Undersize SCAT duct from ACS?

[Harold Lanfear]

Has anyone else had problems with undersize SCAT tubing from AC Spruce? Last fall, I bought some 2" SCAT and just got around to fitting it and it doesn't fit over the 2" Aluminum fittings. The other SCAT I have fits fine. The old stuff also has Aeroduct printed on it, where the new stuff does not.

As best I can measure this, its about 0.010" smaller than the old stuff I have.

I sent a note to ACS today, hopefully they will have a decent explaination but after the thread on fittings, I'm hesitant.

[Brian Denk]

I remember wrestling with that stuff years ago. So, it's not a problem with a current batch as far as I can tell, but par for the course. I just about ripped the silicone material apart trying to jam it up onto the cabin heat box flanges. You'd think they would put a few thousandths extra diameter so they will actually slide over a 2" nominal flange! It appears they are a "net fit"...no more, no less.

Ain't it fun?

[AlexPeterson]

SCAT is really miserable stuff. The doggone wire in it is ornery, and what you have observed in the tight fit seems typical.

Does anyone have any tried and true tricks for beating the stuff into submission?

[Ironflight]

Originally Posted by AlexPeterson

Does anyone have any tried and true tricks for beating the stuff into submission?

I don't think there's anything special about my technique - was taught it many years ago by an A&P, and while it doesn't just jump on by itself, it seems to work OK. I cut the SCAT about an inch longer than I need to make sure I have extra, then pull the last two coils (or so) of wire loose from the inside. Snip off the excess, leaving about a half a turn loose inside, and give it just a slight kink "inboard", then push it back into the tube. You end up with about an inch of the fabric/silicone tube at the end, with no wire in it - this stretches pretty well over the flange. I've never had one come off, or have the wire poke through (the one thing that I thought might happen), and have had ends done this way on my airplanes last 20 years.


Paul

[RV7Guy]

Seemed to work on other tubing and stuff so while battling the SCAT tubing I used my heat gun (actually a heat gun used for model airplane covering material) to heat the tubing slightly. Somewhat surprisingly it worked fine to get over the fittings.

I agree, with Brian, why can't they make the stuff a little larger? This is one place where a tight fit isn't that much fun.

[gmcjetpilot]

Originally Posted by Harold Lanfear

Has anyone else had problems with undersize SCAT tubing from AC Spruce? Last fall, I bought some 2" SCAT and just got around to fitting it and it doesn't fit over the 2" Aluminum fittings. The other SCAT I have fits fine. The old stuff also has Aeroduct printed on it, where the new stuff does not. As best I can measure this, its about 0.010" smaller than the old stuff I have.

Hummmmmmm, sounds like the non AN fitting thread last month. May be they are using SCAT from China?

http://www.vansairforce.com/communit...fitting+spruce

[Harold Lanfear]

Thanks guys for the tips; I'll try the heat and/or the remove wire ones both. What got me is that I'd never had a problem with it before. In any case, I know VAF can always provide some ideas. H

[AlexPeterson]

Originally Posted by Ironflight

I don't think there's anything special about my technique - was taught it many years ago by an A&P, and while it doesn't just jump on by itself, it seems to work OK. I cut the SCAT about an inch longer than I need to make sure I have extra, then pull the last two coils (or so) of wire loose from the inside. Snip off the excess, leaving about a half a turn loose inside, and give it just a slight kink "inboard", then push it back into the tube. You end up with about an inch of the fabric/silicone tube at the end, with no wire in it - this stretches pretty well over the flange. I've never had one come off, or have the wire poke through (the one thing that I thought might happen), and have had ends done this way on my airplanes last 20 years.
Paul

Paul, thanks. I will do this next time. So, the wire doesn't overlap the tube onto which we are putting the scat? I guess I thought the airplane would fall right out of the sky if the wire wasn't over the tube.

[grjtucson]

I am on the fuselage and have never had any experience with Scat tube installation or flanges for that matter...

...which means I'm just fishing for knowledge to prepare for the future.

That said, is there any reason you couldn't just flute the flange a bit to reduce it's size enough the the Scat with wire included would fit over it? I'm assuming you'd then use some sort of high-temp RTV and a big 'ol hose clamp as well.

Just an idea, and hopefully one that will lead to me to being steered straight.

George

[Davepar]

Just a general tip on SCAT tubing. I battled with the stuff for hours until I discovered soapy water.