My rudder has a lot more travel to the left

How to keep the Cessna 170 flying and airworthy.

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BrianW
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My rudder has a lot more travel to the left

Post by BrianW »

While doing some work on the tailwheel springs today, we noticed that the has a lot more travel to the left stop than the right. I assume this isn't normal, if anything I'd expect a bit more right rudder travel. The stop on the right is screwed all the way in, so there isn't any more adjustment before the belcrank hits it.

If this isn't normal, what should I inspect or have looked at? It's a significant difference in travel.
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brianm
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Re: My rudder has a lot more travel to the left

Post by brianm »

The first thing I would do is measure the rudder travel. It should be 16 degrees left and right. If you can't adjust the stops to get that, it's time to start checking the vertical stab and rudder assemblies for straight/square and damage.
Brian M
N2669V - '48
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GAHorn
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Re: My rudder has a lot more travel to the left

Post by GAHorn »

Brianm is correct. Here is a pic of the rigging instructions for the rudder. (Note that Item 3, cable tensions…are a wide range because there is no interconnect of the rudder cables. The only tension is provided by the rudder return springs below/near the firewall which pull the rudder pedals forward.)

Check the fairleads inside the aft sides of the tailcone (Item 27 in the depiction below) to make certain they are present and in good condition…and the condition of the cables where they pass thru those fairleads for fraying.

Notice also that the cables actually “cross” in the aft fuselage. (The right-rudder cable actually attaches to the pilot right rudder pedal…but the left rudder cable attahes to the co-pilots’ left rudder pedal.)
859DC54A-31BD-4FBC-926D-F0472C66E8CC.png
DDDF9374-99B4-48DD-B8D2-03709A0084CB.png
'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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BrianW
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Re: My rudder has a lot more travel to the left

Post by BrianW »

Thanks.. What manual did those drawings come out of? I'd like to get a copy of that manual.

To measure the rudder travel, is there a recommended tool, or will have I have to build something to accurately measure it? Will a prop protractor used on top of the vertical stabilizer do the job?
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BrianW
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Re: My rudder has a lot more travel to the left

Post by BrianW »

Went out and did some measuring of the rudder travel using a notepad, ruler and ipad app. Then I found the template Bruce made on here, so will go measure again with that as well. Travel seems to be well beyond 16 degrees, and there are no washers under the stops, so they are all the way in.

Whats the reason for not allowing more than 16 degrees? Guess more isn't better in this case?
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IA DPE
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Re: My rudder has a lot more travel to the left

Post by IA DPE »

My humble opinion is that the 170 has more than enough rudder. I said a while back that it’s the same rudder as a 190/ 195 with less H.P., but was corrected that it’s actually bigger as the 170 doesn’t have the tail “stinger” that those aircraft have.
1955 C170B N2993D s/n 26936
1986 DG-400 N9966C
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BrianW
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Re: My rudder has a lot more travel to the left

Post by BrianW »

I suspect rudder travel beyond 16 degrees may be less effective at providing yaw forces on the plane than setting it at 16,
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GAHorn
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Re: My rudder has a lot more travel to the left

Post by GAHorn »

Overtravel of flight control surfaces adversely affects Va, Maneuvering Speed. The airplane was designed for the stresses to be anticipated by full control surface movements…NOT MORE than that which is approved…and not Less either (for proper control, spin-recovery for example.)

In the case of rudder movement, the stops should also prevent contact between the rudder and the elevator at all combinations of movement of either.
'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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johneeb
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Re: My rudder has a lot more travel to the left

Post by johneeb »

And then there might be a limit to travel trying to prevent breaking off the vertical stab due to rudder doublet.
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hilltop170
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Re: My rudder has a lot more travel to the left

Post by hilltop170 »

BrianW wrote:
To measure the rudder travel, is there a recommended tool, or will have I have to build something to accurately measure it? Will a prop protractor used on top of the vertical stabilizer do the job?

Iphones have a built-in level/inclinometer in the Utilities app under “Measure”, “Level” that is accurate to 1°that can be used to measure elevator and aileron travel. Tap the screen to zero and it will give plus and minus readings.

The Compass can be used for rudder travel again accurate to 1°.
Richard Pulley
2014-2016 TIC170A Past President
1951 170A, N1715D, s/n 20158, O-300D
Owned from 1973 to 1984.
Bought again in 2006 after 22 years.
It's not for sale!
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