Need to replace a section of solid steel brake line in my RV-7 due to chafing...

[donmtt]

Long story short, the right brake line that crosses under the engine was chafing on a clamp for the last 20 years - and it's now leaking. After looking things over, I think the best course of action is to cut out the damaged section (about 2 feet), plumb in a steel braid segment and adapt it to the remaining steel line. (See photos.) The main reason for this is the fact that I can't remove the gear leg fairings and they look to be foam-filled. (I bought the plane build in 2006 last year.)

Would love some feedback.

 

[Desert Rat]

Long story short, the right brake line that crosses under the engine was chafing on a clamp for the last 20 years - and it's now leaking. After looking things over, I think the best course of action is to cut out the damaged section (about 2 feet), plumb in a steel braid segment and adapt it to the remaining steel line. (See photos.) The main reason for this is the fact that I can't remove the gear leg fairings and they look to be foam-filled. (I bought the plane build in 2006 last year.)

Would love some feedback.

Those brakes lines aren't steel, they're just soft aluminum. When built, it comes in the kit as a roll and the builder cuts off a length, bends it by hand, and flares the ends. It would be pretty easy to cut out the offending section, install a union and then take the new piece all the way to the firewall fitting. You'd need a tubing cutter which is the same one you can buy at Home Depot for copper plumbing line. You'll also need an aviation specific flaring tool. The flaring tool MUST be aviation specific because it makes the flare at a different angle than normal plumbing ones in order to fit aircraft AN hardware. Then bleed the brakes.

If that's not in your skillset, and A&P should be able to knock it out without too much fuss.

However you do it, you should get rid of those zip ties that are holding the line cinched up against the engine mount and replace them with adel clamps. Dirt and crud will get under those and act like sandpaper. Over time they've been known to wear grooves in the engine mount, which is obviously a big deal.

Also, if it were me I'd get rid of the foam inside the leg fairings. I don't like the idea of filling those up because who knows what sort of corrosion you could have going on underneath on the gear leg that you'd never be able to see or remediate. If you take the foam out, you can do a new brake line start to finish with no splices. If it's just expanding spray foam I think acetone will dissolve it.

edit- I just noticed in one of your pix that if you get rid of the foam, you'll have to add a tab on top of the fairing. Per plan, that faring is positioned and secured by a tab at the top that's held to the gear leg with a radiator hose clamp.

 

[rockyfatcat]

I would replace the entire length of brake line.

I bought a project -7 that had a number of issues including fairings and brake lines. I ended up buying new gear leg fairings and a braided brake line.

You have already identified a brake line that was damaged by being improperly secured, and the foam filled fairing is only going to prevent inspecting the hidden components for damage or corrosion.

 

[RNB]

Tsflightlines could likely have this to you in 2 days if need be.

 

[donmtt]

Thank you! I'm told that the gear leg fairings may be held on via piano hinge so I need to check for that. To my eye, they looked un-removable (though in my heart I know that can't - or at least shouldn't - really be the case).

 

[donmtt]

Those brakes lines aren't steel, they're just soft aluminum. When built, it comes in the kit as a roll and the builder cuts off a length, bends it by hand, and flares the ends. It would be pretty easy to cut out the offending section, install a union and then take the new piece all the way to the firewall fitting. You'd need a tubing cutter which is the same one you can buy at Home Depot for copper plumbing line. You'll also need an aviation specific flaring tool. The flaring tool MUST be aviation specific because it makes the flare at a different angle than normal plumbing ones in order to fit aircraft AN hardware. Then bleed the brakes.

If that's not in your skillset, and A&P should be able to knock it out without too much fuss.

However you do it, you should get rid of those zip ties that are holding the line cinched up against the engine mount and replace them with adel clamps. Dirt and crud will get under those and act like sandpaper. Over time they've been known to wear grooves in the engine mount, which is obviously a big deal.

Also, if it were me I'd get rid of the foam inside the leg fairings. I don't like the idea of filling those up because who knows what sort of corrosion you could have going on underneath on the gear leg that you'd never be able to see or remediate. If you take the foam out, you can do a new brake line start to finish with no splices. If it's just expanding spray foam I think acetone will dissolve it.

edit- I just noticed in one of your pix that if you get rid of the foam, you'll have to add a tab on top of the fairing. Per plan, that faring is positioned and secured by a tab at the top that's held to the gear leg with a radiator hose clamp.

Terry. Thank you again. This is definitely in my wheelhouse. What size was the original aluminum line? Want to get the correct flaring tool and Adel clamps. Also, will see if I have the piano hinges in the fairings.

 

[JonJay]

I would strongly consider removing the foam. Foam can trap moisture and corrode the leg as mentioned by Desert Rat. It also makes it impossible to inspect the leg. I have seen this occur and, fortunately caught before the leg was unserviceable.
You may wish to look at better routing for the brake lines. It seems hap hazard with long lengths left unsupported. If you’re going to leave it that way switch to TS Flightlnes which would be much more tolerant.

