Scott 3200 steering arm

How to keep the Cessna 170 flying and airworthy.

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Byocum
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Scott 3200 steering arm

Post by Byocum »

The Scott 3200 Tail wheel on the 1953 170 B I bought is in need of a rebuild. it currently has a straight steering arm on it. But the chains are tight against the springs enough where as they are slightly open. Im thinking if I go to the bent stearing arm the angle from the rudder arms to the bent stearing arm will shorten the distance by a small anount as the angle is decreased. On my 1946 140 removing or adding 1 Link on both sides is either to long or to short. It wpould be nice if they had some different length of the attachment Eyes. As per the installation instructions they should be without tension or slack when the Tail wheel is loaded with the weight of the airframe. Whats the preference on the stearing arms straight or bent. THX
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GAHorn
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Re: Scott 3200 steering arm

Post by GAHorn »

The difference is nothing as regards steering authority. But that difference is in the model tailwheel... 3200 or 3200A, the second being the "heavy duty" version.
The weight of the aircraft upon the tailwheel versus in the air should also make no difference when airborne (as regards steering chain tautness.) That's one reason springs exist to accommodate variations during taxy and when striking objects during taxy (not to mention that there should be no difference in the distance involved unless the leaf springs are damaged, as the distance does not change. Don't believe? Get a friend to lift the tail by the fuselage and take the measure.)

Bottom line IMO is it's cheaper to change/alter your steering chains. Some guys have been known to flatten links but also IMO it's better to have a bit of strain against the springs than to have loose chains. Another method is to use a different set of wire-loops/turnbuckles to attach them.
'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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Bruce Fenstermacher
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Re: Scott 3200 steering arm

Post by Bruce Fenstermacher »

The debate how to adjust the control chains on a Cessna 170 is one of the most hotly debated topics. Adjust tight or loose, How to make an actual adjustment in the length of chain and should it be done with the wheel in the air or on the ground and if on the ground at what weight. The arguments can go on for hours or pages and in fact have here if you look far enough.

In the end, you will have to decide how YOU want to adjust your chains.

First you should know that the Scott 3200 should be installed per Scott installation instruction I-68 according to the TCDS. But you will find very few 170s actually follow the instructions to a T. And BTW if you do as I once did, you'll find it works no better than what you might already have. I point this out because you won't find many who can stand on their high horse and tell you, your wrong cause their's isn't exactly how it should be done.

First you already figured out there is no adjustment for the chain. It is what it is. So lets discuss two methods I've employed to get a half link. The easiest is to take a pliers and while no one on a high horse is looking, gently, and slightly, squeeze the loop of about 10 links. This will stretch that loop and the length of the chain ever so slightly. I'm not talking about smashing them closed. No one should know the difference when your done. Do and many links as it takes. And before you ask, no your chain will not be weaker and stretch more if you do this and NO I don't have a bases of approval for this.

The second method is more obvious to me cause I know I-68 by heart. Thank goodness I don't own a high horse. Incorporating a AN115 shackle in the control assembly will incorporate about a link and a half of length to the control spring/chain/clip.
AN115-21.jpg
AN115-21.jpg (15.07 KiB) Viewed 13987 times
IMO the best place for this shackle is to attach it to the rudder control horn by placing the pin through the holes in the little tabs that are riveted on the horn. In fact this will stop the wear in those tabs. Then hook the spring to the shackle. Adjust as you see fit using the first method behind closed doors. There are so many 170s with a shackle incorporated in the control most think it should be there so there is little concern of unwanted scrutiny. It is AN hardware after all that most mechanics won't think twice about unlike the links you can find at ACE Aeromotive in the Hillman hardware section which you will also see on a half the tail draggers flying.


AN115 shackle: http://aircraftproducts.wicksaircraft.c ... e-shackles
Scott install instruction I-68: http://www.cessna170.org/forums/viewtop ... =40&t=8168
CAUTION - My forum posts may be worth what you paid for them!

Bruce Fenstermacher, Past President, TIC170A
Email: brucefenster at gmail.com
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GAHorn
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Re: Scott 3200 steering arm

Post by GAHorn »

Adding to Bruce's observation of the Scott "I-68" installation dwg:

Well... just for fun.... I don't see where the referenced dwg is identified as "I-68". (but clearly it's the same info) Nor does the TCDS state that is a basis for installation.

