Since many of you probably have a Scott tailwheel, I'm looking for some help from owners familiar with adjusting the Scott tailwheel.
I recently removed and replaced many old and worn parts in my tailwheel including the spring and pawl.
I am having difficulty adjusting my newly rebuilt tailwheel to break and swivel with the correct amount of side pressure. I understand the need for the wheel not breaking prematurely. Mine breaks when the aircraft is turning left with a moderate amount of pressure (which seems correct), and will not break when the aircraft turns right at all. I can push the tail of the aircraft in that direction with my hip against the tail in front of the horizontal stabilizer until the tailwheel skids sideways across dry pavement, and still the wheel will not break and swivel. I have removed and reassembled a few times in an attempt to find the problem, to no avail. Any suggestions ?
Scott 3200 tailwheel problem
Moderators: GAHorn, Karl Towle, Bruce Fenstermacher
Re: Scott 3200 tailwheel problem
Despite your description, it certainly points to a Pawl/Spring problem. That spring engages within depressions that should be compared to each other, left-right. That's where I'd start.
'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.
50th Anniversary of Flight Model. Winner-Best Original 170B, 100th Anniversary of Flight Convention.
An originality nut (mostly) for the right reasons.
Re: Scott 3200 tailwheel problem
Since this website is for the education of all, I feel it my duty to reveal my findings on the Scott 3200 tailwheel issue. 
I was entering the grounds of the airport on the way to waste some time in my hanger when jrenwick (of this site fame) passed me and immediately wheeled around to have a chat with me. He had read my post. In the past, I have gained much knowledge from John on many C170 subjects. As usual, John was helpful and resolved the problem in short order.
I had been advised by a friend to change from tension springs to compression springs on my tailwheel to get better steering. (Please withhold ridicule and laughter until the end of the story.
) In fact, I did get better steering with the compression springs, but since the spring change was made at the same time as the tailwheel rebuild, it masked the improvement in steering corrected by the rebuild, but caused the castoring problem at the same time.
By standing behind the tailfeathers of my C170 as I tried to cause the wheel to castor, John was able to see that the compression spring on the affected side "bottomed out" before the steering arm released the wheel to castor. Then, by unhooking the chains on both sides (as John suggested), I was able to get the wheel to castor perfectly in both directions with just the right amount of pressure on the tail of the aircraft. As you might imagine I am ordering new tension springs for the tailwheel. John also discussed with me earlier posts discussing compression springs and their disadvantages. Thanks to John and George for the responses to my original post. OK, now you can laugh.
Hopefully this will refresh the issue with those who have seen it before and teach the lesson of changing too many things at once. I'm so happy to have my tailwheel working correctly again.
N170GA
Thanks to all.
I was entering the grounds of the airport on the way to waste some time in my hanger when jrenwick (of this site fame) passed me and immediately wheeled around to have a chat with me. He had read my post. In the past, I have gained much knowledge from John on many C170 subjects. As usual, John was helpful and resolved the problem in short order.I had been advised by a friend to change from tension springs to compression springs on my tailwheel to get better steering. (Please withhold ridicule and laughter until the end of the story.
) In fact, I did get better steering with the compression springs, but since the spring change was made at the same time as the tailwheel rebuild, it masked the improvement in steering corrected by the rebuild, but caused the castoring problem at the same time. By standing behind the tailfeathers of my C170 as I tried to cause the wheel to castor, John was able to see that the compression spring on the affected side "bottomed out" before the steering arm released the wheel to castor. Then, by unhooking the chains on both sides (as John suggested), I was able to get the wheel to castor perfectly in both directions with just the right amount of pressure on the tail of the aircraft. As you might imagine I am ordering new tension springs for the tailwheel. John also discussed with me earlier posts discussing compression springs and their disadvantages. Thanks to John and George for the responses to my original post. OK, now you can laugh.
Hopefully this will refresh the issue with those who have seen it before and teach the lesson of changing too many things at once. I'm so happy to have my tailwheel working correctly again.
N170GA
Thanks to all.
Re: Scott 3200 tailwheel problem
I'm glad we could get the problem solved, Neil! It was easy for a second pair of eyes to see what was happening while you were pushing on the tail.
Last year another guy at our field with an L-3 had a tailwheel steering problem due to compression springs. In a crosswind, with heavy use of rudder, he had pulled out one of the links connecting the tailwheel steering chain to the tailwheel or rudder arm (I can't remember which, but it doesn't matter). When the compression springs bottom out, something's gotta give!
I wonder why we use those things at all -- is there any TW aircraft for which compression springs are stock?
John
Last year another guy at our field with an L-3 had a tailwheel steering problem due to compression springs. In a crosswind, with heavy use of rudder, he had pulled out one of the links connecting the tailwheel steering chain to the tailwheel or rudder arm (I can't remember which, but it doesn't matter). When the compression springs bottom out, something's gotta give!
I wonder why we use those things at all -- is there any TW aircraft for which compression springs are stock?
John
Re: Scott 3200 tailwheel problem
I understand that some Maule's use 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.
50th Anniversary of Flight Model. Winner-Best Original 170B, 100th Anniversary of Flight Convention.
An originality nut (mostly) for the right reasons.
Re: Scott 3200 tailwheel problem
Can anyone direct me to the drawings showing proper mounting geometry on the Scott 3200 tail wheel?
BL
Re: Scott 3200 tailwheel problem
There's one posted in this thread: http://www.cessna170.org/forums/viewtop ... f=2&t=6377blueldr wrote:Can anyone direct me to the drawings showing proper mounting geometry on the Scott 3200 tail wheel?
John
Re: Scott 3200 tailwheel problem
Call Alaska Bushwheel 800 442 8473 and ask them that question. I bet they answer that you install serviceable leaf springs, mount a serviceable Scott Tailwheel and take a photograph. That will be your picture. Seriously, they are good people and have alot of expertise on these tailwheels.