Brake line attachment

I took the Rocket out today for some pattern work and lost the right brake. A inspection showed that the brake line was detached at the caliper. The line was a 3 inch extension off the standard plastic line with the end soldered into the caliper. I need to get it fixed and the easy solution is to resolder the fitting but it just does not seem like a acceptable practice. Is this setup used often in RV?s or a one off. The plan is to redo both brakes with conventional fittings at this point.
G

I've never heard of anyone soldering a line to a brake assembly. Aren't they all aluminum? Also, solder melts at...what...400F? Brakes get hotter than that. How about a photo of what you have?

I already left for home. I should have shot a couple of photos before leaving. I had a very long taxi and then a wait for some jumpers to land so I suspect the heat caused the failure.
G

yeah - seriously DON'T do that. Start over. Not just a heat issue, but also vibration fail mode with soldering there. Probably somebody not knowing what materials/ fittings to use with the NyLo... [which I personally is poor usage in this application - no flames please, do as you wish].

George,

"Detached" doesn't tell us about the nature of the failure, so it's kinda hard to bless or condemn the extension itself.

A metallic extension as you describe was probably an attempt to reduce temperature at the interface with the nylon tubing. In itself, that is not a crazy idea. Most nylaflow tubing grades are rated at a max operating temperature of 150 to 200F (melt is 365 to 500F). The 1000 psi pressure rating often quoted (by Aircraft Spruce, for example) is at 73F.

Returning to extensions, God is in the details...materials, fabrication, etc.

Side note; standard nitrile caliper o-rings fail if caliper temperature is pushed above 250 or so. The usual prophylactic is a switch to viton o-rings, good for a bit more than 400F. My point here is that if the fitting was de-soldered, the calipers need to be rebuilt, as the o-rings will have been toasted.

Now I branch into opinion. If as an auto dealer, I installed nylaflow plastic brake lines and compression fittings on your pickup truck, I'd be branded as a criminal idiot. I do not understand why builders continue to install them on fast aircraft. Personally I think you have a fine opportunity to install something suitable.

Thanks Dan, agree with everything you say. I leave the country today so it?s in the hands of a maintenance shop. Help has been offered from here to get some new braided lines made up. Going to see if I can work that out via phone.

DanH said:

Side note; standard nitrile caliper o-rings fail if caliper temperature is pushed above 250 or so. The usual prophylactic is a switch to viton o-rings, good for a bit more than 400F. My point here is that if the fitting was de-soldered, the calipers need to be rebuilt, as the o-rings will have been toasted.

Click to expand...

With that kind of extreme temperature event, I'd take a long, hard look at the linings too.

rightrudder said:

With that kind of extreme temperature event, I'd take a long, hard look at the linings too.

Click to expand...

Spoke to the mechanic. He does not think there was a heat event. The brakes were cool even with the long taxi when we pulled the fairings. It appears the solder just fractured. I think they are original to the build so they had about 800 hours. I had to go right up to NY for work so could not stick around. They seem to know RV?s and said they will have everything fixed when I get back Thursday. They are going to check into braided lines.
G

George---have them email you some pics that you could post here. It MIGHT help someone else.
Tom