Tailwheel spring shackle

[LBPilot82]

I've got an A model with what I think is a B model tailwheel spring housing. My housing on the rear of the fuse has two "fingers" that extend forward that are riveted to the fuselage. My IPC does not show this. This leads me to believe it's been upgraded to a B model style. Anyway, since I only have the A model IPC I am looking for the part numbers for the U bolt and shackle plate that clamp the springs at the exit of the housing. (my IPC shows 2 plates and 2 bolts.)
Thanks

[Bruce Fenstermacher]

Here is the page you need with the part numbers. The parts you want are available from Air Repair. Tell them your a TIC170 member.

C170Bpage 54 tailwheelpartspc.pdf

[LBPilot82]

Great, thanks Bruce!

[DaveF]

So, regarding the "Shackle - Spring", part 29-15 ... what is its purpose? To prevent the spring leaves from separating when lightly loaded, allowing the tailwheel to touch the ground when it shouldn't? Or does it keep friction in the spring pack preventing oscillation in flight?

I read somewhere that there should be a shoulder pin staked into the hole in the spring leaf 29-13, extending up through the hole in the shackle, to keep it from sliding. My airplane has no pin, just two holes, but it looks like a short 10-32 socket head cap screw would fit both holes just right, and then the shackle could float nicely and the bolt 29-17 wouldn't have to be tightened so far.

Thoughts?

[GAHorn]

The PN 0542108 spring-shackle is intended to 1) prevent the spring-stack from sliding laterally (sideways) when making turns and 2) to provide a method to attach the 0442145 guard-tailwheel steering chain (which prevents a slack steering chain from slipping beneath the spring-shackle and hanging up in a tight-turn-configuration. When standing on a brake and pivoting in a tight-turn or "pivot"...the inside steering spring will become very slack and may hang down sufficiently to engage the lower ears of the spring-shackle during the pivotting maneuver. Then when the airplane straightens and the tailwheel streamlines, that steering chain is prevented from it's full extension, thereby keeping the tailwheel pulled into a tight turn.)

The spring-shackle can be removed along with it's associated leaf-spring Item 29-13 (PN 0442108-2) and, using an ordinary universal-head rivet, rivetted to the spring, and the formed-head removed by filing so as to not interfere with the 29-12 leafspring (PN 0542105). You might even be successful installing that rivet in-situ, without seperating the stack of springs. There is no great stress placed upon that rivet in ordinary service. It merely prevents the spring shackle from sliding down the entire leafspring set.

Or you may order a new spring-shackle from any supplier who deals in these parts.

[DaveF]

Ok, that makes sense. Lateral movement of the main leaf would probably make the bracket unhappy. Thanks.