Bent bell crank

[imncntrl]

This morning I noticed my bell crank was bent more than usual. It has been bent a little since I got the bird. I flew yesterday. This morning when I was doing my preflight, I noticed it was bent more than ever. Where the cable attaches to the left side of the bell crank is binding. The other side is fine. I have read info here about how the chains should have a little slack, these do not. I know originally, it must have been wind damage. I'm not sure if tight chains and some not so perfect landings are what is making it worse.

[Bruce Fenstermacher]

Jared,

The damage I see is from the bell crank hitting the stop. This is common wind damage caused by wing slamming the crank to the stop.

There are a couple of things I see that are not right in your pictures and I will list them. 1. The damage. 2. The eye bolt that the control chain is attached to should not be installed in the original control tab. The eye bolt should be long enough to replace the AN-3 bolt that holds the rudder cable to the bell crank. 3. Why on your second picture is the rudder cable loose. It should not be as it would normally be held tight by the rudder return spring.

Here is what I'd do if this was my airplane. I would immediately remove the eye bolts and attach the spring to the tabs directly unless the eye bolts are long enough to replace the AN-3 bolt as intended by the Scott installation instructions. If the eye bolt will work, move the eye bolts and reattach the spring if you want to use the eye bolts. To be honest I'm surprised the leverage created by the eye bolt as it is installed hasn't bent the tab.

Second I would clean up the bell crank so the rudder control cable attaching tabs smoothly slide over the damaged area as the rudder is moved. The picture shows the control cable slightly kinked and that is not the way it should naturally move. You don't want the damage scoring those control attachments. You might also install a thin washer top and bottom of both AN-3 bolts holding the control cable attachment tabs together, thus spacing them out a bit to clear the damage on the bell crank. Maybe the cable/attachments are kinked (in the picture) because the cable is slack. Figure out why the cable is slack. It should not be.

Last I'd effect a repair scheme to the bell crank restoring the stop. I might be able to take a picture of a scheme as I think one of my rudders has it on but I could at least draw a sketch of one. Of course you could replace the entire control tab. ($$$$)

[imncntrl]

Thanks for the info Bruce. I think the cable slack is just an illusion due to the bent bell crank forcing it up. One thing that I failed to mention is that it was bent much worse than this just minutes earlier. There was an older fella fueling up his plane next to me. I asked him his opinion of the damage. Before I could say anything, he jumped on the ground to look at it. Before I could say anything, he grabbed the rudder bell crank and tweaked it with all of his might. Not what I would have done. Anyways, I have a good IA/sheet metal guy checking it out later this week. I think I will order the spring kit and re-configure it per Scott's instructions as suggested. If used parts turn out cheaper..... I see a b model rudder for sale. I know the part number is slightly different for the rudder-bell crank and rudder. Am I correct in assuming they aren't interchangeable then?
Thank you,
Jared

[c170b53]

Well overall I'll says its goofed up and needs attention based and the condition of the hardware alone.
I would also have thought the cable was slack. There's no real cable tension other than the return springs as Bruce alluded to. Just guessing but it looks to me like maybe the eye- end is seized, or the attach bolt has insufficient grip length and is clamping the eye- end to the control horn. I'm hoping the chains are not taunt as well. There's tons of tailwheel info on this site.

[Bruce Fenstermacher]

Jared, you don't have to buy a new spring kit. You have the right springs and I'll bet at the end of the chains, (not in the picture) the right clips to the tail wheel. What is wrong is where those eye bolts are located that the springs are attached to. If you simply remove the eye bolts and attach the springs to the tabs directly, your set up will be the same as 98% of the rest of the 170s though technically not correct.
The eyebolts should replace the rear AN-3 bolts that hold the rudder control cable to the horn. So remove the eyebolts or relocate them IF they are long enough to provide correct grip length. If you need more chain links they are available at any good hardware store. It is regular sash chain. And quite often someone around the airport will have a few links.

As for the control horn bent or maybe twisted more than the pictures show. Hard to say how that might have happened. I'd think the improper placement of the eyebolts would have twisted the bell crank in the other direction than it seems to be. Wind damage us the usual suspect here. Is there evidence the rudder shin ever touched the edge of the elevator skins?

We recently discovered that contrary to popular belief all rudders models are not the same. The A and B model rudders are slightly different in the area of the control horn. I do not recall if the control horn itself is different between the models or whether an B horn could be used on a A. But I think it can because having an A myself I would have made a mental note that the B could not be used. So as you have an A model and I've confirmed you have an A model rudder in the pictures , look this over carefully before buying new parts.

I've just confirmed the actual control horn is the same A or B part number 0433113.

[bagarre]

Toss out the eye bolts and either hook the springs directly to the tab or add a shackle in there.

an115shackles.jpg

The L-19 BirdDog had an aluminum bumper riveted on right where your scrape marks are. It gave a much larger surface for the stop bolt to bump up against. I don't have a part number or a photo. George pointed them out to me a few years back when I was having similar rudder spring hook up issues.

