Have two small-ish cracks in the steel bracket for the tailspring. Pics attached...
I'd like to weld them, rather than replace the whole bracket. Thoughts?
Anyone else try something similar?

I would strongly encourage the replacement of the bracket.

Thoughts on leaving it as it is if the cracks do not spread past the stop drill hole?

fly8ma wrote:Thoughts on leaving it as it is if the cracks do not spread past the stop drill hole?

I guess that would be one way to do it...

If steel, I have heard of folks welding but I’d remove it from the ship first.
If you have to go that far why not replace?
On my C-140 I had a similar issue ( crack in the aluminum t/w leaf spring bracket) and just replaced it.
Wasn’t hard to do.
Cheers,
Dave

Don't weld it

I’d probably replace it. That said, talk to your mechanic.....he or she is the one that should be signing it off, and YES, that kind of repair requires a sign off. If they feel it can be safely welded....I might.

MTV

Bigrenna wrote:
I guess that would be one way to do it...

I've heard that somewhere before

To do a decent job welding it you would need to take it off anyway. I think there is an L19 bracket available that is a little bit stronger.

and if you are taking the bracket off, you might as well change it.

I have the same issue with the Bolen conversion on my 172, the radius is way too sharp. every Bolen conversion i have seen has cracks in exactly the same place. I looked at the Stoots conversion, which is the L-19 bracket, but ended up with a modified "bolen" with a smoother radius and a reinforcement dubbler


FWIW, i flew with stop drilled cracks in mine for over 10 years, before finding a solution. your mileage may vary.
If i had to do it all over from the beginning, i would have used the L-19 bracket, no reported issues i could find, but it would have been 3-4 times more expensive to make that change at this point.

Slowhawk,
Thanks for the post. That is a beefy upgrade. Was it a Field Approval or STC or just a logbook entry?
Isn't there some Cessna data-service bulletin/service instruction for this problem on the 170's?
Again nice work. You went the distance.
Cheers,
Dave

logbook entry, owner supplied part. it is from the bolen blueprint, with a modified radius, the dubbler is extra

My 170B had over 7000 hours on it when I sold it. And, it had been used HARD before I bought it. Never had any cracks in that part of the tail. I did, however switch the main spring leaf to an L-19 main leaf, and removed the smallest leaf, to give the spring a bit more "backbone". I've seen more than a couple of those springs break at the tailwheel.

Mine was a logbook entry, I believe, though it may have been field approved. Can't recall.

Some very knowledgeable mechanics I know have not many good things to say about the Bolen conversion tailwheel attach. That beef up above looks like a reallly good solution.

I'm keeping an eye on mine, but might be better off to be proactive, and add the beef up.....or better yet, add a TK unit to soften up the stresses.

MTV

after paying for the fix, i would have rather been proactive. Didn't know it was an issue till after the fact.

I'd recommend replacing over welding. Welds are themselves stress risers. In your pictures you've already lost about 1/2 of the cross section of that part with the cracks you have. I'd replace ASAP.

Jon,

Those brackets are made of aluminum, not steel. If you can determine the alloy used it's possible to weld it, if its 2024 it is not weldable, if 6061 it is.

I would personally replace it, the brackets are cheap and are the same as used on the L-19. You will find a few for sale on ebay.

I'll throw my hat in the ring.... id also say replace if it were me. Stop drilling does stop the crack, but there's still lost strength on the bracket where the crack is. Welding may fix it, but without re-heat treating the entire bracket, you are introducing new stresses to the metal that it was never designed for. The cost of replacement is a lot cheaper than the cost of repairs when the tailwheel departs the aircraft... just my $0.02...

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