Fuel line stand-off

[Dan Thomas]

Fellow I worked with took two pairs of 6" vise-grips and brazed small jaws made of 4130 to them. Gave me one. Used it for years. Run an awl through the clamp holes, pull it all together with the vise-grips, pull the awl out and drop the screw in. Start the nut, take the vise-grips off.

 

[Timbeck2]

@JAWS I see. I was a jet engine mechanic for 10 years. I remember on the J-79 fitted with the kit for the F-4 there were a whole lot of clamps, especially around the electrical hook up for the aircraft. I remember using those clamps there but turbines are not near as leaky as a GA piston can be. I'd like to see your hacksaw blade tool.

 

[Timbeck2]

View attachment 98640

View attachment 98641

Fellow I worked with took two pairs of 6" vise-grips and brazed small jaws made of 4130 to them. Gave me one. Used it for years. Run an awl through the clamp holes, pull it all together with the vise-grips, pull the awl out and drop the screw in. Start the nut, take the vise-grips off.

We use that often. First thing to do is dull the awl unless you want a few puncture wounds.

 

[Capt. Geoffrey Thorpe]

We use that often. First thing to do is dull the awl unless you want a few puncture wounds.

NOW you tell me.

 

[Timbeck2]

NOW you tell me.

Only took four or five good bleeders until I got the file out.

 

[JAWS]

@JAWS I see. I was a jet engine mechanic for 10 years. I remember on the J-79 fitted with the kit for the F-4 there were a whole lot of clamps, especially around the electrical hook up for the aircraft. I remember using those clamps there but turbines are not near as leaky as a GA piston can be. I'd like to see your hacksaw blade tool.

 

[wilkersk]

The black braided line is fuel. It was contacting the spark plug wire bundle and looked to be wearing the wire insulation. Is this a possible fix? I’ve heard it’s a no-no to connect fuel lines to wiring.

View attachment 98446

2 comments:

1. I've used zip-ties in just such a way on tube and fabric aircraft where wire bundles run along a longeron tube or cross-member on experimental aircraft. But, there's always some anti-chafe tape under the zip-tie. And, I never use nylon zip ties forward of the firewall.

2. Although I can't see enough of the fuel line or sparkplug wires, I suspect there is some non-traditional routing going on there. There should definitely be some space between the fuel line and sparkplug wires. Sometimes the desire to use the minimum length of fuel line (for whatever reason) leads to problems like this.

 

[Stewartb]

Tying wires to tubes? OMG, say it ain’t so!

 

[Dan Thomas]

Tying wires to tubes? OMG, say it ain’t so!

View attachment 98673

Tying wires to tubes that vibrate is bad. Or wires or hoses that vibrate, to tubes.

Some of those in the picture are crossing the tubes at 90°. A single tie there puts its edges against the wire, which can damage the wire. I also see wires tied to fuel lines there.

 

[BoButt]

For some reason unknown to me, when a soft material is allowed to chaff on hard material, the hard material will suffer. Standard zip ties can quickly damage motor mounts if there is any motion between the two. A cushion preventing motion is best practice if one insists on using zip ties. Properly fitted and installed Adel clamps are best. Koraseal lacing is a lost art and very expensive but something we used on the twin beeches and DC3s I used to service before I knew of zip ties.

 

[BoButt]

Tying wires to tubes that vibrate is bad. Or wires or hoses that vibrate, to tubes.

Some of those in the picture are crossing the tubes at 90°. A single tie there puts its edges against the wire, which can damage the wire. I also see wires tied to fuel lines there.

Maybe those are temporary prior to properly being secured!

 

[wilkersk]

Maybe those are temporary prior to properly being secured!

That's what I was thinking. Also, I'm wondering how that would be covered?

 

[Dan Thomas]

Before the invention of the nylon tie, tape was used. The old, fabric, black, sticky gooey stuff. Like the hockey stick tape when I was a kid. Sometimes it was white tape. And often the tape was wrapped around the tubing once or twice first, then the wire laid against it and the tape run around a few more times. The tape didn't slip and grit didn't get under it. Age would dry out the adhesive, though. But age embrittles nylon ties, too.

Now we have what some call "rescue" tape. Silicone tape that sticks mostly to itself and not much else. Run that around the tubing, lay the wire on it, and a few more wraps does it. Stretch it a bit as you go. It stands heat and cold and its tension keeps it in place and grit doesn't get under it.

 

[Stewartb]

That's what I was thinking. Also, I'm wondering how that would be covered?

Like it’s supposed to be covered. How would you do it? Since you’re all critics I assume you all have pics of your last build showing how you did it, right?

Do you know what I won’t use? Tape. Corrosion happens under tape. Corrosion is the enemy of any tube and fabric airplane. I’m much happier with nylon zip ties. They aren’t hard enough to etch my powder coat, let alone the tubes. The stuff you read on the internet isn’t always true.

 

[wilkersk]

View attachment 98722
Like it’s supposed to be covered. How would you do it? Since you’re all critics I assume you all have pics of your last build showing how you did it, right?

Do you know what I won’t use? Tape. Corrosion happens under tape. Corrosion is the enemy of any tube and fabric airplane. I’m much happier with nylon zip ties. They aren’t hard enough to etch my powder coat, let alone the tubes. The stuff you read on the internet isn’t always true.

