Tailwheel steering arm play

How to keep the Cessna 170 flying and airworthy.

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JimNelson
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Joined: Sat Sep 14, 2013 10:07 pm

Tailwheel steering arm play

Post by JimNelson »

I searched the forum but couldn't find anything... how much fore and aft play should there be in the tailwheel steering arm? I move the rudder by hand and the steering arm moves about 10 to 15 degrees before it catches and the spring starts stretching. I know that some play is allowed, but how much is too much indicating something is off in the tailwheel internals?
1950 170A
N9955A s/n 19315
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GAHorn
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Re: Tailwheel steering arm play

Post by GAHorn »

JimNelson wrote:I searched the forum but couldn't find anything... how much fore and aft play should there be in the tailwheel steering arm? I move the rudder by hand and the steering arm moves about 10 to 15 degrees before it catches and the spring starts stretching. I know that some play is allowed, but how much is too much indicating something is off in the tailwheel internals?
It sounds as if your steering “pawl” is excessively worn. There should be zero “play” between the steering arm and the “detent” and you can test that with your hand.
'53 B-model N146YS SN:25713
50th Anniversary of Flight Model. Winner-Best Original 170B, 100th Anniversary of Flight Convention.
An originality nut (mostly) for the right reasons. ;)
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JimNelson
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Re: Tailwheel steering arm play

Post by JimNelson »

That makes a lot of sense. I can easily move the steering arm by hand quite a bit before it catches and moves the tailwheel. That may also be the cause of my "loose" rudder pedals mentioned in an earlier post. I was used to the feedback resistance from the tailwheel on the ground, and it now takes more travel to get things moving in the right direction. Time to get the local A&P to start taking things apart. Thanks!
1950 170A
N9955A s/n 19315
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GAHorn
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Re: Tailwheel steering arm play

Post by GAHorn »

Jim, you can do this yourself with common tools. The article being discussed in the other thread tells about the pawl replacement, but the exploded parts-diagram of the Scott tailwheel can lead you thru it. You will want a new “pawl” and new “Pawl spring”... which is a flat internal spring (bent at two places) which engages the pawl detents.
'53 B-model N146YS SN:25713
50th Anniversary of Flight Model. Winner-Best Original 170B, 100th Anniversary of Flight Convention.
An originality nut (mostly) for the right reasons. ;)
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JimNelson
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Joined: Sat Sep 14, 2013 10:07 pm

Re: Tailwheel steering arm play

Post by JimNelson »

The exploded parts diagram makes things really clear. And, there's a couple YouTube videos showing disassembly: https://www.youtube.com/watch?v=S-0i2MTe-A0 and assembly: https://www.youtube.com/watch?v=X1uAd0KSnCc which also helped. I'll see if I can work under the watchful eye of our local A&P and see what's up. And maybe learn which end of the wrench to hold since I am a lot better with software than hardware. I'll report back with what we find. Thanks for the help!
1950 170A
N9955A s/n 19315
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JimNelson
Posts: 31
Joined: Sat Sep 14, 2013 10:07 pm

Re: Tailwheel steering arm play

Post by JimNelson »

A followup. My A&P/IA took everything apart expecting to just clean, inspect, and regrease. What he found was the tailwheel bearing fell apart. The steering arm had just an inch of play but that pointed to a much larger problem. I'm glad that I didn't accept this play as normal.
Bearing.jpeg
Last edited by JimNelson on Fri Apr 09, 2021 3:30 pm, edited 1 time in total.
1950 170A
N9955A s/n 19315
User avatar
JimNelson
Posts: 31
Joined: Sat Sep 14, 2013 10:07 pm

Re: Tailwheel steering arm play

Post by JimNelson »

And another followup. After further cleaning, we found that the steering arm did indeed have a well-rounded detent. The pawl was very worn. As mentioned above, that was the cause of the steering arm play. Replacing arm, pawl, and bearing. While the bearing wasn't the cause of the steering arm play, without the pay I wouldn't have found out about the bearing.
1950 170A
N9955A s/n 19315
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GAHorn
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Re: Tailwheel steering arm play

Post by GAHorn »

JimNelson wrote:And another followup. After further cleaning, we found that the steering arm did indeed have a well-rounded detent. The pawl was very worn. As mentioned above, that was the cause of the steering arm play. Replacing arm, pawl, and bearing. While the bearing wasn't the cause of the steering arm play, without the pay I wouldn't have found out about the bearing.
Feels good when we accomplish these sort of things, heh? :P
'53 B-model N146YS SN:25713
50th Anniversary of Flight Model. Winner-Best Original 170B, 100th Anniversary of Flight Convention.
An originality nut (mostly) for the right reasons. ;)
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JimNelson
Posts: 31
Joined: Sat Sep 14, 2013 10:07 pm

Re: Tailwheel steering arm play

Post by JimNelson »

Feels great! The first small step to really knowing the aircraft. Thank you and the Association for this incredible learning resource.
1950 170A
N9955A s/n 19315
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