is only with interior trim, but the shop has done a horizontal stabilizer fillet for me using the method.

My guess is that a tail cone would probably take 1-4 hours of labor over a couple of days depending upon the degree to which it had broken apart vs. being cracked but holding together.
 
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