One aspect of this issue might be replacing the entire stack instead of only the main spring. If replacing only one spring,...if that spring is slightly overly thick... then it would have less overall impact on fitment.
I have never heard of any failures of the upper leaves in the spring stack...only the lowest/main spring... so that is the only spring I would normally expect to need regular replacement.
Univair tail spring
Moderators: GAHorn, Karl Towle, Bruce Fenstermacher
Re: Univair tail spring
'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.
50th Anniversary of Flight Model. Winner-Best Original 170B, 100th Anniversary of Flight Convention.
An originality nut (mostly) for the right reasons.
- cessna170bdriver
- Posts: 4064
- Joined: Mon Apr 22, 2002 5:13 pm
Re: Univair tail spring
George, I had already purchased a main spring before I discovered the pitting on the upper leaves. The new main spring was with a few thousandths of the old spring, which was to be expected, as it was also a Univair spring I had installed in the 1990s. Two of the new Univair upper leaves were 0.030 thicker than the originals and the third was 0.040 thicker. Since you don’t know of any of the upper springs failing, I feel better about keeping my old ones.
Miles
“I envy no man that knows more than myself, but pity them that know less.”
— Thomas Browne
“I envy no man that knows more than myself, but pity them that know less.”
— Thomas Browne
Re: Univair tail spring
Total replacement may be rare, but this isn’t a part for which salvage should be the only source. Sounds like Univair thinks their parts are correct.
- cessna170bdriver
- Posts: 4064
- Joined: Mon Apr 22, 2002 5:13 pm
Re: Univair tail spring
That’s exactly what Univair thinks, and I have no Cessna data other than IPC part numbers, and only one measured set of old springs, so I can’t refute them. Vintage Aerofab spoke at the maintenance forums at the 170 Convention and claim to have a lot of drawings for the older Cessnas and Beeches, so I’m thinking about giving them a call. I doubt we could put together enough orders to make having them produced cost effective, but they might be able to at least verify the dimensions of the original parts.DaveF wrote:Total replacement may be rare, but this isn’t a part for which salvage should be the only source. Sounds like Univair thinks their parts are correct.
Miles
“I envy no man that knows more than myself, but pity them that know less.”
— Thomas Browne
“I envy no man that knows more than myself, but pity them that know less.”
— Thomas Browne
Re: Univair tail spring
George, to help reduce the confusion here you might want to edit your entry to read, "... leaf spring PNs 0642157, 0642158, 0642159, 0642160." and then delete this entry. Thanksgahorn wrote:If that's not confusing enough, Later 0-1B and subsequent use bracket 0642150-10 and are mated to leaf spring PNs 0642157, 0642156, 0642154, 0642160.
Gary