Braking with full right rudder

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Braking with full right rudder

Postby brianm » Tue Jan 10, 2017 2:12 am

I get a fair amount of brake actuation when I put the right rudder to the floor. I've read the previous threads on this subject and I'm trying to narrow down the possible causes so I'm not wasting my mechanic's time when he comes out. What I've determined so far:

  1. Pressing the right rudder pedal causes actuates the master cylinder in the last 3/4" of travel.
  2. The left pedal is fine, although the parking brake bracket is hitting the firewall pad. I have the old serrated master cylinder pistons so if I understand correctly this isn't a problem (or at least not a risk of having a locked brake at an inopportune moment).
  3. Measuring from the firewall pad to the pedal hinge, I get about 6". The pad thickness is about 1/2".
  4. There doesn't seem to be any damage or excessive wear to the rudder pedal assembly, brackets, master cylinders, and so forth.
  5. The rudder itself appears to be mechanically sound.
  6. I didn't have the right tools to check the rudder travel accurately, but it seemed roughly equal side to side.
  7. Adjusting the clevis on the right master cylinder has little to no effect.
Sorry about all of the "abouts" in my measurements, this was an unexpected project so I didnt have a good tape measure or ruler with me.

My plan for the next trip to the hangar:
  1. Block the rudder to the center and verify that the pedals are even.
  2. Do an accurate check of the rudder deflection and adjust the limits if necessary.
  3. Shorten the turnbuckles until the pedal can go the the stops without actuating the brake.
(In other words, rig the rudder from scratch)

Any other ideas or anything else I should be looking at? With the pedals already set to the correct distance from the firewall, it seems like the most likely cause is either excessive rudder travel (easy to fix) or something is bent (not so easy). I'm a little worried that with the pedals already set a little more than the book distance to the firewall that shortening the turnbuckles further isn't a great idea. It's a long drive to the hangar for me and my mechanic, so any advice that might save us a trip would be appreciated.
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Re: Braking with full right rudder

Postby bagarre » Tue Jan 10, 2017 2:32 am

Pushing the rudder pedals shouldn't actuate the brakes at all.
This makes me think something is bent in the rudder bars / linkage bits.
It's not uncommon for things to be bent in there and there are lots of little linkages to be bent.
A good inspection of the rudder bars and linkage would be my first step. Maybe disconnect the passenger side brake links to see if the problem is still there (isolate the problem).

The serrated vs smooth brake rods are both susceptible to inadvertent lockage due to maladjustment.
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Re: Braking with full right rudder

Postby brianm » Thu Jan 12, 2017 4:33 am

As usual, it was something simple that I overlooked. The last time I was at the hangar it was 14 degrees out, so I didn't spend too much time crawling around. Today was a balmy 34 and the torpedo heater worked. Anyway, it turns out that the issue is the right side rudder stop adjustment, or rather the lack thereof. I marked up a little cardboard jig to measure rudder travel. Left travel is right on at 16 degrees. Right travel is off the scale, way over 20 degrees. The bell crank is also mushed up where it contacts the stop, and the stop itself clearly a (bad) homemade fix.

20170111_171947.jpg


Does anybody have any ideas how to get a wrench on the nut inside the bracket? I think I might have to grind down an open ended wrench. Need to talk to the mechanic and see if the bellcrank can be used as-is or needs to be replaced.
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Re: Braking with full right rudder

Postby gfeher » Thu Jan 12, 2017 3:16 pm

Brian, a broken rudder stop flange on the bellcrank is not unusual. Not the best design. If you have a B model and the rest of the bellcrank is fine, a relatively easy fix (compared to replacing the bellcrank), is to add L-19 stop pads/bumpers over the bellcrank flanges (including the broken one). (You may be able to do the same on the straight 170 and A models as well, but because I don't have either of them, I don't want to say.) See this thread, especially the pics on the second page showing the L-19 stop pads/bumpers added to George Horn's plane. viewtopic.php?f=24&t=5973&hilit=rudder+bellcrank

You can get the stop pads/bumpers from Air Repair, Inc. http://www.airrepairinc.com/ 662-846-0228. They're good folks. Tell them you are a TIC170A member.

