Found this on my plane, not sure if I created it (tailwheel shimmy, big rocks) or was like this when I bought the plane.
Is the something that can be repaired?

Well it looks like it at least started before you, looks like someone tried to fix it with stop drilling that crack. That is not a location I would be ok with stop drilling the crack and calling it a day.

Am I also seeing signs of a previous weld repair further along ?

Given the nature of the "fix", stop drilling and what looks like an earlier repair I'd say it time to do the job right once and for all.

That rear bracket needs to be replaced. If it were mine and knowing the places you land that plane, I'd be looking hard at getting the T3 bracket and TW assembly field approved for install.

A1Skinner wrote:That rear bracket needs to be replaced. If it were mine and knowing the places you land that plane, I'd be looking hard at getting the T3 bracket and TW assembly field approved for install.

100% correct, by far the best course of action

A1Skinner wrote:That rear bracket needs to be replaced. If it were mine and knowing the places you land that plane, I'd be looking hard at getting the T3 bracket and TW assembly field approved for install.

I tried to get the T 3 field approval and was rejected.
Does not makes sense to me but it is what it is.

motoadve wrote:

A1Skinner wrote:That rear bracket needs to be replaced. If it were mine and knowing the places you land that plane, I'd be looking hard at getting the T3 bracket and TW assembly field approved for install.

I tried to get the T 3 field approval and was rejected.
Does not makes sense to me but it is what it is.

If your forced to "retain" the original configuration I believe there's an STC or 337 FA to replace the original 170 springs with the taller ones as found on an L19. In addition I think the L19 configuration has one additional leaf or it's thicker material and with a larger arc thereby providing more "give" and greater ground clearance possible.

Larry,

Have you talked with Tom Anderson up at Renton (TLGW). I am sure he could help you.



Josh

Replace the part. Getting a taller tailwheel/tail spring will increase the chance of a tail first landing and hurt takeoff AOA. Avoid tail first or three point landings, Learn to do tail low wheel landings. Much better for the airframe and control. DENNY

I have a mechanic friend who just installed T-3 on a 170B. Came out pretty nice with a big doubler that spans that cracked area. He is an IA too. Send a PM if you want his contact information.

When you replace the bracket look into an L19 bracket. It is a little beefier than the "fishmouth" bracket that you have. It has a slightly different clamping method at the back of the bracket as well. I think where that crack is you need to change it out.

That sucks for sure both the damage and the fact you can’t do the T-3. Truth is I would not be a fan of a T-3 on a Cessna style fuselage without a sh!t ton of reinforcement. I was flying a Rans S-21 with a T-3 and the T-3 overpowered the fuselage as in bent the attachment area

motoadve wrote:

A1Skinner wrote:That rear bracket needs to be replaced. If it were mine and knowing the places you land that plane, I'd be looking hard at getting the T3 bracket and TW assembly field approved for install.

I tried to get the T 3 field approval and was rejected.
Does not makes sense to me but it is what it is.

Motodave,

Sent you a PM.

T

I got a nickel saying you look at the aft bulkhead there’s cracks in it. Tail is definitely the weak link on the 170.

I've heard rumors that the T3 is very close to getting their STC approved for the 170.

Pundy wrote:I've heard rumors that the T3 is very close to getting their STC approved for the 170.

Me too - for the past several years. I really hope they do it, but I wonder if there s a big enough market to cover the cost.

I don’t know if there’s a big enough market, and I have zero experience with the T-3 setup. But IF they got it approved and I owned a 170, I’d buy one in a heartbeat.

The stock tail spring on all the 170s is waaay too wimpy for anything besides pavement and maybe not that. There are a lot of forces back there, including twisting, and the tail structure isn’t solid enough to take a lot of abuse.

I replaced the main leaf on my 170s spring stack with a L-19 main leaf. Removed the shortest leaf to fit, since L-19 leaf is thicker. That stiffened up the spring stack just about right. Field approved, back when you could.

But, looks to me that whole mounting needs to come apart and replaced as needed.

MTV

Utah-Jay wrote:That sucks for sure both the damage and the fact you can’t do the T-3. Truth is I would not be a fan of a T-3 on a Cessna style fuselage without a sh!t ton of reinforcement. I was flying a Rans S-21 with a T-3 and the T-3 overpowered the fuselage as in bent the attachment area

There has to be more to the story than that! The T3 soaks up the bumps and rocks so if you bent something its because you whacked the heck out of something. Had it been a stock tail spring I am guessing the damage would have been much worse.

I can say that the T3 on a 170B is night and day difference just like putting it on any other plane. This is the kind of thing that really fires me up. I see it as a safety issue. If I can do something that removes serious abuse from the airframe, it is making things safer. I should not have to beg for permission to make my airplane safer.

What is the down side as far as the feds are concerned? I can break a stock tail spring probably easier than the T3, the Stock tail spring is much rougher on the airframe than the T3. Why would the feds even have to think twice about approving it, other than just being complete aholes.

The one issue I’ve heard of with a T-3 was in twisting, and it sounds like that’s what he was describing. The T-3 is Very rigid, so any twisting forces are going to be transmitted directly to the fuselage. A spring MAY actually absorb a bit of twisting force.

But, I do agree that those strut type systems do a way better job of absorbing direct up/down forces.

MTV

if its twisting motion, you can chalk that one up to pilot technique and not the fault of the T3. Not sure what the count is on T3's being flown, but I am sure stock tail springs have bent and twisted more fuses than a T3 has.

I can only truly speak on the 2 I have flown and I know for a fact that there is a hell of a lot less load transmitted to the fuse in all areas of ground ops with the T3 versus without, especially when playing in big rocks on gravel bars. Hell even taxing on pavement with BBW its night and day difference going over the cracks in the pavement.

I won't be taking mine off anytime soon, I can promise you that.