Fordnatics List Archive

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Mail From: (email redacted) (Neil Narwani)

Hi,

Yesterday I went to one of these aircraft places and had them cut and
re-flare the steel tube with a stainless tube nut and sleeve. I tried
that last night with the alum. reducer. It still leaked. So I figured
that I'd get the steel reducer today, but when I went to talk to them
again, both they and another two places said that the problem isn't
with the fittings, but that the steel tube (the little piece from the
stock fuel line) had a seam on it (which is visible on the inside of
the tube) which is making the flare not seat properly.

The best suggestion I got was to use a bit of 'gasket-seal' compound
to try and absorb the difference between the flare and the flare-seat
on the reducer. I guess I should do this very carefully, so it doesn't
get sucked into the tube. I'll try that tonight. In the meanwhile,
I was thinking however...

1) Couldn't I get another 5/16" tube without a seam, and join it to
the current problem piece with a short piece of 5/16" hose and a
pair of hose clamps? I could then flare the other end of the clean
tube and all should be well, right?

2) Couldn't I just weld the flared-tube to the reducer? I can still
remove the other side of the reducer if ever necessary.

3) Couldn't I use JB-weld (really solid epoxy) to permanently join the
the flared-tube with the reducer? Of course I'd have to be real
careful not to spill some in the tube accidentally and block off
the hole.

Help, please! I'm getting desperate/super-frustrated.

Thanx,
-Neil.


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This read-only message was archived from a public mail list.
Mail From: (email redacted) (Scott Griffith, Sun Microsystems Lumpyware)

On Sep 14, Neil Narwani wrote:

> Yesterday I went to one of these aircraft places and had them cut and
> re-flare the steel tube with a stainless tube nut and sleeve. I tried
> that last night with the alum. reducer. It still leaked. So I figured
> that I'd get the steel reducer today, but when I went to talk to them
> again, both they and another two places said that the problem isn't
> with the fittings, but that the steel tube (the little piece from the
> stock fuel line) had a seam on it (which is visible on the inside of
> the tube) which is making the flare not seat properly.

That's why you want to use that particular flaring tool I recommended.
It puts a circular burnish on the tube ID, and takes care of ridges
and imperfections on the mating surfaces. It's actually pretty good at
making even really crummy seamed tubing (like the never-to-be-
sufficiently-damned Ford OEM brake tubing) flare and seal well. Sounds
like the tool they used is a straight, non-burnishing 37deg flaring
tool. Too bad.

> The best suggestion I got was to use a bit of 'gasket-seal' compound
> to try and absorb the difference between the flare and the flare-seat
> on the reducer.

Yuck. But if it's the only way you can do it, I guess that it'll have
to do. The whole reason to use the AN stuff was to do the job right,
though, and it seems damned sad to then kluge around the edges. The
only gasket-seal stuff I would even try in that case would be Loc-Tite
Gasket Eliminator #518, which is an anaerobic sealer, and I'd let it
sit overnight to cure before pressure-testing it. This is a last-ditch
deal, though, because you'll have hell cleaning it out of the fittings
if it _doesn't_ work. And I'd give it about a 50-50 chance.

Don't use silicone, or some other stuff. It needs to be fuel
resistant, or it'll _seem_ to seal, for about the first 2 or 3
hours...

> 1) Couldn't I get another 5/16" tube without a seam, and join it to
> the current problem piece with a short piece of 5/16" hose and a
> pair of hose clamps? I could then flare the other end of the clean
> tube and all should be well, right?

Then you might as well use rubber hose and clamps and skip the AN
stuff altogether. And I would most strenuously urge you _not_ to do
that. 50psi fuel, pressure cycling, and cold-flow of the rubber hose
within the clamps _will_ lead to leaks. The only question is *when*,
not if...

> 2) Couldn't I just weld the flared-tube to the reducer? I can still
> remove the other side of the reducer if ever necessary.

Sure. But in that case, the right thing to do would be to just use a
weld-on 6AN male bung, and eliminate the reducer altogether. You could
probably just slip the bung over the OD of the tube and braze it in
place. This is probably the strongest answer of all, but it is a pain
in the butt. As if what you've been through so far _isn't_...

> 3) Couldn't I use JB-weld (really solid epoxy) to permanently join the
> the flared-tube with the reducer? Of course I'd have to be real
> careful not to spill some in the tube accidentally and block off
> the hole.

I wouldn't. Even JB-weld (which is pretty good stuff, as kluge
materials go) is a long way from optimal, or even safe, to use
immersed in fuel at 50psi with thermal and pressure cycling. Once
again, the only question to answer would be _when_ it would fail, not
if.

Is there any chance you could get the female die collar for the
Rol-Aire tool around that tube, and just use the ram to burnish the
flare? Might be worth a try, anyway. Don't enlarge the flare, just
seat it against the taper in the female die, and then run the ram down
and burnish it. You'll need that steel reducer. You can mix steel and
stainless, but the sealing surface on that soft aluminum reducer has
been scarred up enough by the seam that it's now scrap, most likely.
The steel reducer is *much* more likely to win!

-skod

- --
Scott Griffith, Sun Microsystems Lumpyware
expatriate SCCA New England Region Flagging/Communications worker
(and driver, of anything that turns both right and left,
and can pass tech...) Return Path : (email redacted)