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Brake fluid leak

jwilbur

Well Known Member
Taxing the RV10 back to the hanger recently I realized I had no right brake. Pedal went down with no resistance. Thankfully I was close to the hanger.

After getting the airplane into the hangar I intended to remove the wheel pant but it was too hot to even touch.

I got the pant off today and based on the black all around the bleeder valve I assumed that had failed so I replaced it. As I began to pump fluid back in I realized the leak is somewhere else. Before I start taking everything apart, I figured I post a picture here and see what advice I might get.

You can see in the picture from where the fluid is gathering and dripping. Anyone care to venture a guess what I'll need to do/replace to fix this?

20190615_163105-e1560634451887.jpg
 
Check the connection on top of the caliper. If not, likely the O-ring around the piston is not sealing. Might be the pad wear was too much and uneven which could dislodge the piston. An easy fix. New brake pads and O-ring needed.
 
Make sure you find the cause, don?t just treat the symptom. The wheel pants should not be too hot to touch (the brakes, yes).
What is the white stuff around the threads?
 
White stuff is loctite 567 thread sealant. I'm assuming it was hot from the long taxi with me riding the brakes too much and maybe some burning fluid ????
 
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If the wheel pant was too hot to touch, you?ve got some other things to check. I had a similar experience when I had a stuck throttle and had to ride the brakes to slow taxi speed back to the hangar.

If things are getting that hot, there is a risk that some parts may warp. The key things to check are the rotor. That?s easy to check on a flat surface, the other thing are the two sets of bushings. If not torqued properly and they get hot, the ends will flare. This will cause the floating pad to hang and potentially the caliper too.

I didn?t check all the parts when I overheated the brakes that one time. Because of the additional friction that caused, the new pads pre-maturely failed. It?s been several years since that happened and they been fine since I replaced just about everything but the calipers.

My guess if you can?t see where the fluid is coming from that it?s most likely an o ring.

Because of the shipping delays from SLC to the east, I keep a set of parts to minimize downtime. I haven?t had to use them, but it?s good piece of mind.

I keep the next pad replacements, both sizes of bushings, o-rings, torx screws for the rotor attachment, and some or the nordlock washers.
 
Joe, does look like a caliper piston O ring failure from the pic. Like everyone has said, keeping spare parts is a fabulous idea---especially Orings and such that for minimal expense can sure mess up your week--especially if youhave to order them from the vendor.

Tom
 
Switch to synthetic rubber o rings (Viton). They can handle the heat better, however, if it was so hot you couldn?t touch the wheel pant, that is smoking hot and as others pointed out, everything will need to be inspected.
 
Hot wheel pant

One note of caution on the hot wheel pant. On my last condition inspection, after reassembling the wheel pants, I allowed the brake line to be in contact with the inside of the wheel pant. The result was blistered paint on the pant and an unwanted new project for me. Going forward I will be checking that I have no point of contact between the brake line and the wheel pants.

Why was the brake line so hot? The issue occurred while bedding in new pads.
 
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