The International Cessna 170 Association

Good morning,

I’ve owned this 170A for a few months now and I’m trying to get all of the kinks worked out. Currently I’m focused on the tailwheel. I have a few concerns with it: 1. It appears to have small cracks on both sides at the radius where the tailwheel mounts to the airframe. 2. It has significant areas of corrosion. 3. I’m fighting a shimmy that I haven’t been able to fix.

1. Can these cracks be welded successfully?

2. Does the corrosion look bad enough I should consider replacing it?

3. I’ve read a lot of posts about tailwheel shimmy. I’ve played with tire pressure and chain tension with no luck. It appears to me that the caster angle is correct but it’s could be wrong.

I’ve attached pictures of the problems areas. If anyone has any advice, I’m all ears.

Thank you!

MOD note: I corrected the orientation of the photos.

Hello and welcome to 170A ownership.

You have the original tailwheel bracket. Cessna came out with a service kit (SK 70A52-4) to upgrade the steel tailwheel bracket to an aluminum that has a "fish mouth" attachment to the tailcone. Your cracks definitely need to be addressed as they will only get worse and may start to grow quickly. I would consider going with the new tailwheel bracket (you can see the two versions in the 170B parts catalog or in the service kit instructions) . I believe there are some L-19 versions available on Ebay. That might be the route to go, but I'll let those with more expertise chime in on that. I'd also recommend searching this site for info on that kit.

http://www.cessna170.org/forums/viewtop ... 42&p=84173

It also looks like you need to replace your main leaf spring as well. A new one will have an additional bend that will correct your tailwheel caster angle. Yours appears to be like mine was where the leaf spring has "flattened" out over the years. That will help shimmy.

Doug

Maybe your castor problem is due to your tailwheel being mounted upside down

Sorry about the pictures. I can’t figure out how to flip them around. Makes me feel old when technology gets the best of me.

I searched using the term Fishmouth and found a ton of info. Thanks for the lead on that one.

I’m still a little confused about which part numbers I should be looking for. Am I better off installing the L19 “-3” or the Birdog “-10” bracket? There are some L19 brackets on Ebay for around $200 that are NOS. Apparently Air Repair has brackets as well for around $700 (not sure which ones). I would like to install whichever one works with standard 170 parts to simplify things.

I appreciate the patients with me. I’m still getting the hang of 170 ownership.

Hi welcome to the club.

I had the same cracks in my 170A bracket and I'm in the process of upgrading to the fishmouth bracket. In my case, there was a lot of wear and tear on some internal parts. I'll be more than happy to talk to you about what I'm going through. sippler@vaa16.com 816 tree 0 fife 82 niner 0
Ron Sipple

N9206A?

Ryan Smith wrote:N9206A?

Yes sir. The one and only.

Contact Pete Jones at Air Repair and tell him you’re a 170 Assocn’ Member for your discount for the ENTIRE KIT and convert yhour airplane to the later/better system.

I’ve got time in that airplane when it was in North Carolina. Wonderful flying airplane.

Most of woes with shimmy stopped when I learnt to put it down at a slower speed. Started all over again with a baby bushwheeel, and again its a speed thing. If it does shimmy pushing forward on the yoke will stop it. I think a good high speed tailwheel shimmy can put a huge amount of stress on the whole unit, even up to the bulkhead on a later 170 with the "improved" steering cables.

All that vibration might have contributed to the bracket cracks.

I spoke with Pete at Air Repair and he got me all set up with the required parts and gave me a significant 170 Association discount. After speaking with Ron, who had very similar damage, I’m really hoping I don’t get her opened up and find a whole new can of worms. I debated trying to have it welded and limp it along but I think I’m just going to bite the bullet and tear it apart. Especially since the shimmy has been getting progressively worse. When I first started flying the plane it only shimmied every once in a while and I could get it to stop by pushing forward on the yoke a bit and sometimes a tiny amount of brake. Here lately it happens almost every time I land on pavement and nothing I do makes it stop. I don’t want to damage her any farther so unfortunately she’s going to be parked for a bit.

Thanks for all the tips. I’ll update this post as I start working on her.

Have been down the same route as you and blindly got my self out of trouble. [long before I joined the 170 club] It’s the rake angle of the pivot on the tail wheel that causes the shimmy . A new set of springs correctly modified [sharp edges rounded off ] is a must . Originally I didn’t know about the “new” fish mouth fitting . However somebody previously to my ownership had welded up all the cracks and placed strengthening plates over the cracks and welded these in place . It was done so well I had thought is was a normal factory part. It’s worked so well for the last 20 years and “O” boy have I dropped it into some horrible places. [unintentionally of course]. My spring pak is a dogs dinner but it works . It should be replaced again as I have 5 springs . I always grease my swivel point and tail wheel after each flight . But looking at your photos I would be replacing that tail wheel attach point and springs .

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Bhbackcountry wrote:I spoke with Pete at Air Repair and he got me all set up with the required parts and gave me a significant 170 Association discount. After speaking with Ron, who had very similar damage, I’m really hoping I don’t get her opened up and find a whole new can of worms. I debated trying to have it welded and limp it along but I think I’m just going to bite the bullet and tear it apart. Especially since the shimmy has been getting progressively worse. When I first started flying the plane it only shimmied every once in a while and I could get it to stop by pushing forward on the yoke a bit and sometimes a tiny amount of brake. Here lately it happens almost every time I land on pavement and nothing I do makes it stop. I don’t want to damage her any farther so unfortunately she’s going to be parked for a bit.

Thanks for all the tips. I’ll update this post as I start working on her.

Hi Patrick, Let me know if you need the lower skin. I made a couple of these.

Finally got the old girl tore down. Found a few hidden problems but nothing too major. Need a rear bulkhead and should be ready to go back together.