New tailwheel

How to keep the Cessna 170 flying and airworthy.

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slimmorstad1
Posts: 15
Joined: Thu May 04, 2017 9:00 pm

New tailwheel

Post by slimmorstad1 »

Hi All, first I want to say "Thank You" for this great forum and to the many folks that have helped me along the way. I am nearing completion of the restoration of 4526C, hoping to finally take flight next week after 5 years in the making, she hasn't flown since September 1988. One of our last issues is the tailwheel alignment. I have Alaskan Bushwheels, the ears on the tailwheel that the chains hook up to are elevated and should be level we are told. Are there specific shims for this and if so where can I order them. Besides this issue the W & B is all that's left other then the insignia red stripes to be painted on. Again thanks to everyone for all the help you have given me along the way.
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GAHorn
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Joined: Fri Apr 12, 2002 8:45 pm

Re: New tailwheel

Post by GAHorn »

Who told you that and what do they mean by “level”? Level with regard to the ground? The fuselage? Each other?

Don’t get wild and crazy over this... lots of worry is wasted on the tailwheel especially as regards to actual “steering” of the “steerable” tailwheel. Braking plays a large part of “steering” it where you want it to go.
'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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darhymes
Posts: 78
Joined: Fri Jul 24, 2020 7:29 pm

Re: New tailwheel

Post by darhymes »

This is a link to an article that may be helpful since it mentions the Scott 3200 and it’s Bushwheel equivalent, including the raised steering arms:

https://www.kitplanes.com/maintenance-matters-41/
Dustin Rhymes
'55 170B N4410B S/N 26754
'06 G550 “The Silver Bullet”
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Joe Moilanen
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Joined: Sun Dec 28, 2003 5:45 am

Re: New tailwheel

Post by Joe Moilanen »

I see that they recommend using a "wedge" shim to create positive camber, anyone know where you can get these? Mine could use an adjustment towards positive. I replace the main spring every so often but it seems like all of them could use a little more angle towards positive.

Joe
4518C
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GAHorn
Posts: 20967
Joined: Fri Apr 12, 2002 8:45 pm

Re: New tailwheel

Post by GAHorn »

Joe Moilanen wrote:I see that they recommend using a "wedge" shim to create positive camber, anyone know where you can get these? Mine could use an adjustment towards positive. I replace the main spring every so often but it seems like all of them could use a little more angle towards positive.

Joe
4518C

Whoa there, Fellas. The article has a couple serious issues.

As regards the wedge, the author wrote: “ If it doesn’t, you can install a wedge between the spring and the tailwheel assembly to restore the proper angle.”

WHERE did he mention the Approval Basis for modifying that tailwheel landing-gear assembly? (And before anyone goes and makes one of these, remember that if you create a “wedge” then drilling a straight-line hole for that attach-bolt will not be a simple workbench procedure. If the drill-bit is run-through perpendicular to the approach-side of the wedge...it will exit at an incorrect angle on the departure side and place undue stress on the bolt.)
It seems a simple mod, I agree... but his article was intended for “KitPlanes”...but it’s problematical for certificated airplanes with reference to Pt 43 which states that landing gear modifications are MAJOR ALTERATIONS. See CFR 14 Appdx A to Part 43, Para (a) (1) (vi):
Appendix A to Part 43 - Major Alterations, Major Repairs, and Preventive Maintenance
(a) Major alterations -

(1) Airframe major alterations. Alterations of the following parts and alterations of the following types, when not listed in the aircraft specifications issued by the FAA, are airframe major alterations:

(i) Wings.

(ii) Tail surfaces.

(iii) Fuselage.

(iv) Engine mounts.

(v) Control system.


(vi) Landing gear.
...

The author goes on to describe: “ If you need to replace a bearing race, the best way to do it is to heat the wheel up with a propane torch....”

No. DO NOT HEAT THE WHEEL “with a propane torch”. I’m going to go out on the predjudiced-limb I’ve gotten in trouble before and say “That’s Stoopid”. It should be obvious to everyone that heating an aluminum wheel with a torch can damage an aluminum wheel... (not to mention the paint).

Beating bearings In/Out of anything can be and is a common workbench practice but judicious use of the punch and mallet is necessary to avoid damage. A PRESS and bearing-tools (or a common socket) is the preferred method to avoid damage. BEWARE: when using a Press to install the new bearings DO NOT FORGET this wheel is ALUMINUM! (and some wheels are actually magnesium...imagine what a propane torch can do to magnesium.). Be careful not to over-do this as a press can exert such pressures that when the bearing or race “seats”.... any additional pressure can crack/fracture RUIN your wheel! :x

The author also offers what I consider improper instructions on how to adjust the length of steering chains. If the authors’ method is used, full rudder-deflection will not have sufficient tension to “steer”. Further, the author advises to “ err on the side of looseness.” This is contrary to Cessnas’ instruction to remove all slack. (Hint: one reason springs are used in the system is to allow for any “err”.)

I believe the proper method is to adjust the steering chains while the airplane is Empty and tailwheel is ON THE GROUND with the rudder and wheel in alignment (straight ahead) and the chains should be “just-taut” not loose.

The WARNING to not use Maule steering springs cannot be over-emphasized.... yet the author late in the article allows their use. (Remember, he is writing in “KitPlanes”. There is good and legal reason we don’t use data intended for other mfr’s on Cessnas.)

DO NOT EVER USE MAULE-TYPE COMPRESSION SPRINGS IN A CESSNA! They will not improve steering authority....They will only subject your steering system to overstress...and if you have a Serial No. 26505 or later 170, you may cause damage to your aft bulkhead steering-cable pulley system. Did I mention NEVER USE MAULE COMPRESSION STEERING SPRINGS oN A CESSNA TAILWHEEL?

The “upturned” steering arms on the Scott 3200 tailwheel....is properly called a 3200A assembly. It was originally intended for 185 and L19 aircraft. Its’ use on a 170 has been found helpful in Some instances such as when owners found they’d received one of the soft-steel steering arms mistakenly sold for a time instead of the properly heat-treated arms. (Also some users of the Maule springs bent their straight arms and followed anonymous/erroneous advice by well-intentioned folks who didn’t really know what they were talking about. I have no objection to using the 3200A arms on the 3200 tailwheel.... but it really makes no difference on a 170, IMO.
'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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