I did this fix to my plane at my last annual. Do both sides at the same time. Also, if the holes of your tailwheel spring tabs are elongated, you might as well change them at the same as the L-19 pads use the same rivet holes. At least for the B model, the L-19 spring tabs are the same as B model tabs, so you can order them from Air Repair at the same time. Here are the notes I made for myself from the same repair I did last year:

"6/2016 Rudder Bellcrank Stop Repair (Adding L-19 Bumpers and New Tailwheel Spring Tabs)
Bumper: L-19 p/n 0660341 Tailwheel Steering Tabs: L-19 p/n 0660071, C-170B p/n 0433132
Remove rudder before making the repair. The time saved by removing the rudder will far exceed the time it takes to remove and reinstall the rudder. The rivet holes are no. 30 drill size for no. 4 rivets. The holes of the bumper and new tabs match the holes of the for the original spring tabs on the bellcrank. However, it may take some adjustment of the forward edge of the bellcrank (at the area of the rudder stop) to get the bumper to align with the holes in the bellcrank. After taking the rudder cable off the bellcrank, slip the bumper on to the bellcrank with the offset rear hole oriented towards the outside and cleco the rear hole. Then try pivoting the bumper inward (toward the fuselage) to see if you can get the forward hole to line up. It’s likely that you won’t and will need to do the following: bend the vertical flanges on the bellcrank more vertical so they fit in the bumper (behind its front face), and/or file or shave off a slight notch on the forward edge of the bellcrank at the inward edge of the bumper so the bumper can pivot inward enough so its forward hole lines up with the forward hole on the bellcrank. (A Dremel works well make the notch -- remember to dress the notch with a round file to eliminate stress risers.) When both holes line up, it’s likely that the bumper will not fully line up with the rudder stop bolt on the fuselage, but contact it near its outer edge. That’s just the way it is. The holes on the bumper/tab/bellcrank are too close together to use clecos to hold the bumper and tab during riveting. You cannot even use a cleco in one of the holes while riveting the other because it interferes with both the rivet set and bucking bar. The bumper is made of steel and is “springy,” so you must use something to clamp it during riveting. Before riveting, buy a 1’ long flush head machine screw thin enough to fit in the rivet hole, along with a nut, and use it to clamp the parts together to rivet the other hole. (You need a flush head screw so the head does not interfere with forming the shop head on the rivet in the other hole.)"

These notes were specific to my plane, but I'm sure that there's enough in them to be useful to you. Once installed, I think the L-19 bumpers are far more durable than the stock bellcrank flanges.

I hope this helps.
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Re: Braking with full right rudder

Postby brianm » Thu Jan 12, 2017 4:01 pm

That might work. I have a '48, but as far as I can tell the '48, A, and B all use PN 0433113 for the bell crank.

At this point I think I've done all I can on my own and it's time to get an A&P on it. It needs at least one new rivet anyway. The bolt on the right stop was run in so far that it took the head off of the rivet inside the bracket. It fell off once I had the bolt backed out a couple of turns.
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Re: Braking with full right rudder

Postby n2582d » Mon Mar 18, 2019 5:04 pm

gfeher wrote:Brian, a broken rudder stop flange on the bellcrank is not unusual. Not the best design. If you have a B model and the rest of the bellcrank is fine, a relatively easy fix (compared to replacing the bellcrank), is to add L-19 stop pads/bumpers over the bellcrank flanges (including the broken one). (You may be able to do the same on the straight 170 and A models as well, but because I don't have either of them, I don't want to say.) See this thread, especially the pics on the second page showing the L-19 stop pads/bumpers added to George Horn's plane. http://www.cessna170.org/forums/viewtop ... +bellcrank

You can get the stop pads/bumpers from Air Repair, Inc. http://www.airrepairinc.com/ 662-846-0228. They're good folks. Tell them you are a TIC170A member.

I did this fix to my plane at my last annual. Do both sides at the same time. Also, if the holes of your tailwheel spring tabs are elongated, you might as well change them at the same as the L-19 pads use the same rivet holes. At least for the B model, the L-19 spring tabs are the same as B model tabs, so you can order them from Air Repair at the same time. Here are the notes I made for myself from the same repair I did last year:

"6/2016 Rudder Bellcrank Stop Repair (Adding L-19 Bumpers and New Tailwheel Spring Tabs)
Bumper: L-19 p/n 0660341 Tailwheel Steering Tabs: L-19 p/n 0660071, C-170B p/n 0433132
Remove rudder before making the repair. The time saved by removing the rudder will far exceed the time it takes to remove and reinstall the rudder. The rivet holes are no. 30 drill size for no. 4 rivets. The holes of the bumper and new tabs match the holes of the for the original spring tabs on the bellcrank. However, it may take some adjustment of the forward edge of the bellcrank (at the area of the rudder stop) to get the bumper to align with the holes in the bellcrank. After taking the rudder cable off the bellcrank, slip the bumper on to the bellcrank with the offset rear hole oriented towards the outside and cleco the rear hole. Then try pivoting the bumper inward (toward the fuselage) to see if you can get the forward hole to line up. It’s likely that you won’t and will need to do the following: bend the vertical flanges on the bellcrank more vertical so they fit in the bumper (behind its front face), and/or file or shave off a slight notch on the forward edge of the bellcrank at the inward edge of the bumper so the bumper can pivot inward enough so its forward hole lines up with the forward hole on the bellcrank. (A Dremel works well make the notch -- remember to dress the notch with a round file to eliminate stress risers.) When both holes line up, it’s likely that the bumper will not fully line up with the rudder stop bolt on the fuselage, but contact it near its outer edge. That’s just the way it is. The holes on the bumper/tab/bellcrank are too close together to use clecos to hold the bumper and tab during riveting. You cannot even use a cleco in one of the holes while riveting the other because it interferes with both the rivet set and bucking bar. The bumper is made of steel and is “springy,” so you must use something to clamp it during riveting. Before riveting, buy a 1’ long flush head machine screw thin enough to fit in the rivet hole, along with a nut, and use it to clamp the parts together to rivet the other hole. (You need a flush head screw so the head does not interfere with forming the shop head on the rivet in the other hole.)"

These notes were specific to my plane, but I'm sure that there's enough in them to be useful to you. Once installed, I think the L-19 bumpers are far more durable than the stock bellcrank flanges.

I hope this helps.
Great step-by-step instructions for installing the bumpers Gene. Now if you really want this to last forever follow Cessna’s instructions for installing the bumpers on the C-150/152 in SEL 27-02. Apparently there has been a problem with dissimilar metal corrosion after these bumpers were mounted in accordance with Service Kits SK152-24B or SK152-25B.
DC781CB6-8197-47B6-BC30-4825EEE51AFF.jpeg
C-152 Rudder Stop Bumper
Because corrosion of the rudder horn could cause “loss of aircraft control” they pull out all the stops to prevent corrosion from happening. After applying alodine to the horn the horn and bumpers are epoxy primed and polyurethane painted. Next the parts are assembled with a sealant using anodized rivets (MS20470AD4-7A). Finally, the assembly is coated with Cor Ban 23, a corrosion inhibiting compound coating.
Last edited by n2582d on Tue Mar 19, 2019 12:27 pm, edited 2 times in total.
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Re: Braking with full right rudder

Postby gfeher » Mon Mar 18, 2019 7:45 pm

Interesting Gary. I may be mistaken, but if I remember correctly, both the L-19 "bumpers" and the C-170 rudder horn are made of the same material -- aluminum. So I'm not sure that there would be the same dissimilar metal corrosion issue. What are the C-150/152 bumpers and horns made of? I didn't see it in SEL 27-02. Edit: I should have read my original post from 2017 above (where I say the bumper is made of steel) before responding here from memory. So disregard my previous sentences. I was mistaken and Gary may have a point. It's probably worth carefully reading SEL 27-02. I wonder if any of the L-19 folks have noticed any corrosion issues with the bumpers.
Last edited by gfeher on Mon Mar 18, 2019 9:57 pm, edited 1 time in total.
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Re: Braking with full right rudder

Postby Bruce Fenstermacher » Mon Mar 18, 2019 8:49 pm

Your guys notice over two years have passed since Gene wrong that post? Doesn't matter, good material.

bagarre wrote:Pushing the rudder pedals shouldn't actuate the brakes at all.
The serrated vs smooth brake rods are both susceptible to inadvertent lockage due to maladjustment.


In my opinion, this statement is not correct. As a current owner and operator of a set of master cylinders with serrated rods, I've studied this carefully. The parking brake activation lever is totally different than the later smooth style. It can not hit the firewall and be inadvertently applied. This is the good news about the serrated rods. The bad news is there is a early SN to remove the serrated rods from service. As I recall the reason being the rod had been known to snap at a serration.
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Re: Braking with full right rudder

Postby ghostflyer » Tue Mar 19, 2019 12:43 am

As I am trying to get my head around the different types of braking systems and having looked in the parts catalogue and inspecting my system also and replacing the brake cable , I know I have a the smooth shalf actuators ,but apply the park brakes is by pushing both pedals down and pulling handle under the instrument panel which has a ratchet for locking which pulls on a split cable system to depress the pedals . My Cessna is 170A. So my question is this a modified braking system or original for that series?