 

[Desert Rat]

Terry. Thank you again. This is definitely in my wheelhouse. What size was the original aluminum line? Want to get the correct flaring tool and Adel clamps. Also, will see if I have the piano hinges in the fairings.

The part callout in the plans is for them to be fabricated from AT0-032X1/4 raw tube stock, which is what comes in the kit. You can order it in different lengths from vans for a few bucks. for the new run. Instead of zip ties I'd butterfly off the transverse engine mount tube with adel clamps, so you'd need 1/4" adels for the brake line and whatever size would go around the engine tube. I want to say that tube is 7/8" but it may be 3/4". I don't remember without looking.

I'd also get rid of that length of garden hose held on with pink wire ties on the starboard side. I get that they were trying to incorporate some chaff protection, but with the split oriented up there it's just asking for crud to get down in there and start working on the engine mount there. if youre new routing requires chafe protection there then clear tube with split oriented down and held on with mil-spec wire ties is a better solution. An even better solution would be a dollop of RTV between the engine mount and brake line to keep them from vibrating against each other. Same with where the heater scat tube is shoved through there.


If you haven't done it yet, go to Vans site and set up an account. In addition to buying stuff at their online store that gives you access to service letters and a full set of prints and parts lists for your specific plane.

If the gear leg farings are made to print, they will have a split seam down the trailing edge that's held together with a piano hinge inside. You get it apart by pulling the hing pin out from the bottom. The way it's supposed to work is that you pull the hinge pin out, loosen the radiator hose clamp at the top (which you obviously don't have), spread the faring apart and slide it fwd off the gear leg.

I don't have any pictures, but I'm confident somebody does. Maybe somebody reading this could post a picture or two showing the per print top clamp and how the piano hinge works on these farings?

 

[airguy]

Don - welcome to the RV family. It's a sickness that we fully embrace.

As aircraft repairs go, this is fairly benign and you have plenty of experienced people around in the California area with RV's, it should not be difficult to lure one of us out there with some pizza/beer bait and solve the problem.

l will agree with the posters earlier - if it turns out the gear leg fairings truly are foam filled, that should go away when you have time to address it.

 

[bjdecker]

Long story short, the right brake line that crosses under the engine was chafing on a clamp for the last 20 years - and it's now leaking. After looking things over, I think the best course of action is to cut out the damaged section (about 2 feet), plumb in a steel braid segment and adapt it to the remaining steel line. (See photos.) The main reason for this is the fact that I can't remove the gear leg fairings and they look to be foam-filled. (I bought the plane build in 2006 last year.)

Would love some feedback.

Welcome!

Ok, I know you didn't build this airplane - and I'm pretty confident that the guy who did build it (we know his work) did NOT use a piece of garden hose for anti-chafe. Along with that, the wrong nuts were used for the gear leg retention bolts, and there are other items that should be remediated before too much longer.

Reach out to your local EAA chapter, find a tech counselor and/or A&P-IA with RV experience. Then, with a copy of A.C. 43.13-B in hand, go through every system and fix everything that's dodgy.

 

[Desert Rat]

Hey Brian- Maybe I'm wrong, but in the 3rd picture that sure looks like a piece of green garden hose. I have no idea who built the airplane or who's worked on it since, so maybe I'm wrong. In any case, over time the engine compartment heat will likely cause those cheap zip ties to get brittle, unless harbor freight has started carrying a line of high temp zip ties in neon pink...

 

[bjdecker]

Hey Brian- Maybe I'm wrong, but in the 3rd picture that sure looks like a piece of green garden hose. I have no idea who built the airplane or who's worked on it since, so maybe I'm wrong. In any case, over time the engine compartment heat will likely cause those cheap zip ties to get brittle, unless harbor freight has started carrying a line of high temp zip ties in neon pink...

Nope - you aren't wrong...and zip ties vs powder coating on steel parts --> zip ties win, powder coat fails and exposes the steel to air...after that...

-- Break --
This reply is total thread drift, OT, and I apologize.

This thread is an example of one of the downsides of experimental aviation - and I suspect one of the reasons insurance underwriters are beginning to turn a jaundiced eye toward this market. Too many builders, maintainers, are taking shortcuts and using materials from the aviation aisle at Home Depot/Lowes.

Also, from another thread - just because an automotive part is available from Van's as part of its FWF kit, doesn't mean it's proper to use in an aviation application/context.

 

[donmtt]

Points all taken and I will do my best to clean up the mess. That said regarding the gear leg fairing…If there is no piano hinge on the fairings is my only option to pull the legs off? And is so, is that a big deal?

 

[mburch]

If there is no piano hinge on the fairings is my only option to pull the legs off?