The TCDS references Scott Bulletin I-168... which I don't have a copy of. I do have a copy of I-168A


But I also wish to point out that I-168A does not conform to the Cessna Illustrated Parts Catalog IPC (not much surprise there.)
ScottBulletinI168.pdf
This version actually does identify itself IAW the TCDS...sort of...
(38.34 KiB) Downloaded 786 times
There's yet another Cessna illustration of this installation to the rudder bellcrank but I"m having a bran pharrt and can't find it.
TailwheelInstall.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. ;)
Byocum
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Re: Scott 3200 steering arm

Post by Byocum »

THX all. After searching and reading forum I found all of the tailwheelinfo i was looking for from previous post and threads. Great info for a new 170B Owner. Im amazed at how different it is from the 1946 140 rag wing I have. Its a preverbial KITE. My 140 loves wheel landings at 65-70 MPH and 1500 RPM. The 170B will oveshoot the whole runway if kept at 1500 RP. and flown like the 140!
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Bruce Fenstermacher
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Re: Scott 3200 steering arm

Post by Bruce Fenstermacher »

Woops I still haven't learned not to go from memory. It it Scott bulletin I-168. The Scott document linked before is a more recent copy of I-168 from Tyco/Scott. I've believe I've seen copies of I-168 more prominently marked than George posted

From the 170 TCDS:

204. Tail wheel assembly
(a) Scott Model 3-24B, steerable 5 lb. (+246) (+246) (+246)
*(b) Scott Model 3200, steerable, swiveling 8 lb. (+249) (+249) (+249)
(installed in accordance with Scott Bulletin I-168)
*(c) Maule SFS-1-2-P8 6 lb. (+246) (+246) (+246)

Those magic words I put in red, found in the TCDS are pretty important. That unapproved IPC on the other hand, how important is that. :D :twisted:
CAUTION - My forum posts may be worth what you paid for them!

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GAHorn
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Re: Scott 3200 steering arm

Post by GAHorn »

Like I said,..."not much surprise there."

On another note... notice that the judging rules also deduct for the Maule Tailwheel although it's mentioned in the TCDS. This likely is because both the Maule and the Scott 3200 are approved by their mfr's data...not Cessna. The TCDS may be misleading in that it is usually assumed that because it's on the TCDS it requires no further documentation. It has been argued not so ...that approval data is required from the mfr'r of the modification. (This is the argument made by the Javelin mod owner, namely that an approved copy or letter of approval is required from Javelin... or a field approval must be obtained. Notice the asterisk * in the TCDS notes which indicates the approval basis is not Cessna, but is instead the mod mfr'r.)

These things are so antiquated that the approval folks (FAA) seem to have little interest in the matter, as does most of us owners. But I'd be willing to bet that an energetic FAA Inspector could raise an ugly cloud if he saw a Geisse Safety Gear installed on a 170. If so, besides the 3200, this would mean the Sensenich prop and the Franklin Engine also needs STC paperwork. We're just lucky our old airplanes don't seem to raise many eyebrows regarding such matters. (As for the Franklin and the Scott 3200... notice the judging rules don't penalize although they are not "original" per the TCDS asterisk-notation...even tho' the Maule tailwheel can be installed under the same approval basis as the 3200.) :?
'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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Bruce Fenstermacher
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Re: Scott 3200 steering arm

Post by Bruce Fenstermacher »

For those following, one might get the impression our judges are all knowing Cessna 170 geeks walking around inspecting each 170 judged with a fine tooth comb for discrepancies to the IPC and TCDS. Surprise, they are not. Well sometimes I have pointed some things of interest out to my judging panel more in the vain of education rather than how something should be judged. There are so many 170s with baggage doors now days, we wouldn't want a 170 without one to be marked down. :wink:

The most important line in our entire judging rules is this:
  • 3. The judges' decision will be final. The score sheets will not be open for inspection. The whole operation is supposed to be fun and not taken seriously. If you don't win this year...maybe you will next year.
The part I underlined is key. No one knows how aircraft have been judged other than the judges. And it is suppose to be fun.

This is not to say the judges don't take judging seriously. I've never worked on a judging team with one who didn't.
CAUTION - My forum posts may be worth what you paid for them!

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Email: brucefenster at gmail.com
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c170b53
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Re: Scott 3200 steering arm

Post by c170b53 »

Seriously? Well just because I could be easily influenced the night before judging, I feel its unfair to single me out. Therefore I'm forever removing myself from judging due to my superior interlect. :D
Seriously I don't know what can be more of a hoot, judging aircraft or judging the spot landing!
Jim McIntosh..
1953 C170B S/N 25656
02 K1200RS
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