Scott Tailwheel.... 3 springs or 5?

[GAHorn]

Well, JDH, you may be right about the validity of all this "technology". Mr. Tim has not yet contacted me with any specifics.
There is also an opinion held by a local restorer (who has seen plenty of these things) who believes that 5 holes were drilled as a manufacturing expediency and are being filled with springs by new-hires on the assembly line. He says he never found 5 springs in one of these things until last year, and therefore believes it's a recent development.

Regarding the solid-filled tailwheel tire,...another solution I've seen for operation in mud (which has similar tendencies to rip off the valve stem) is to go to a bicycle shop or WalMart bicycle section and purchase the solid-filled inner tube replacements for a bicycle tire. These are designed to rid the problem of thorn-punctures. Cut the solid-foam inner tube to the correct size and mount it within the tire and back onto the wheel. It adds a few ounces to the weight. (Needless to say, this is not an approved modification.)

[JTS]

This discussion had been bugging me for awhile, as my scott 3200 (new in 2001)had five dampener springs installed, until I decided to do something about it. I recently removed my tailwheel for cleaning/adjusting and replaced the five old springs with three new ones. The very next time I taxied and flew the airplane I noticed a definite steering improvement right from slow taxi speeds up to takeoff and landing run speeds. (I changed nothing else in the tailwheel, and tightened it upon reassembly exactly the same amount as every other time). So it does make a difference. Go figure

Thought I'd share,
Jody

[bradbrady]

This discussion had been bugging me for awhile, as my scott 3200 (new in 2001)had five dampener springs installed, until I decided to do something about it. I recently removed my tailwheel for cleaning/adjusting and replaced the five old springs with three new ones. The very next time I taxied and flew the airplane I noticed a definite steering improvement right from slow taxi speeds up to takeoff and landing run speeds. (I changed nothing else in the tailwheel, and tightened it upon reassembly exactly the same amount as every other time). So it does make a difference. Go figure

Thought I'd share,
Jody

Jody,
In my opinion you did the right thing! In the past month I had an aircraft come in with a bad tail wheel, disambled it and found 5 springs (that wasn't the only problem, it also had some hand made main spring assyembly that can only be called farmer built!) but the whole system was junk! I couldn't save one item but the pawl! that was still in good shape! I replaced it anyway. Two things need to be addressed 1 that the main nut needs to be tight not over tight but tight. 2 steering spring tention and tire preasure needs to be correct! Also I think 5 years is to long between total dissambly of the tail wheel assyembly! just my thoughts.
brad

[Dooley]

I've been trying to get my 170 to steer better for years as I think it steers about as poorly as any tailwheel airplane I have ever flown. I put on a new fork as my old one had cracks around the engagement spring and had no pin holding the spring in when it was dissassembled. Where did it go? Anyway Alaska Bushwheel sends five friction compression springs with their overhal kit so I put them in. It steers better but I am going to loosen the kingpin nut as I have never had a shimmy problem and it seems like the Rudder pedals have a hard time just overcoming the friction. With the tailwheel off the ground move the rudder,stretch the springs, barely any tailwheel movement. It should steer as well as any other airplane with the same tailwheel.

[GAHorn]

The 170 only utilizes 3 compression springs in the assy.

[bsdunek]

Interesting! The original tail wheel on my 170 had three springs and worked fine. The locking notches finally were so worn, as was the rest of the assembly, I sprung for a new tailwheel. This now has about 200 hours (I have no idea how much time on the ground). At the last annual they pumped it so full of grease it was coming out all over.
I just took it apart and it has five friction springs. They must have changed things over the last 50 years. I'm going to put it together just like it was, as it worked fine before. I have had a little shimmy lately, but the tire is very worn. That's the main reason I'm working on it.

[clayton991]

THREE....just did it. Works great!

[GAHorn]

Interesting! The original tail wheel on my 170 had three springs and worked fine. The locking notches finally were so worn, as was the rest of the assembly, I sprung for a new tailwheel. This now has about 200 hours (I have no idea how much time on the ground). At the last annual they pumped it so full of grease it was coming out all over.
I just took it apart and it has five friction springs. They must have changed things over the last 50 years. I'm going to put it together just like it was, as it worked fine before. I have had a little shimmy lately, but the tire is very worn. That's the main reason I'm working on it.

