Tailwheels

[scott]

First off I belong to several type groups on aircraft that I am involved with, and you guys as a group are the most informed focused group I participate in, Congrats to you.
Second I have a question on the best spring set up for the Scott tailwheel. I install a small safety cable in case of broken spring run down the center of each spring to each arm.
I wanted to know what the varied applications and preferences are out there for spring tension, Part#and Source included.
Some like immediate tight movement on the tailwheel some like a little lag or slop some like it so loose that it is allmost free castering.
I just wanted to get some feedback from the group.
Also Yall have mentioned some mechanical advantage alterations, I would like to hear more about that and the relative Ergonomics of each setup.

Thank you
and of course my name is scott but I used to have a maule T. W.

[Harold Holiman]

I used to have a Maule 8" tail wheel on my 170A. It is lighter than the Scott and I never had a shimmy problem with it. However I would definitely recommend the Scott for a 170. It is a much stronger design. I once had the stub axle break off on landing on my 170 and know of another person who had a Maule axle break the same way. For a 140 or other lighter plane the Maule tail wheel is fine but I don't think it is strong enough for the 170. Just my opinion.

Harold H

[N3243A]

Eric,

The bellcrank extensions are a do it yourself deal with a field approval required. There is no restriction in type of use, wheels, floats, skis. Mine is a strip of 0.125 chrome moly 1.125" wide by about 12" long. This is mounted underneath the rudder bellcrank and is stubbed off by 1/4" shims at each rudder cable attach point so that it doesn't interfere with the flange of the bellcrank. You will need to lengthen the bolts that attach the rudder cables to the bellcrank because of all the extra metal, shims and washers used that hold the thing together. Naturally, the tailwheel chains are moved from the little tabs on the bellcrank out to the ends of the extension resulting in much more leverage to the tailwheel arm.

There are several ways of doing this mod, but this is the way mine was done. Maybe JDH can outline how his was installed and approved? By the way JD, Scott must have changed back to steel on the regular 3214 arm as my new tailwheel arm will hold a magnet. Maybe your case inspired them to make some Quality Control changes!

Bruce

[knesbitt]

I have no opinion on the best tailwheel even though I have had pretty good luck with the Scott on my airplane. Someone mentioned trying a "birddog" tailwheel. If you decide to try that I have a name of a man that has a lot of "birddog" parts. Brown Aircraft Products, Robert Brown. (770) 693-3475. As far as Spruce is concerned I have always had good luck with them. They will match any price on anything I have found anywhere else and seem always willing to help.
Ken Nesbitt N3407D

[zero.one.victor]

Bruce,you raised some interesting points regarding steering geometry. I took a few measurements from my 170 today. The stock 3214 arm is 6-1/2" wide at the steering attach points. the 3214T is 6". So you're right,less tailwheel travel for any given amount of rudder deflection.
However,I noticed that my t/w steering attaches to the rudder bellcrank via a pair of small tabs riveted onto the bellcrank,inboard of the rudder cable attach points. These tabs are 5-1/2" apart at the steering attach point. The approved Scott 3200 installation drawing for the 170 shows the rudder cable attach bolts at the rudder bellcrank being replaced by AN42-6 eyebolts. These eyebolts,installed eye down,serve as the t/w steering attach points. The rudder cable bolts are 6-1/8" apart.
So if I re-rig my t/w steering as per the Scott drawing,I will gain back that 1/2" or so of mechanical leverage I lost when I installed the 3214T arm. Plus,the turned-up arms of the 3214T along with the turned-down eyebolts at the rudder bellcrank steering attach do add up to a little better pull angle on the t/w steering.
Granted,it's a small difference but every little bit helps. I'm probably gonna change over to the eyebolts,not much money or time involved,plus it'd then be as per approved data.

Eric

[zero.one.victor]

To the best of my knowledge,the BirdDog uses the same tailwheel as the 170. It may use the "3200-A" with turned-up arms instead of the 3200,but that's splitting hairs.
The BirdDog does use a heavier main leaf in the tailspring assembly.Some people have installed these on their 170's. I have mixed feelings on this. The BirdDog is a heavier airplane than the 170. Is the heavier tailspring gonna transfer more stress to the tailcone and t/w mounting bracket than the stock spring? Some people have brought up the same question with regards to fitting 180 gear to a 170. They may have a valid point in both cases.
Usually when a BirdDog spring is installed it is with the idea of preventing breakage. It might be a better idea to install a new stock 170 spring at regular intervals,say every 5 years? They are pretty notorious for breaking,after which the tailwheel assembly flails around still attached by the steering chains,beating the crap out of the bottom of the rudder.
That's why a LOT of the 170's you see have repair work visible in the lower rudder area.

