Aluminum brake line service life

[kevinh]

Hi ya'll,

So I finished my RV in 2005 and made a note in my POH for "year 7, replace aluminum brake lines to wheel." Well - now I'm trying to figure out if I really should replace these lines in my next annual.

I suspect my note was was based in of a VAF discussion about 'flex line vs. solid soft AL with vibration loop' between the fuse and the wheels. And concern about vibration work hardening those lines leading to cracks. Dear wiser RV folks: How long have your aluminum lines lasted? Should I preventatively replace mine?

Making the lines originally was pretty easy so I don't mind making new ones. However, if there is no mechanical need I don't want to mess with something that is already working great.

Kevin

 

[Walt]

I like using 5052 for the brake lines due to the vibration at the caliper, if you fly a lot I would make the swap if nothing else just for the peace of mind.

Preventive maintenance is your friend

 

[Webb]

I had to replace both gear lines due to a crack near the top connector.

The first was an easy fix because there was enough slack to cut the line and put the connector on again. After the other side cracked, I went to the hydraulic shop and had 2 lines made (about 60 bucks) with teflon hose wrapped in stainless braid.

No more issues.

Having to do it all over again, I would have done it with the hoses from the start. The cost of the first repair was more than the hoses because it happened away from home which meant mechanic time.

If you replace, consider flexible lines

 

[Mel]

I used the original aluminum line (all the way to the caliper) included in the kit in 1989.
First flight May of 1993. Original lines still fine.

 

[flion]

I would suspect this is an IRAN item (IRAN = Inspect and Repair As Necessary).

 

[kevinh]

I used the original aluminum line (all the way to the caliper) included in the kit in 1989.
First flight May of 1993. Original lines still fine.

Good info - thanks. I think I'll keep my current lines and keep inspecting them.

 

[jbDC9]

Funny, I had the same thoughts last month when I needed new brake pads... I originally installed the standard hard lines and they've done fine with no leaks or problems for 5 years/835 hours, but they just looked like a failure waiting to happen. Even with a service loop at the caliper, when pulling the caliper off the slide pins to change the pads, the lines have to bend out of the way. I've already replaced the pads (and bent the lines) once... how many mores times until they fail? So I called Brett at Bonaco and got two gear leg flex lines for 58 bucks. Easy install and no more worries about the hard lines failing at the caliper.

 

[az_gila]

I used the original aluminum line (all the way to the caliper) included in the kit in 1989.
First flight May of 1993. Original lines still fine.

Mel, didn't the 89 kits specify (and provide) plastic line all the way down to the brakes?

 

[Mel]

Nope!

Mel, didn't the 89 kits specify (and provide) plastic line all the way down to the brakes?

My plans call for plastic lines from reservoir to master cylinders, from master cylinders to firewall, then aluminum from firewall to calipers.

 

[az_gila]

My plans call for plastic lines from reservoir to master cylinders, from master cylinders to firewall, then aluminum from firewall to calipers.

Yep... my mistake... I believe it was the RV-4 that originally specified plastic lines all the way to the calipers.

 

[vic syracuse]

Yes, they did (the RV-4's). I think I was in the first dozen to be completed, and we had the plastic brake lines. And, yes, I had a failure, and of course it was away from home. But luckily it was at the Dayton Airshow and the local EAA chapter helped to get it fixed. I haven't used plastic since.
On the first RV-10 I used the aluminum brake lines as per the plans, and eventually the line did break at the top of the gear leg. I replaced it with flex lines, and have used the flex lines on all subsequent airplanes. Does that mean the aluminum lines need to be replaced on all airplanes? I don't think so. I fly off of grass, so I know my gear legs are subject to a lot more vibration than pavement operations thereby creating a lot more flexing and potential work-hardening of the aluminum line, so my reason is pre-emptive.

Vic