Rudder Bar Lateral Play

[cessna170bdriver]

The picture below is where the copilot's right rudder arm connects to the right rudder bar. During the annaul inspection today, my AI noticed that there is about 1/4 to 3/8 lateral play of the rudder bar in the bearing. This does not appear to be from wear, but from the bearing being located about 1/4 to 3/8 to far to the right. The left rudder bar has less than half as much lateral play.

My AI is not overly concerned, but just thought it was odd, and was wondering if other 170's show this. I do have a 337 from about 1956 or '57 that shows a major repair that involved replacement of the landing gear bulkhead, belly skins, and cockpit floor. I was wondering if the floor rib to which the bearing is attached could have been misplaced slightly?

Miles

[n2582d]

Miles,
I have the opposite problem with my rudder shaft. I have an interference fit. The previous owner milled the aluminum bearings to correct this. Now I have bought new plastic bearings and am still trying to figure out the best solution for fixing the problem. It seems that when this area was rebuilt they should have installed the rudder pedal shafts and bearings before they drilled the rivet holes to install the front tunnel section and the rudder pedal outboard bulkheads (see fig. 19). If you are concerned about too much lateral play I would suggest getting new rudder shaft outboard bearings (one hole)--4 each of p/n S1674-1 and 4 each of p/n S1675-1, the inboard (two hole) bearings. These plastic ones are slightly wider than the original aluminum ones they replace. They were not that expensive.

[johneeb]

Gary, your pictures (which I plagerized here) are a great aid in following this sting.

It looks like you are on the right track to display pictures, try this, instead of putting the link to the picture storage site go the individual picture, right click on it, than go to properties, copy the individual pictures address, bring it to the 170 web site, and list it the way you did the picture storage site.

[n2582d]

Thanks for getting those pictures up John. I'll give your suggestions a try next time.

[cessna170bdriver]

Thanks Gary,

How much wider are the new bearings?

I checked cessnaparts.com and both part #'s are $1.66 each. They must be used in volume elsewhere to be that inexpensive!

Miles

[n2582d]

The new plastic blocks measured .778" wide. My old magnesium one that was not milled was .743" wide. So you would only gain .035" by installing new bearing blocks--hardly worth doing for reducing lateral play. Force each rudder pedal bar to the inboard end of its lateral travel and move the rudder pedal through its full range. If the arm which the spring and cable attach to don't contact the tunnel structure I would not worry about the lateral play. My magnesium blocks were seriously "wallered" (is that a word?) out. While checking your lateral play it would be worth moving the rudder pedal torque tube vertically and horizontally to see how much play you have in the bearing holes. You would probably get a more accurate feel for this with the springs removed--thereby removing the preload.

I saw that your bearing blocks were well greased. I wonder what Cessna is recommending as far as lubrication for the plastic blocks. Leaving them dry would help eliminate their collecting dirt.

While down in this area check for cracking of the aluminum structure where the inboard bearing blocks attach. This area is easy to inspect by looking through the inspection hole below the forward tunnel. Cessna issued SEB 98-3 to deal with this on the 172RG but I've heard of it being a problem on other high time single engine Cessnas as well. I'm considering mounting my inboard bearing blocks with AN970-3 large area washers to help spread the load.

[mongo2]

I've installed all new bearing blocks (plastic type). They fit in the original mtg holes . No Binding.
After installing return springs, when I force the left fwd tube to its inboard block, the left arm and spring are making contact with the tunnel.
Right arm doesnt seem to contact either way.
Of course I can force the tube the other way and it clears. I doesnt seem to matter much if I reverse which side the spring hole is entered.
It seems strange to have this much lateral play with new blocks. I'll have to check the springs again to make sure I have the ends correct.
Any other ideas?

Rick

[GAHorn]

.... I wonder what Cessna is recommending as far as lubrication for the plastic blocks. Leaving them dry would help eliminate their collecting dirt.

....

Powdered graphite.

[jrenwick]

Cessna's recommendations for all lubrication points are in the 100-series Service Manual (1962 and prior).

[mod cessna]

I have seen the plastic bearings broken. The small ones dont seam to break but the double ones do. Keep an eye on them. they are used on all the new Cessnas, that is why they are so cheap. I have also seen the cracked and broken bulkheads where they mount like n2582d described. The 170 will crack like this as well.
You could fix your problem by enlarging the holes and moving each bearing outboard.

[mongo2]

Thanks for the heads up on the double ones. I solved the problem by doing just exactly what you had said. I move the block slightly in order to keep the arm from rubbing the tunnel. Works well, and added larger washers below to prevent the cracking issue. Thanks again.

Rick

[n2582d]

I have seen the plastic bearings broken. The small ones dont seam to break but the double ones do. Keep an eye on them. they are used on all the new Cessnas, that is why they are so cheap.

Click to enlarge

.... I wonder what Cessna is recommending as far as lubrication for the plastic blocks. Leaving them dry would help eliminate their collecting dirt.

....

Powdered graphite.

The FAA gives conflicting advice to Cessna's in AC43-4A pg. 114

[minton]

While you are in there looking around, I have found several cracks in the area where the lefthand double bearing and the lower end of the righthand brake cylinder mounts to the aluminum "lefthand bulkhead Tunnel" p/n 0510113-3. Seems there are stresses applied in that area from using excessive braking pressures when applying pressure to the right hand brake pedal. Check it out.

[GAHorn]

....

.... I wonder what Cessna is recommending as far as lubrication for the plastic blocks. Leaving them dry would help eliminate their collecting dirt.

....

Powdered graphite.

The FAA gives conflicting advice to Cessna's in AC43-4A pg. 114

AC43-4A pg. 114.jpg

Yes, that's a conflict. Cessna also calls for graphite as aileron and flap hinge (piano type) lubrication. Since Cessna's manual is an approved document and the FAA's AC is not.....

[n2582d]

While you are in there looking around, I have found several cracks in the area where the lefthand double bearing and the lower end of the righthand brake cylinder mounts to the aluminum "lefthand bulkhead Tunnel" p/n 0510113-3. Seems there are stresses applied in that area from using excessive braking pressures when applying pressure to the right hand brake pedal. Check it out.

There are several SDR's on this as well. I've done a minor alteration by fabricating doublers with nutplates to reinforce the bulkheads that these rudder bar bearings attach to. On the left (pilot's) side the doublers also include nutplates for the bottom brake master cylinder attach brackets.

Click to Enlarge