Not criticizing. You put the picture up, and I was just wondering what else went over the keel before the fabric.

And, I've been using fusible tape, for as long as I've been in aviation, and if applied right, it is not corrosion prone. But, I have seen nylon zip ties chafe metal tubes, and I've seen them become brittle from heat and age, and then fail, allowing things to move and chafe where they shouldn't.

 

[455 Bravo Uniform]

@Stewartb @Dan Thomas @wilkersk
And others who asked, this will give you more of an idea of the current layout:



I never thought this thread would cause such input/opinions. Appreciate it.

 

[Dan Thomas]

@Stewartb @Dan Thomas @wilkersk
And others who asked, this will give you more of an idea of the current layout:

Pretty hard to do much else with that.

 

[FastEddieB]

I’m sure that the conventional hose clamp will do the job, but I’ve heard it offered that smooth F.I. clamps are a slightly preferred choice.

 

[mondtster]

I’m sure that the conventional hose clamp will do the job, but I’ve heard it offered that smooth F.I. clamps are a slightly preferred choice.

Most I’ve seen don’t have any clamp. The hose in question is a vent line. But I agree, a worm clamp like that is the last thing I’d use. I’ve probably worked on too much european stuff but my preference would be an Oetiker clamp if I used anything.

Knowing that it’s the vent line I probably wouldn’t have done anything with the hose. That’s probably the reason none of the mechanics working on it before bothered messing with it.

 

[bluerooster]

Us experimental guys have been using that trick for a long time.

Don't know how they do it for certified planes but I was taught to keep fuel and fire separated by at least six inches and never place fuel above fire. FWIW I like as much separation as I can get so what was done here would not be acceptable to me.

AC No: 43.13-1B gives information to answer these type of questions. In there I read:
"In no case should wiring be supported by the fuel line."

Download a copy here:

https://www.faa.gov/documentLibrary/media/Advisory_Circular/AC_43.13-1B_w-chg1.pdf

Would be handy if you would also post the specific page.

That said, the AC cited is a wealth of information.

But the
"In no case should wiring be supported by the fuel line." line quoted has naught to do with the OP question. He's not supporting wireing by the fuel line, but just making separation. (assuming they are independently supported) But I would seriously consider re-routing the fuel line in such a manner that it is independently supported, and does not come in contact with anything. But I'm sort of anal about hoses, (both electric, and fluid) and abrasion.

 

[Daleandee]

Would be handy if you would also post the specific page.

That said, the AC cited is a wealth of information.

But the
"In no case should wiring be supported by the fuel line." line quoted has naught to do with the OP question. He's not supporting wireing by the fuel line, but just making separation. (assuming they are independently supported) But I would seriously consider re-routing the fuel line in such a manner that it is independently supported, and does not come in contact with anything. But I'm sort of anal about hoses, (both electric, and fluid) and abrasion.

Seeing as how we are assuming (yep we know what that means) I also think that one not supporting the other means not tying them together i.e. separation. I've been taught that fuel and fire should always be separated and the fuel lines should never be above electrical wiring. Maybe it's just a safety thing with me as I've seen others do this and when it's pointed out they usually see the danger.

As for the reference in AC-43.13-1B or most any other document I press Ctrl+F on the keyboard and type in the wording I'm searching for ...

 

[Stewartb]

Not criticizing. You put the picture up, and I was just wondering what else went over the keel before the fabric.

And, I've been using fusible tape, for as long as I've been in aviation, and if applied right, it is not corrosion prone. But, I have seen nylon zip ties chafe metal tubes, and I've seen them become brittle from heat and age, and then fail, allowing things to move and chafe where they shouldn't.

No heat or UV exposure where my zip ties are shown. What is there? Moving cables in close proximity to hard fuel lines and wire. I don’t want anything to move and I can’t think of a better solution than high quality nylon zip ties. Secure and permanent and I expect they’ll outlast me. Inside the engine cowl I use rib lace to secure wires. No zips where heat is expected. The zip ties in my photo are fixing lightweight wires so they won’t drum on the fabric. Very low stress. Maybe someday I’ll open up the inspection rings and look but there’s no need in the near future, and that’s a testament to using appropriate materials for the job.

On my landing gear? GripLocks are a great example of a modern materials solution to an old problem.

 

[Dan Thomas]

Seeing as how we are assuming (yep we know what that means) I also think that one not supporting the other means not tying them together i.e. separation. I've been taught that fuel and fire should always be separated and the fuel lines should never be above electrical wiring. Maybe it's just a safety thing with me as I've seen others do this and when it's pointed out they usually see the danger.

As for the reference in AC-43.13-1B or most any other document I press Ctrl+F on the keyboard and type in the wording I'm searching for ...

That setup we see is the typical fuel-injected installation and there isn't much you can do to reroute that fuel line. If you made a longer hose and ran it under the ignition leads, it would be too close to the hot cylinder heads and create even more hot-start issues. And the hose would age much faster.

If someone made a bracket that attached to the ignition wire and fuel injector line support bracket you see there, it would have to be fairly tall to attach the fuel line via an Adel clamp. Now we'd have a tall, skinny bracket that will vibrate and maybe fail, and we're also putting more vibratory stress on the ignition /injection line bracketry. It's already pretty light stuff.