There is a thread with a photo around here somewhere. It's getting really hard to find past information without a lot of creative searching. Its the curse of storing intel in a forum.

[gfeher]

I just added the shackles to my 52 B so I have the part numbers handy if you want to go that route. You'll need 2 each of AN115-21 cable shackles, AN393-11/MS20392-C11 clevis pins and AN380-2-2 cotter pins. The clevis pins are just slightly smaller than the holes in the rudder tabs, so they make a good bearing surface in the tab hole. They also make it very easy to remove and adjust the steering springs and chains. (The reason I added them.) I had to shave the outside edges of the shackle flats that hold the pin because the tab was too short and the pin would not go through the tab. But when I got them to fit there was plenty of meat remaining on the flats. (The tab will fail long before the shackle.) Bonus was that the shackles gave me better chain tension. It was a bit tight before I added the shackles but perfect after I added them. (I think I ended up using 19 chain links per side.)

Hope this helps.

[imncntrl]

I will look for some sash chain. Man, I like the looks of those shackles. Here's a picture of the tailwheel end of the chains.

[Bruce Fenstermacher]

Looking at the newest picture the clip on the right side at the bottom at the eyebolt on the tailwheel is a little pulled. You need to bend those ends in a little like the other side. Also there shouldn't be eyelets on the tail wheel control arm like you have.

The shackles are a great idea specially if you need them to adjust the chain length a half a link. You will find they are worth a chain link and a half and are a great way and about the only way I've found to get a half a chain link.

[GAHorn]

Just to be clear.... the tailwheel steering springs and chains DID NOT cause this damage.

It's much more likely that someone who was in the cockpit pushed aggressively on BOTH rudder pedals simultaneously...thereby pulling excessively on both rudder cables and bent that bellcrank.

The bellcrank is available as a new part from Univair, Spruce, and L-19 Inc (the latter can also supply the rudder-stops which contact the stop-bolts and protect the bellcrank.)
The advice to correctly assemble your system is good. The eyebolts are incorrectly installed. See the Scott installation diagram... or the C-170B IPC for the correct methods, ether of which will be fine.

[Bruce Fenstermacher]

Just to be clear.... the tailwheel steering springs and chains DID NOT cause this damage.

It's much more likely that someone who was in the cockpit pushed aggressively on BOTH rudder pedals simultaneously...thereby pulling excessively on both rudder cables and bent that bellcrank.

Normally the tailwheel steering springs would not cause a bend or twisting of the control horn, I agree. I could see someone standing on both rudder pedals and collapsing the control horn forward but not in the twisting direction this horn seems to have been bent. I think it just as likely something could have bounced up hitting the front of the horn bending it up in a twisting motion. That is the way it looks bent to me. Of course we didn't see it before it was "fixed".

We will likely never know what was the cause.

[gfeher]

The L-19 BirdDog had an aluminum bumper riveted on right where your scrape marks are. It gave a much larger surface for the stop bolt to bump up against. I don't have a part number or a photo. George pointed them out to me a few years back when I was having similar rudder spring hook up issues.

I'm doing the annual on my '52 B model and my IA noticed today that the bottom lip of the stop pad on the right side of my rudder bellcrank has been chewed up by the right stop bolt - kinda like Jared's but not as bad. I didn't notice it before as you really need to get under the right side of the tail to see it. The L-19 bumper seems like it might be a good fix. David or George, do you know if the holes of the L-19 bumper line up with the holes in the 170B bellcrank or does the L-19 bumper need to be modified in some way for use on the 170? Any insight you have would be appreciated.

Thanks in advance,
Gene

[imncntrl]

Due to the bad bell crank, my plane had an identity crisis for a few hours.

[GAHorn]

The L-19 BirdDog had an aluminum bumper riveted on right where your scrape marks are. It gave a much larger surface for the stop bolt to bump up against. I don't have a part number or a photo. George pointed them out to me a few years back when I was having similar rudder spring hook up issues.

I'm doing the annual on my '52 B model and my IA noticed today that the bottom lip of the stop pad on the right side of my rudder bellcrank has been chewed up by the right stop bolt - kinda like Jared's but not as bad. I didn't notice it before as you really need to get under the right side of the tail to see it. The L-19 bumper seems like it might be a good fix. David or George, do you know if the holes of the L-19 bumper line up with the holes in the 170B bellcrank or does the L-19 bumper need to be modified in some way for use on the 170? Any insight you have would be appreciated.

Thanks in advance,
Gene

If you have holes for a stop... then you likely have an L19 bellcrank and they'll maybe line up OK.
But if you're like most of us who added the stops later.... you'll have to drill new holes for the stops...and it won't matter.