minton wrote: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.
Hi, I am new to the 170 association and fly a few aircraft and one is a Cessna 170.
I am contacting you on this post I found that dates back several years but maybe someone will chime in and help out.
The other day I was cleaning the area around the 170s brake/rudder assembly and notice the same Rudder Bar Lateral Play in the forward bar assembly. Looks identical to what is in the photo. Checked the bearings and they are plastic.
The aircraft is not mine but my cousins so I told him about it and he was concerned enough to ground his airplane until we find an answer. The spring arm is really close in the tunnel when the bar moves off center (the way I found it) so that is the main reason why we are asking if there maybe alternative to this Rudder Bar Lateral Play.
The A&P says to possibly take both bearing apart and evenly sand both inside areas where they mate when installed to bring both caps a bit tighter around the bar. We not sure about this one as it will need approval from an IA or possibly the FAA.
Anyway clad to be here and find some good information on the old 170 s
minton wrote: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.
P1010634.JPG
I did the same thing Gary. The only other thing I did was Mic the diameter of the clamps and the tubes. I then honed the clamps out, so that I had a better fit with respect to the tube. That is why the plastic parts keep breaking because of stress risers on the clamps around the tubes.
Sorry I might be misunderstanding you, you're saying that the tighter the more stress and the more chance that they will crack? I would of thought the looser fitting the more chances of movement within the bearing and then cracking. With pressure in foot pounds that we create without knowing it on the pedals and brakes is quite a bit.
I bought some wider washers for the top as one had suggested to place more equal coverage to the tops of the caps when installing.
It was suggested that a smooth clean bumper weld be made on the opposite side of the tube stop ring to keep the shaft centered and from moving side to side of the bearing housing.
Flaps Up wrote:Sorry I might be misunderstanding you, you're saying that the tighter the more stress and the more chance that they will crack? I would of thought the looser fitting the more chances of movement within the bearing and then cracking. With pressure in foot pounds that we create without knowing it on the pedals and brakes is quite a bit.
I bought some wider washers for the top as one had suggested to place more equal coverage to the tops of the caps when installing.
It was suggested that a smooth clean bumper weld be made on the opposite side of the tube stop ring to keep the shaft centered and from moving side to side of the bearing housing.
Thank you
Take the thing out and look at it as you assemble it. The stress riser is from bending the clamp when tightened. When I say get a Mic(micrometer) out, you are measuring .001's . In manufacturing some of these clamps have casting material still left on them and some are not even straight. You do not want the clamps loose, for the reasons you state.
Just an up date-seems we had some success today with the sanding of the rudder blocks to help tighten up around the rudder tubes to help aid in stopping the lateral play we are accounting. So far we have taken off on both the single mounts 1/32" (1mm) and has snugged up both when fully bolted down. We left a hairs amount of space so not to put to much pressure on the plastic when foot pounds are applied when braking. No binding and rotates on the shaft fine. We still need to do the double mounts.
We are looking for a box of parts that my cousin said he received when he bought the 170 several years ago and believes he saw the original rudder hard mounts in that box. If we can find it we will take a look and see the condition and hopefully reinstall if airworthy. Not to found of the plastic.
n2582d wrote:.... 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 wrote:Cessna's recommendations for all lubrication points are in the 100-series Service Manual (1962 and prior).
There is no mention of lubricating the rudder pedal bearing blocks in the '62 and prior Service Manual chapter 2 which covers lubrication. I found this is in paragraph 10-5:
My question however was about the new style plastic blocks. I found Cessna's recommendation for plastic (nylon) rudder bar bearing blocks in the 1977 C-172 Service Manual in paragraph 10-5:
As I saw what looks like grease on the failed part in the picture, I was wondering if petroleum distillates from grease might cause degradation and failure as shown in the entry on the last page. Here is a quote from this website:
Incompatible plastic-lubricant combinations often cause operating problems such as stress cracking or failure of the plastic component.
I think it is more likely the nylon rudder block failed because it is not adequately designed for the loads that are imposed on it. It would be nice if Cessna could come up with a service kit which included split bearings like connecting rod or crankshaft bearings that could be used with the original magnesium bearing blocks bored out.
I personally believe no lubrications should be used with the Nylon/Plastic, just from what I found while in that brake/rudder area cleaning was lost of dust and dirt, and if the lubrication attracts all that into the caps it will cut the bearing cap life in half.
If I can find the old parts that were removed (no luck yet) and find them usable I will be happy. When flying a tail wheeled aircraft we seem to always be on the rudder control system more that a nose wheel aircraft applying heavy amounts of force especially when on rough turf air strips, solid is good.
Thanks
Information please on the rudder pedal bars.
We were checking the co-pilots interconnected linkage that connects from the pilots side right pedal today. I noticed that when the co-pilots pedal is depressed that the inner (shinny shaft) shaft tube that the linkage is attached to for the brakes seems to hang or bind on that one side.
I removed the co-pilots right rudder pedal assembly and linkages and inserted a small screwdriver in the inner shaft were the 3/8 bolt hole is for the end linkage. When I rotate the shaft FWD and AFT I can feel a binding and it will also move a little more than 1/8" and not return to center on its own. The outer tube is for the rudders that I know and the inner shaft is for interconnecting the brakes. Can someone tell me if the inner shafts are a two piece shaft or one complete shaft? if I rotate from the right end were it binds the other end on the pilots side is stationary, no movement on that end of the shaft. I would think it would be a solid shaft from end to end. Also can the inner shaft(s) be removed for inspection? Are there bearings inside or just sleeve fitted in the outer shaft?
I am sorry I have no way of posting a picture.
Flaps Up wrote:Can someone tell me if the inner shafts are a two piece shaft or one complete shaft?
The inner shafts are one piece. I've never heard of these inner shafts breaking. If you look at Service Difficulty Reports (SDR's) for Cessna rudder bars you'll find numerous instances of the outer tube breaking/cracking at the rudder pedal attach stub. (None are on C-170's though -- 170 pilots have finesse; they dance lightly on their pedals. ) Cessna issued Service Bulletin SE 72-36 to solve this problem on 180/185 floatplanes and amphibs. The rudder bars p/n 0411306 and 0411306-1 are common to the C-170 and the early C-180's. This Service bulletin beefs up those rudder bars with p/n 0411306-208 and 0411306-207. Inspection of these rudder bars is the subject of Canadian AD CF-73-05.
Flaps Up wrote:Also can the inner shaft(s) be removed for inspection? Are there bearings inside or just sleeve fitted in the outer shaft?
See paragraph 10-4 of the Service Manual to remove the shaft. There are no other bearings inside, just the outer sleeves.
Flaps Up wrote:I am sorry I have no way of posting a picture.
I'd really encourage you and your cousin to join the Association. Not only would it benefit you in maintaining this 170 (under the supervision of your A&P) it would also help the rest of us see what you're dealing with. As a member you can post pictures and I'm sure I'm not the only one that would like to see a picture of a broken inner shaft.
Last edited by n2582d on Thu Dec 08, 2022 3:22 pm, edited 2 times in total.
Thanks Gary very good information. My cousin is an older guy who is one good pilot but is never interested in clubs or computers but let me work that.
At the most I fly the 170 about 20 hours a year when I am in town. I will pass this information on as I am heading out of town in a few days.
) Cessna issued Service Bulletin SE 72-36 to solve this problem on 180/185 floatplanes and amphibs. The rudder bars p/n 0411306 and 0411306-1 are common to the C-170 and the early C-180's. This Service bulletin beefs up those rudder bars with p/n 0411306-208 and 0411306-207. Inspection of these rudder bars is the subject of Canadian AD