The proper amount of grease is a funny subject. Some guys tell you to grease it 'til it "spits" at you when you walk by.
Grease is a lot like torque. Just because a little is good, does not mean a lot is better.
Grease the tailwheel about two or three squirts and QUIT! The purpose of the grease is to lubricate the bearings, king-pin, etc., to prevent failure. The grease is NOT intended to flood the clutch-plates (or they will not function as intended....they will slip-and-slide and be absolutely useless.)
Only THREE compression springs are used on the 170. Five are used on heavier aircraft.
(I realize we are all a lazy bunch...but we are supposed to be disassembling, cleaning , inspecting, and re-lubricating our tailwheels every 100 hours whether we think they need it or not. This is when we are supposed to clean out the old grease, inspect bearings, pins, etc. and friction/clutches, and reserviceing the entire assembly. I'll bet that most airplanes go YEARS and several annual inspections without the tailwheel assemblies being completely disassembled, cleaned, inspected, etc etc.)
If you ain't doin' it.... think of all the FUN you're missing out on! (Keeping our airplanes up-to-snuff should be part of our fascination with our hobby. When did YOU last look at YOUR tailwheel?)

[Robert Eilers]

I struggled with tailwheel shimmy. I tried everything to relieve it - short of rebuilding the tailwheel. Rather than rebuild the tailwheel I purchaed the Bushwheel tailwheel. This solved the tailwheel shimmy (expensively). But, I just did not trust myself to rebuild the tailwheel. Now, that I have a fully functioning tailwheel I will try to rebuild the old one. The Bushwheel tailwheel is great. However, I do notice that it is a little harder to steer with on the ground. When the tailwheel disconnects to full swivel there is a deifinite "clunk". Still, I am glad I went to the new tailwheel.

[lowNslow]

(I realize we are all a lazy bunch...but we are supposed to be disassembling, cleaning , inspecting, and re-lubricating our tailwheels every 100 hours whether we think they need it or not.

George, where does it say you have to disassemble these TW every 100 hrs? Do you really do this? Most operators of this TW just squirt grease into them until the dirty grease is forced out and clean grease appears and clean up the mess. While what you suggest is probably a better way to do it, I can't think of many that actually do this. Where I worked years ago we operated 7 Supercubs with 3200 TWs by just greasing till they "spit" and they worked fine operating off a very rough strip 4-5 hours a day making 4-5 landings an hour (glider tugs). I haven't heard of anyone having any problems over greasing, just the geometry problems you mentioned in another thread.

[GAHorn]

...George, where does it say you have to disassemble these TW every 100 hrs? Do you really do this? ...

Take a look at the 100-hour inspection schedule in the front of the Cessna 100 Series Service Manual, 1962 and Prior. Yes.

[bsdunek]

The proper amount of grease is a funny subject. Some guys tell you to grease it 'til it "spits" at you when you walk by.
Grease is a lot like torque. Just because a little is good, does not mean a lot is better.
Grease the tailwheel about two or three squirts and QUIT! The purpose of the grease is to lubricate the bearings, king-pin, etc., to prevent failure. The grease is NOT intended to flood the clutch-plates (or they will not function as intended....they will slip-and-slide and be absolutely useless.)
Only THREE compression springs are used on the 170. Five are used on heavier aircraft.

Well, I put it back together before I read your response, George. It worked fine before, so I'll try it before taking out the extra two springs.
I agree with disassembly occasionally. The wheel bearings are not really sealed like automotive bearings, and I like to clean everything. If would think that the friction damper in the top (the phenolic plate and spring holder plate) would work better with minimum grease.

[lowNslow]

Take a look at the 100-hour inspection schedule in the front of the Cessna 100 Series Service Manual, 1962 and Prior. Yes.

I don't know if I have a different version of the Service Manual, but under 100hr inspection it merely states:

"10. Tailwheel for lubrication, security, cracks, tire for proper inflation, cuts sufficient tread, breaks, and blisters; tailwheel spring, steering and anti-swivel mechanism for sucurity, proper operation, cracks, frayed cables and worn links."

No requirement to disassemble the tailwheel.

[GAHorn]

Take a look at the 100-hour inspection schedule in the front of the Cessna 100 Series Service Manual, 1962 and Prior. Yes.

I don't know if I have a different version of the Service Manual, but under 100hr inspection it merely states:

"10. Tailwheel for lubrication, security, cracks, tire for proper inflation, cuts sufficient tread, breaks, and blisters; tailwheel spring, steering and anti-swivel mechanism for sucurity, proper operation, cracks, frayed cables and worn links."

No requirement to disassemble the tailwheel.

(This is an older thread, but recent review suggests an added comment)

While Item 10 addresses Only the Tailwheel…. Item 7 instructs “ At the first 100-hour inspection and at 500-hour intervals thereafter, remove the
wheel bearings and inspect for cleanliness, rust, cracks, pits, scoring, brinelling,
discoloration, excessive wear, and lubrication.”

The tailwheel has bearings and I do not know how to perform this function without disassembling the tailwheel.

YMMV