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Bent fuel line, cause for concern?

WingnutWick

Well Known Member
Hello,

Noticed the right side fuel line in the cockpit was a bit crimped coming out of its fitting. Wondering if this is a cause for concern/needing to be fixed? 9sorry for the poor photo)

Thanks all.

Charles
 

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Could make it better

I would remake it a bit longer to get rid of that kink. I have seen one failed from being wracked like that, although it had a lot of hours on when it let go...
Besides, it's ugly.
As they say: "YMMV"
BTW, good catch.
 
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FAA guidance in AC43.13-1B says if the tube is flattened more than 75% of the original diameter, it is not usable.

The kink in that line looks terrible.
 
Page 9-18, Paragraph 9-30 (a).

Not looking to start a fight but going to opine anyway. The listed criteria appears to pertain to forming a bend, proper. This "kink" is not. If you extrapolated the curve, I'm sure you'd find it doesn't meet minimum bend radius anyway.

That's a serious stress concentration and would appear to be nothing new. Can't believe it went unnoticed.
 
FAA guidance in AC43.13-1B says if the tube is flattened more than 75% of the original diameter, it is not usable.

The kink in that line looks terrible.

"Minimum bend radii values are shown
in table 9-2. A small amount of flattening in
bends is acceptable, but do not exceed
75 percent of the original outside diameter. "

In the OP's picture, the flare has been stressed and a sharp kink in the neck.... it needs to be replaced.
 
Hello,

Noticed the right side fuel line in the cockpit was a bit crimped coming out of its fitting. Wondering if this is a cause for concern/needing to be fixed? 9sorry for the poor photo)

Thanks all.

Charles

Um...YEAH. Does that look right to you? I'd be checking all of my fuel and oil lines and such, if this was acceptable for installation in the first place by someone. No offense intended, I swear.
 
Ok so the stress is not only on the tube at the kink(though it’s highest there) the flair is stressed as well (leaks more easily) when torquing the nut high value would show but actually lower value on the flair. And flair on tube is offset. Flair fitting could also need replacement. Be careful look close at the fitting’s flair surface all around. Also look at opposite end of tube, what does it look like?

Hope this helps
RD
 
Its not rocket science----or maybe it is. IF it doesnt look like a correctly bent tube, no twists, kinks, gouges, crushed areas, mangled flares, then it probably needs to be replaced. IF you are a novice on here, look for pics of properly made tubes. There are a bunch. If you are having trouble making them, seek help. There is alot of that here too.

Just because we use a CNC bender to make our production tubes, doesnt mean that we dont use a hand bender to make a concept prototypes, or even a difficult tube that our CNC dies wont accomodate. Like this one I did recently for a RV7A with an Aerolabs gascolator. 180* bend with the flare close to the start of the bend, then a 90* vertical leg, again close to the end of the original bend. Trick was all of this had to fit in a tight area.

Use a good bender, inexpensive is fine, but take your time and practice BEFORE you attempt to make a critical tube. I have a box of various bent tubes with different angled bends just for playing around. Its easy enough to see if something is doable, than to spend a bunch of time and waste tubing trying to make something that your tool cant do.

A quick word here about 3003O aluminum tubing that is provided in Vans kits. Its relatively inepensive, and soft enough to be bent by hand, given some circumstances. BUT that doesnt mean you can kink it and then go fly. It does take some care to do properly. If you arent sure, seek some guidance
from a tech counselor, or an A&P, or even your hangar buddies. A fractured fuel line under pressure in flight is a bad day waiting to happen.

Last note---INSPECT THEM. Make sure they have proper supports and cant contact a structure or something else to cause potential damage. We've seen alot of them, even on certified planes.

Tom
 

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Should not be hard to replace and I would do it before further flight. Might be worthwhile to look at the flairs on the tubes since a builder who let that go might not be very particular about flairs either.
 
bent lines

How many people go to school and spent tens of thousands of dollars to learn something they probably wont' use in their lifetime.
Here you can spend $50.00 for an extra coil of tubing and bend away.
By the time your done, you'll be an expert.
I've bent hundreds of lines for what ever and am pretty good at it.
But, a little practice on a scrap piece (you made scrap) is good experience
I will say that line needs to be replaced before further flight.
It isn't broken now, But, a kink can crack in two minutes or never. Seen it happen.
I've had gas smell/leak in the cockpit and it isn't a good smell at 8,500 feet over the mountains.
Life is better just around the next bend. Ha Ha
My three cents worth Art
 
Thanks all.

Got a little heated eh. Thanks for all the input. For the record this is not my airplane and I am guessing that this is a recent development. The way the line sits it is subject to the possibility of being stepped on when someone gets out of the plane and bent, something that I immediately didn't like when I saw it. Of course it doesn't look right to me but I wasn't sure on the strength of the tubing under relatively low carb fuel PSIs and whether it was a: "Fix before further flight" or a "I'd change that out when you get a chance" sort of thing. That's why I came here to ask folks! Resounding "fix before further flight" - got it. Will do.

Some great info, thank you. I have done tubing work before on brakes and no, not rocket science but I certainly used spare tubing up practicing.

Does anyone use flexible fuel lines?
 
Certainly not - hence the post! Just quarrying the audience if it was a fix as soon as possible or practical scenario. That's why I come here - to learn and for sanity checks.

Um...YEAH. Does that look right to you? I'd be checking all of my fuel and oil lines and such, if this was acceptable for installation in the first place by someone. No offense intended, I swear.
 
...
Just because we use a CNC bender to make our production tubes, doesnt mean that we dont use a hand bender to make a concept prototypes, or even a difficult tube that our CNC dies wont accomodate. Like this one I did recently for a RV7A with an Aerolabs gascolator. 180* bend with the flare close to the start of the bend, then a 90* vertical leg, again close to the end of the original bend. Trick was all of this had to fit in a tight area.
...

Tom, as someone that has bent a lot of tubing and has a big scrap pile to prove it, those are some beautiful bends!
 
kinked fuel lines

I for one have mostly flexible SS with Teflon lining lines in my cockpit and under the cowl.
When I did my SDS installation with the the 6 way valve it seemed necessary. The dual electric fuel pumps have bent lines around them.
I for one have smelled fuel in bad situations and the problem was easily solved on the 'ground' with proper tools. But, I try not going there if possible.
If I'm seeing this bent line that maybe somebody "stepped on" It is going to get fixed now. And the "stepped on" is never going to happen again because of the shield I built after making the new line.
But flexible lines can get a job done with ease. Oh ya they do cost more and you can step on them if you like. Ha Ha!!!!!
Your luck may vary Art
 
Line replaced

All will be happy to know that I replaced the line today with a beautiful flex line. All problems resolved. Thanks for the input.
 
Check the other lines too

Just seeing this thread. If someone thought that line was airworthy, you might want to check the other lines/flares in that airplane.

Lenny
 
Just seeing this thread. If someone thought that line was airworthy, you might want to check the other lines/flares in that airplane.
Yeah, you’re a wee bit late to the party here, that’s already been mentioned twice… :rolleyes:
 
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