Eric

[JDH]

You must remember that the Birdog has almost 100 more hosre on the nose; the rudder is effective quicker to help steer. I change my main spring at each annual; overkill, yes, but it has to be thouroughly inspected anyways and only costs $55, I clean, inspect and repack the bearings in the tail wheel at the same time. Much cheaper than any dammage it can cause if it breaks. As for the bellcrank extension, mine is 3/16" X 1" X 12" aluminum and I installed eyebolts, pointing down 5 1/2" from center to attach springs. As for the approval, I got the best AME/rigger in the area to install with me and rig the installation, tried in different snow, ice conditions, works good, looks good; good enough for me... I've been wondering: How many FAA inspectors are there, walking around the bush and peering into hangars and walking the flight line in the US?? I try to be extremely meticulous about the books on my airplane and to have all the STC's and all the rest of the approved installations, parts and components, but there comes a time that I have to become "Alaskan" (as in practical) and put good sense, practicality, function and performance/safety ahead of red tape... With the difference, that here, field approval are either informal: Your AME installs as per drawing or other official reference or you have to go the LSTA (limited STC) way, which is prohibitive. Don't tell anyone, I said this, but, if you are carefull to have any "alteration" look professional and made sure you are not "re-inventing" the wheel (use field proven design), or affecting the structural inntegrity and go about your business, no one will notice and no one will care. On the other hand, if your tie-down is next door to the FSDO or FAA agency and you brag about all your mods... Here, on a grass strip and where I fly to with my skis, no one snowshoes or skidoos to the plane to pick me up or inspect my plane or books... That said, we all have to decide how "kosher" we will be. Come spring time, the extension comes off, the penetrating tail ski comes off with it, the 3200-a goes back on, back to "kosher"... We have all noticed that it is extremely difficult to find a mechanic or anyone that knows these 50+ year old birds (isn't that one of the reasons we belong to this club?); how many inspectors do you think know the difference?? JD

[N1478D]

JD is VERY correct on the cost effectivness of avoiding the damage from a broken tailspring. Sometimes just the lower part of the rudder is damaged, other times the upper part of the rudder and the elevators are hit too. If a person changed the spring every other year or two, not saying that every year is a bad idea, it would only be about $30 for the insurance of avoiding the damage that runs in the hundreds of $'s.

[zero.one.victor]

JD,so your t/w steering attach points are a total of 11" apart? Wow,that must make it real effective. But you remove the bellcrank extension when you go back to standard wheel operations?

Eric

[JDH]

Eric, yes, you pretty much have to, unless you ALWAYS land on grass or gravel; on hard surface, my feet don't move that fast. JD

[wa4jr]

JDH...where do you get your Scott tailwheel mainsprings? I have an annual coming up and need to replace mine...as there is no entry in the logbooks of it ever being changed.

[doug8082a]

I got mine from A/C Spruce (pg. 183 p/n 06-15100 - $54.25). You can also get them from Univair (pg. 13 p/n U0542106 $51.52 according to my 2000 price list). Actually, the one from A/c Spruce has a Univair PMA sticker on it - go figure... they buy from Univair and resell it.

[JDH]

John, the last one I got was from Spruce and it is manufactured by Univair. Wag Aero also has it. If you wan the eyebolt kit while you are at it its Scott part number 3241-1A whichh is 2 of AN42-6 eye bolts (may want to get new: AN380-2-2 cotter pins; AN310-3 castle nuts; AN960-1- washers) JD

[n2902d]

My tailwheel steering is starting to go south. I noticed that the press-fit pin on the top of the tailwheel fork is pretty well worn down on the outer portion of the pin. This is causing the cutout on the lower copper washer beneath the steering arm to ride over the pin instead of grabbing it and turning the fork when commanding a turn on the ground. Has anyone been able to find a source for that pressed-in pin? The fork is in great shape otherwise; and I sure would hate to spend more than $150 for a new fork if I could just replace that itty bitty pin. I'm sure it's swedged in place, so I'm thinking a little heat on it could get it to pull out.

Thoughts and/or suggestions?
Thanks,
Mike

[powder_special]

I have a 51' 170A that I recently purchased. I have noticed that I am using quite a bit of brakes to steer. The tailwheel does not seem to be turning. Do I need to replace the whole assembly or should I be looking at individual worn parts. This is a scott 3200.
Thanks for the help!