Main gear leg brake line

[konstantin_azarov]

Hi all,

I was gonna fly today and found brake fluid all around the axle fluid, so I assume the brake line inside the gear leg is leaking :/. I still have the old plastic lines in there, so I guess it's time to do the upgrade. I have trouble finding information about the replacement lines though. I thought there was an SB about it, but I can't seem to locate it.

Otherwise a couple of questions that I can't answer

• What kind of fitting is in the gear leg? I saw somewhere that it's 1/8 NPT?
• does anyone know if I can just order pre-made replacement stainless steel braided hose (from Aircraft Specialty say)? Or they won't fit through the top of the trunions? Or they are not flexible enough to accommodate gear motion?
• I saw a reference to kit P/N INS-741 somewhere that uses stainless steel tube and a custom machined mount at the top, is it still a thing?

If you could share how it's done on your airplane, it would help a lot.

Thanks!

[George Wehrung]

I would reach out to George Rosel when they get back from Oshkosh next week. And he lives pretty close to you just south of Denver.


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[George Rosel]

Konstantin,

Do not taxi/fly until your brake leak is fixed! You should also make sure your airplane is complied with service bulliten # SB037 (Gear leg witness hole).

I suggest you get with a build shop to direct your mechanic to replace all the nylaflow plastic brake lines with flexable steel lines. However, you will need to replace the lines going down each leg with stainless tubing. You can order this from McMaster-Carr part #8989k716. It is Smooth Bore Seamless 304 Stainless Steel Tubing, 3/16" OD, 0.028 Wall Thickness. You will need to order two 6' lenghts and cut them to size for each leg. Special cut off and flairing tools, etc. will be required along with numerous fittings. It is quite a process but well worth it as the nylaflow plastic lines just dont last all that long and will fail.

Hope this helps,

... George

[konstantin_azarov]

Thanks!

Definitely not going anywhere until this is fixed.

A couple of follow up questions:

• Why can't I replace the entire nylaflow run with a PTFE steel-braided line (like from aeroquip + reusable stainless fittings)? What's the point of the rigid stainless steel tubing?
• Do you have any pictures of how the stainless tubing is supported at the trunnion side? Is is just through an adel clamp on the flexible hose connected to the stainless fitting?

[Gordon Porter]

I used SS braided hose for brake lines on the ES I built. If memory serves me, those lines were supplied in the kit by Lancair. Circa 2007.

Aluminum tubing inside the fuselage to firewall, then nynaflow from there to master cylinders.

Gordon

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[George Rosel]

You will want to replace ALL the nylaflow lines, even the ones that connect to the master cylinders. See pictures of my plane before I replaced the lines down the legs with the small stainless tubing. See how you connect to the trunion, etc.

[konstantin_azarov]

Thanks everyone.

George, how did you connect your stainless steel tubing? I'm struggling to find AN819 sleeves and AN818 nuts for 3/16 OD tubing.

[George Rosel]

Konstatin,

Sorry for the delay getting back to you!!

The ends of the stainless steel tubing are connected with compression fittings.

You will need to order from McMaster Carr...

2 - 6' smooth bore seamless 304 stainless steel tubing 3/16" OD 0.028" wall thickness, PN 89895K716 ( these will be cut to length during install)
2 - Yor-Lock straight compression fittings, PN 5182K806 (these connect to the lower end of the new tubing inside each gear leg)
2 - Yor-Lock 90 deg compression fittings, PN 5182K819 (these connect to the upper end of the new tubing inside each gear leg)

From On Track Performance in Denver... (this is for all the material such as flex tubing and connections, etc. that you will need to make and replace the nylaflow plastic tubing)

Approx 20-23 ft of (-4) stainless steel braided teflon tubing, PN 600004
" 23 strait (-4) hose end fittings, PN FCM1101
4 - Unions, PN 481504-BL
2 - 90 deg adaptor fittings, PN 482204-BL
2 - 1/8 FPT coupler fittings, PN 491001-BL

Too much detail on how to install. Call me for a better explanation.

George
303-995-5501

[konstantin_azarov]

Thanks, appreciate it! No worries about the delay - I haven't been able to do much myself, the work's been crazy.

I think I understand how this comes together - I found a manual for an old aftermarket kit that did a similar thing. I also might solicit the help of Jeff from Jetstream Composites for this.

Good news is that I was able to take a better look at this (and pull the rear seat floor). And it appears that this might be a hydraulic leak, which just made it into the axle mount through the outside of the gear leg. Haven't found the source of the leak yet, will try to make some progress this weekend.

[konstantin_azarov]

Finally had some time to work on the plane. I'm pretty convinced now that this is not a brake problem and a leak in one of the hydraulic circuits made it to the axle mount along the gear leg. I cleaned everything up and I can't make it seep by pressing on the brakes.

I did buy all the parts and we'll replace them at the condition inspection in a couple of months. Thanks everyone and thanks George for instructions!

Now to figure out which fitting leaks...