What just happened !?

[istrumit]

I have been having a wheel vibration during a low speed taxi at a certain speed (RV-10). Not bad, but irritating. The recommendation has been to lower my tire pressure.

Last weekend I noticed my fairing on the pilot side had some play in it. Maybe 1/2 an inch. So I took it off, managed to tighten up the mounting plate (crows foot wrench, wo having to take the tire off). I also broke the bolt holding the extender to wheel, so I had to extract that and replace.

Anyway, long story short, it got it all back together and it was solid, so what to do ? Go flying of course.

It was a very cross windy day, so when I landed I did not get aligned and I landed pretty badly actually , in terms of alignment. I was crabbed to the right, so the left main was leading the right main.

As soon as I touched down, the whole plane started shuddering like an earthquake. I seriously considered I might break off a main.

I stomped the breaks and come to a full stop on the run way, shuddering the who time.

Then, I tried to taxi. But no luck. It was going to be a left turn, not matter how hard I stomped the right brake.

The fire truck came out to help me. I shut down and took a look. No flats, no fairing rubbing...nothing obviously wrong.

So I started up again, tried taxiing. Got the shudder for a second and could only turn left. Then it stopped and everything was normal again.

I have no idea what just happened. It seems like a stuck brake on the left side or something jammed between the brake pad and the rotor ?

Any ideas ? I am going to go take it all apart tomorrow, but I don't even know what to look for.

Scott

[douglassmt]

The brake cylinders will stick unless you install an aftermarket return spring. I have them on the pilot side and they've worked flawlessly for 1000 hours. I don't have them on the copilots side so on the rare occasion when I let someone touch them, I get a sticky brake and have to reach down and release it. It's happened maybe once. I can't recall where I got them but you can search the forums and find a source.

The shimmy/shudder is well known at around 30 kts. Some have installed stiffeners on the gear legs and report it fixed. I installed the stiffeners but still have it although it's not bad. You learn to brake a tad to slow quickly through it. However, your description of extreme shimmy may be something else, perhaps related to sticky brakes.

[snopercod]

Yes, the old-style (from 20 years ago) Matco master cylinders had a weak return spring which could cause the brakes to lock up. I went through a lot of tires before I figured that out and replaced the master cylinders. That said, you need to jack up that side of the plane and try to rotate the tire to see where the problem lies.

[douglassmt]

You can also look into this:

http://antisplataero.com/products/ma...el-bearing-mod

I haven't done it but I have other products from them and they are good. I also static balance my wheels/tires at annual and that seems to help.

I can't recall where I got my gear leg stiffeners but they are made out of wood (oak?) and easy to install. Still, I may take them off soon as they didn't seem to make a lot of difference.

[Auburntsts]

Originally Posted by douglassmt

The brake cylinders will stick unless you install an aftermarket return spring. I have them on the pilot side and they've worked flawlessly for 1000 hours.

Well I have only a tad under 150 hours so take this with a grain of salt, but I don't have return springs and have not had sticking issues (knocks on wood as he types ).

So you can compare apples to apples, I have stock MATCO cylinders, stock Grove calipers, MATCO parking brake, stock flex tubing from cylinders to the reservoir, stock rigid tubing from the parking brake to the thru fuselage fitting at the gear weldments, and Teflon lines from the fuse fitting to the calipers.

[BobTurner]

Originally Posted by Auburntsts

Well I have only a tad under 150 hours so take this with a grain of salt, but I don't have return springs and have not had sticking issues (knocks on wood as he types ).
ers.

I don't have any springs either. I believe the issue is the long bolt which is used as a hinge for the brake pedal. If the nut is too tight, or the holes not reamed or not well aligned, etc, there can be too much friction in the pivot and the pedal can hang up in the 'brake engaged' position.
You mentioned an 'extender'. Is this the stock hex shaped piece that goes outboard to the wheel fairing? Get rid of it. There are after market aluminum replacements available that are much thicker. The OEM piece flexes up and down, putting a lot of stress on the attach bolt. That bolt likely failed on removal due to being fatigued to near failure. You dodged a bullet there.

[Mike S]

Originally Posted by istrumit

Last weekend I noticed my fairing on the pilot side had some play in it. Maybe 1/2 an inch. So I took it off, managed to tighten up the mounting plate (crows foot wrench, wo having to take the tire off).

Scott

Scott-----I agree that you may have had a brake stick, as was mentioned above.

The return springs are a simple and easy addition to master cylinders.

As to the loose wheel pant--------you might want to take a look at this thread I posted a couple years back. I actually lost a pant during landing, due to the mount attach hardware coming loose. If you havent already done so, I highly recommend the spacer from PlaneAround.

http://www.vansairforce.com/communit...d.php?t=114693

Also, as Bob mentioned above, the stock extension piece can be a source of problems.

[bill v]

I had a shimmy after repacking the bearings and tightened the nut tighter then before and if you follow the plans when putting the brake petals in they tell you to put in washers between the petal and the frame but on yours the washers might have to be thinner then the drawing. the petals should not be tight in the frame but rotate on the bolt

[woxofswa]

Another possibility is that you flexed the tire enough that it caught up against a part of your pant, tore it, and folded the piece back up against the tire. I have seen that occur, and the solution is to widen the pant/tire gap all around. I had an incident early in my flyoff where upon landing it was like the nose wheel had a brake and the cabin filled with burnt rubber smell. I tried to clear the runway and the airplane struggled to move and then all of a sudden it cleared up and moved just fine. Taking a look at it at the hangar, a pebble had wedged itself between the center tread of the nose tire and the body of the nose wheel swivel. The pant had rubber bits everywhere inside. The tire only had about 5 landings on it but it now had a groove centered on it. The groove was shallower than the tread so I left it. I got over 300 hours on that grooved nose tire without a problem figuring that the groove would make a future stuck pebble less likely.

[Mike S]

More info on sticking brake issues, and a couple fix's


http://www.vansairforce.com/communit...ad.php?t=40235