If your gear leg fairings are truly glued in place, I'd just cut 'em off and make new ones. The parts are affordable and it's an easy job, certainly easier than pulling the wheels off. Some tips here.

 

[JonJay]

Nope - you aren't wrong...and zip ties vs powder coating on steel parts --> zip ties win, powder coat fails and exposes the steel to air...after that...

-- Break --
This reply is total thread drift, OT, and I apologize.

This thread is an example of one of the downsides of experimental aviation - and I suspect one of the reasons insurance underwriters are beginning to turn a jaundiced eye toward this market. Too many builders, maintainers, are taking shortcuts and using materials from the aviation aisle at Home Depot/Lowes.

Also, from another thread - just because an automotive part is available from Van's as part of its FWF kit, doesn't mean it's proper to use in an aviation application/context.

All good points but don’t think it’s limited to Experimental. My first airplane, certified, had a nice hunk of garden hose for the breather tube!
Insurance companies use actuaries to evaluate risk. It’s just a numbers game. If some of the poor workmanship or material choices end up causing accidents and claims, you most certainly are right.

 

[SwimmingDragon518]

I would strongly recommend giving Tom a call at TS Flightlines. He got me steel braided replacements in a couple days when I had a leak.

 

[donmtt]

I've got the leg fairings off and am starting to clean out the foam. There are piano hinges. Just took some digging to find the ends. My question is about the "tabs" you mention to hold the leg fairings. I do have a plan set that I bought, but I can't imagine what the tabs look like based on the drawings. It almost looks like you're supposed to cut out parts of the fiberglass and leave a "finger" behind to clamp? That seems destined to fail. Any chance you have a picture or other reference? (I looked at your post @mburch. I just don't think I have the tools and experience to build those fancy mounts. I do like them though...)

Those brakes lines aren't steel, they're just soft aluminum. When built, it comes in the kit as a roll and the builder cuts off a length, bends it by hand, and flares the ends. It would be pretty easy to cut out the offending section, install a union and then take the new piece all the way to the firewall fitting. You'd need a tubing cutter which is the same one you can buy at Home Depot for copper plumbing line. You'll also need an aviation specific flaring tool. The flaring tool MUST be aviation specific because it makes the flare at a different angle than normal plumbing ones in order to fit aircraft AN hardware. Then bleed the brakes.

If that's not in your skillset, and A&P should be able to knock it out without too much fuss.

However you do it, you should get rid of those zip ties that are holding the line cinched up against the engine mount and replace them with adel clamps. Dirt and crud will get under those and act like sandpaper. Over time they've been known to wear grooves in the engine mount, which is obviously a big deal.

Also, if it were me I'd get rid of the foam inside the leg fairings. I don't like the idea of filling those up because who knows what sort of corrosion you could have going on underneath on the gear leg that you'd never be able to see or remediate. If you take the foam out, you can do a new brake line start to finish with no splices. If it's just expanding spray foam I think acetone will dissolve it.

edit- I just noticed in one of your pix that if you get rid of the foam, you'll have to add a tab on top of the fairing. Per plan, that faring is positioned and secured by a tab at the top that's held to the gear leg with a radiator hose clamp.

 

[donmtt]

If your gear leg fairings are truly glued in place, I'd just cut 'em off and make new ones. The parts are affordable and it's an easy job, certainly easier than pulling the wheels off. Some tips here.

Thanks. I got the fairings off and am cleaning out the foam. I looked at the "tips" you referenced and I like the brackets for the top of the fairings. Trouble is, I just don't have the tools and experience to build the fancy units. Any alternatives?

 

[Desert Rat]

I've got the leg fairings off and am starting to clean out the foam. There are piano hinges. Just took some digging to find the ends. My question is about the "tabs" you mention to hold the leg fairings. I do have a plan set that I bought, but I can't imagine what the tabs look like based on the drawings. It almost looks like you're supposed to cut out parts of the fiberglass and leave a "finger" behind to clamp? That seems destined to fail. Any chance you have a picture or other reference? (I looked at your post @mburch. I just don't think I have the tools and experience to build those fancy mounts. I do like them though...)

I don't have a picture, but yeah, that's exactly what youre supposed to do. A finger on both the outboard and inboard top with a radiator hose clamp capturing them. Yes, there have been quite a few that have broken the tabs off, so people have come up with all sorts of clever alternate solutions.

That print is as confusing as heck because they've got it laid out flat to show you both sides at once and it doesn't took that way in real life. It doesn't help that they use that part as the starting point for more than one model so you've got a bunch of dimensions on it and you have to figure out which ones to follow for your plane.

 

[donmtt]

Thanks to all who commented. Placed my order with TSFlightlines this afternoon. Tom got back to me and they should be here soon. So that's settled. Now just gotta mount the leg fairings.