It’s nearly the same as the Cessna 180,s we had in the Army.
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Re: Braking with full right rudder

Postby n2582d » Tue Mar 19, 2019 5:00 am

Back in 2008 you described your parking brake system as follows:
ghostflyer wrote:... Our 170A [serial no 19006] has a different brake system so far discussed. Our system is similar to Page 44 fig 25 L/h bubble inset of the Cesna parts manual. A cable attaches to the top of each brake piston/rudder pedal attach point and then routes around a pulley and joins mechanically to a single cable which then joins to a ratching T handle . The handle must be pulled and brake pedals depressed for park brake to be deployed. ... .
It sounds to me like you have the cane handle system which Cessna first installed in C-172's in 1963. Does it look anything like this?
Hand Brake.jpg
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Re: Braking with full right rudder

Postby ghostflyer » Tue Mar 19, 2019 8:06 am

Yes very similar to early Cessna, I am trying to work out the legality of my system. Our governing body now requires every 3 years a confirmation registration check and a mod and STC check ,SB,EO and or a Fligh manual supplement . Plus does it affect W and B . I have many STC,s and Eo,s so trying to work out a legal way to make this legit. Also have a half of float plane kit fitted on the LH side ,so that’s going to be a interesting write up.
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Re: Braking with full right rudder

Postby wingnut » Wed Mar 20, 2019 4:48 pm

Bruce Fenstermacher wrote:Your guys notice over two years have passed since Gene wrong that post? Doesn't matter, good material.

bagarre wrote:Pushing the rudder pedals shouldn't actuate the brakes at all.
The serrated vs smooth brake rods are both susceptible to inadvertent lockage due to maladjustment.


In my opinion, this statement is not correct. As a current owner and operator of a set of master cylinders with serrated rods, I've studied this carefully. The parking brake activation lever is totally different than the later smooth style. It can not hit the firewall and be inadvertently applied. This is the good news about the serrated rods. The bad news is there is a early SN to remove the serrated rods from service. As I recall the reason being the rod had been known to snap at a serration.

Bruce,
Seems you and I had a phone conversation about this years ago. I think it was you. I had a full set of rudder pedals, linkages, torque tubes, and brake cylinders all assembled yet not installed in the plane. I noted that the geometry of the rudder pedals/linkages, and master cylinders, could cause brake actuation in certain circumstances. I think the major factor was the distance from rudder pedal to firewall, and how the open loop design of the rudder cable system can be adjusted for the correct distance from firewall (7 inches sticks in my head). Contributing factors included worn pedal linkages and torque tube bushing, which cumulatively change the geometry.
I believe I sent you a video to illustrate what was happening, and that you subsequently posted about the issue here (not the video, just a good description). I have slept since then, so I may be thinking of something entirely off base. I'm not good at using the search feature, but I think it would have been year 2010, give or take.
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Re: Braking with full right rudder

Postby gfeher » Wed Mar 20, 2019 7:29 pm

Hey Del, did you see Gary's post above about SEL 27-02 and dissimilar metal corrosion between the bumpers and rudder horn of C150/152's? Did you ever run across dissimilar metal corrosion between the bumpers and rudder horn on any L-19's? Just wondering if this is a big issue for those of us who have installed the L-19 bumpers on our 170's.
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Re: Braking with full right rudder

Postby Bruce Fenstermacher » Wed Mar 20, 2019 11:17 pm

Yes Del, we did have that conversation. and I did write about it cause my brake was (and still slightly does) engage. I adjusted the pedals aft to correct most of it as I recall.
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Re: Braking with full right rudder

Postby pkissel » Sat Jan 15, 2022 2:02 am

Hi guys

I have a similar brake actuating when I apply full right rudder - almost ground looped me and scared the S out of me when full left rudder didn't stop the plane from going right! Off and into the grass I went.

So for a short term fix I added a longer screw and washers to the rudder stop screw ( sorry I don't know the proper names) after we had noticed the rudder horn peeling back and being worn - causing too much travel when I applied right rudder. If I was "soft" with right rudder it was fine but if I push a bit harder it gets "mushy" and gives me more travel thus causing the master cylinder and brake to actuate. The longer screws stopped the amount of travel and stopped the mushy feel thus stopping the brake being applied when applying full right rudder.

I have since had my mechanic order the reinforcement brackets for the rudder horn and install those. I then put the original rudder stop screw back in....taxied around and it STILL grabs right brake!
SO I plan to put the longer screw and washers back in tomorrow. Taxi and see what happens.


Do you think this could be something bent in my rudder pedal linkage?
or My rudder degree of travel on each side being off - mechanic said he got 16 degrees on right side and maybe a touch less on left side.
IF the longer screw/stop fixes the issue is that acceptable or should I be tearing into all of the linkage?

Left rudder and brake is fine.

Thanks for any advice and help!
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