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What just happened !?

istrumit

Well Known Member
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
 
Stuck brake

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.
 
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.
 
Other mods

You can also look into this:

http://antisplataero.com/products/main-wheel-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.
 
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 :D).

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.
 
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 :D).
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.
 
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/community/showthread.php?t=114693

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

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
 
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.
 
I'd first look to see if you rolled the O ring in the brake caliper. Just replace it. I had one roll on me and it gave the indications you discribe.

Now look to see how bad you trashed the tire. I replaced the mains on an RV-10 after 30 hours of a new owner flying the plane. They were more square than round. The shimmy went away with the new mains.

Carl
 
Sticking master cylinders?

I have a 7, but the prevailing wisdom said that master cylinder return springs were needed - not optional. Another post said to check the pedal pivot for easy operation - no drag just a free pivot. I checked my 7 and installed a long bolt, as a pivot, in lieu of two single wobbly bolts. I through drilled and aligned the bores. The pedal got floppy loose, then the master cylinders were pressurized with 3 psi air and the spring return was tested. Even with a slow pedal release, it would completely uncover the fill port. I am holding on to the return springs as although it seems to be fixed, more might be needed with hours.

Point - check your installation and careful determine what the drag issue is, maybe it is a weak return spring in the cylinder, maybe it is drag in the pivot.In any case, eliminate the drag, then check the spring.

Good you got back to the hangar ok!!
 
I had a hard stop landing once and it acted pretty much as you describe. The caliper puck was cocked and locked and the O-ring was dripping. Rebuilt and all was good again. I NEVER had any shimmy from the mains, just occasionally from the nose wheel. I played with tire pressure and castor breakout force until I found a sweet spot. I would still occasionally get a shimmy but a little back pressure on the stick stopped it along with taxi speed.
 
I had a hard stop landing once and it acted pretty much as you describe. The caliper puck was cocked and locked and the O-ring was dripping. Rebuilt and all was good again. I NEVER had any shimmy from the mains, just occasionally from the nose wheel. I played with tire pressure and castor breakout force until I found a sweet spot. I would still occasionally get a shimmy but a little back pressure on the stick stopped it along with taxi speed.

I found on the RV-8A and RV-10 nose shimmy was generally an indication of a main tire out of balance or out of round. Once the nose tire is balanced and break out set, look to the mains if you have a new shimmy problem.

Carl
 
How commonly are -10 owners having to go with a single long pivot bolt for the brake pedals? Just installed mine yesterday with the AN3-7 and AN3-6 bolts, washers and castle nuts and all pedals seem free - the dry master cylinders return readily to the fully extended position.

I'm very familiar with the return spring issue from my 6A.
 
How commonly are -10 owners having to go with a single long pivot bolt for the brake pedals? Just installed mine yesterday with the AN3-7 and AN3-6 bolts, washers and castle nuts and all pedals seem free - the dry master cylinders return readily to the fully extended position.

I'm very familiar with the return spring issue from my 6A.

I built per plans and had no problem other than the need to add a heel spacer. A friend made one for me out of 1" diameter Delron on his milling machine.

Carl
 
I found on the RV-8A and RV-10 nose shimmy was generally an indication of a main tire out of balance or out of round. Once the nose tire is balanced and break out set, look to the mains if you have a new shimmy problem.

Carl

It was balanced but definitely out of round. If I had kept the plane it would have gotten the tire truing by Anti-Splat!
 
Scott-----I agree that you may have had a brake stick, as was mentioned above.

I agree it is entirely possible that it was as sticking brake, but if the side suspect of sticking is the same side that you were working on it would make a lot more sense to investigate whether you caused something, before running off to fix other problems that don't exist.
You mentioned that you broke a bolt... if it is the bolt I think you are talking about, it is AN4 which is not easy to brake. I am concerned that you are being a bit excessive when torquing, being that you appear to be new to working on airplanes. If that is the case, you could very possibly caused the problem your self........
 
BTYWI will be looking for something that I did wrong when I am out there tomorrow to take the fairing off.

TBH, its just some screws and one AN4 bolt...not much can go wrong.

Another user indicated that maybe that bolt was about to break and my breaking it was a good thing. I think that could be true, given that I have had a shudder on that side for a while and maybe that bolt was fatigued.

But, to your point, yes, always assume that if you have a problem in the area you were just working on, start with the idea that you screwed it up all by yourself ;-)

BTW..I bought the axle extender mod today....solve that bolt issue once and for all.
 
Another reference

Built per plans including aluminum brake lines and no issues.
An occasional nose wheel vibration on fast taxi speed,
easily avoided by slowing down a bit.
Only non stock part is the beefy aftermarket wheel pant extension.

Coming up on 450 hours on the second set of tires.
 
Master Cylinder Vent check.

Check to make sure your Brake Master cylinders are vented. Make sure its not capped off or has a block air vent. Don't ask me how I know this.....:eek:
 
I think its the brake pads.

I took that wheel pant off again and removed the caliber...

One of the pads was flaky and just starting to make metal.

Keeping in mind that this airplane sat without flying for nearly two years...it was in a dry climate and I had the engine scoped as part of the pre-buy...but, my guess is the brake pads are just dry/old/ruined....not to mention worn out.

So, I need a brake job.

Any pointers on how to ? Parts ? Etc.
 
I think its the brake pads.

I took that wheel pant off again and removed the caliber...

One of the pads was flaky and just starting to make metal.

So, I need a brake job.

Any pointers on how to ? Parts ? Etc.

The size brake pad used on the 10 is not very common -------Vans sells them at a reasonable price----I just order them from Vans.

Order two sets, and keep the spare in the plane so that if you ever need to do a repair when you are traveling, you have them---lots of FBOs do not stock that part.
 
Make sure you order the right pads for your caliper brand as the caliper brands shipped with the kits have changed over time and I don't think they are interchangeable across brands. For example, I have Grove brakes which use Grove 66-105 pads. You'll also need a rivet tool to set the rivets but I'm guessing there's probably a workaround (but I don't know for sure as I bought the tools).
 
You'll also need a rivet tool to set the rivets but I'm guessing there's probably a workaround (but I don't know for sure as I bought the tools).
I used a large drift punch under the manufactured head, and set the shop head with a dimple die. I think I used the dimple die for a #6 or #8 screw, I don't remember for sure. That got me 90% of the way there, the last 10% was a tap or two with another large diameter drift. Easy peasy.
 
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