• If You Are Having Trouble Logging In with Your Old Username and Password, Please use this Forgot Your Password link to get re-established.
  • Hey! Be sure to login or register!

Tail wire clevis mystery

Bugs66

Bugs66

Registered User
Spokane WA
I am installing my stabilizers on my experimental Cub and am fitting my flying wires.

I am curious why the bolt for the horizontals is 3/16 (AN3) and the holes for all the clevis' are .266? The fin has the .266 hole but not the horizontals. So am I to presume that the AN3 bolt is to have all that play in a .266 hole? I checked the parts catalog and that appears to be true. Drawing 40521 for the clevis' show a .266 hole no matter what clevis you have.

Comments or clarification?

Thanks for your help!
 
There is a bushing. I think the idea is for there to be some pivot action there as the stab is trimmed.
 
Im not sure but you may want to see what these two piper part numbers are, 40131-00 washer and either 82732-72 or 80012-06 bushing. It may or may not help you.
 
Last edited:
There is a square/bent washer at the top as a reinforcement. Clyde Smith in cubclub mag warns to not fly without them as the clevis tends to crack without them. And I believe the bushing was brass. But I could have a faulty memory on that.
 
The bushings I have seen are steel. We lost one and the only way I found it was with a roofing magnet all over the hanger floor. :oops:
 
There is a square/bent washer at the top as a reinforcement. Clyde Smith in cubclub mag warns to not fly without them as the clevis tends to crack without them.
Click to expand...

A couple of years ago one of my tailwire attach brackets cracked because the square'bent washer was not there. Thankfully Steve Pierce was able to get me a replacement (via Cathy) at the fly in and fix it.
 
Thanks for the tip on the bushing. I didn't realize until I looked at the parts catalog again. There is indeed bushing 82732-72, which is .25 OD, .191 ID, and .156 L. Not sure how that would aid in pivot action but I guess it does?

I plan to put the square reinforcement on the fin too.
 
Bugs, That was just told to me by an old timer. When I thought about it I could see some sense since the whole stab moves and the vertical is fixed.
 
I dropped one of those lil' square/bent thingies too, my guru-neighbor said "find it or replace it, the clevis WILL break without".

AC Spruce p# 05-07555 "Tail Brace Hdwe." $27.80
 
The bolt clamps down on the bushing, and allows the clevis to swivel.

I still want to hear about what happens when a tail brace wire breaks in flight. Is it fatal?
 
On Drawing 13386
Upper_Tail_Brace_.jpg

Horz_Tail_Brace_Wire_Fitting.jpg
 
I have found several clevis's broken on one side but not both. I know of an experimental Clipped Wing Cub that broke the whole thing. It has been a long time but if I remember correctly the rudder balance bent 90 degrees. He did get it back on the ground.
 
3/16" of the proper size 4130 tubing, about .04 cents. Owner fabricated.
Someone splain to me how the vertical bushing will allow the horizontal stabilizer to move around it when the stabilizer movement is also vertical?
If the stabilizer movement was horizontal, I'd buy it, but.......
 
TJ, I agree. This guy gave me a hard time because I tightened the bolts. He said they were supposed to be loose so it could rotate. I have played with it and can't figure out how it would rotate around that bushing.
 
Yep, it's correct.
Just ask Lee, I bet he knows better than that!
When you crank in trim, and move the front of the stabilizers up/down, the tail wires twist. Everything else should be tight.
 
The bolts are supposed to be tight. The .004 cent bushings are ever so slightly longer than the two straps of steel, leaving the freedom to move a bit. I don't think it has anything to do with trim; it probably has to do with damping harmonic vibrations at someplace other than the threads. If you can move the clevis up and down, the bushings are too long. In a long hard climb, glance at those tail surfaces - I think you will see what I mean.

When I oil my hinges, I never forget a drop on each part of those wires. Makes adjustment and disassembly lots easier.

So, so far no fatalities from any structural failures except for lift struts? Have we ever had a wing fail? Seems to me a list of the things that have failed in flight with an unsuccessful return to earth would be a good thing to have on a preflight.
 
Seems to me a list of the things that have failed in flight with an
unsuccessful return to earth would be a good thing to have on a preflight.

Great point, Bob,

That question was brought up a couple of times in the thread
about the 2000# weight increase; but was never answered.

Joe
 
I have personally seen four (4) broken jackscrew shafts.. (I wasn't flying the airplane when any of them happened.)
The airplane was (ab)used for float training.
 
I was out doing loops and spins in a 1941 J-3 Cub back in the early 1950s and when I returned to RDU one of the tail wires was broken at the top and had punched a bunch of holes in the rudder. That's all! I didn't notice anything wrong until I saw it after landing. ...Clyde Davis

I related this on another thread a long time ago. ...cgd
 
bob turner said:
So, so far no fatalities from any structural failures except for lift struts? ........Seems to me a list of the things that have failed in flight with an unsuccessful return to earth would be a good thing to have on a preflight.
Click to expand...

lift strut attach brackets on wing..... bent from being tied down to original tie down/strut in high wind... then breaking off later in use, atlee has a beef-up.

occasionally look up struts to see if brackets are in-line with struts still...
 
Somebody, it might have been either Jr or Jay, told
me that the PA18-180 exhibits a problem with the jackscrew.
Seems the stabilizer takes a hell of a beating with
that engine.
I haven't seen evidence of it yet; but who would
see a stress crack in a grease covered apparatus
without a magnaflux exam?
 
Cajun Joe said:
Somebody, it might have been either Jr or Jay, told
me that the PA18-180 exhibits a problem with the jackscrew.
Seems the stabilizer takes a hell of a beating with
that engine.
I haven't seen evidence of it yet; but who would
see a stress crack in a grease covered apparatus
without a magnaflux exam?
Click to expand...

Joe-

It is best to use Graphite in that "grease covered apparatus" so dirt does not stick to it and erode the parts.

Tim
 
Thanks Tim,

I've been using that lithium white with the volatile carrier
to try to keep the water spray from washing it off,
and yes it does gum things up.

What application is graphite available in. As in how
do i get it on the shaft??
 
Multipurpose Graphite Dry-Film Lubricants
It goes on as a liquid but the fluid evaporates after application to leave a long-wearing dry graphite film that won't attract dirt.
Quick-dry lubricant lets you access every nook and cranny of locks and other fine mechanisms. Aerosol has a female stem.
Brush-on lubricant is extremely durable and resists moisture and salt. Apply with a brush.
Sprayable lubricant is thin enough to be applied with a spray gun and can cover a large area quickly. For HVLP spray guns, see 77745T and 9383T on page 2084.


www.mcmaster.com and type in "graphite lubricant"
 
You must log in or register to reply here.

Similar threads

Larry G
Tail brace wire assembly
Replies
11
Views
6K
C-YQK
C
tedwaltman1
Piper Clevis (tail wire brace bracket) part failure
2
Replies
55
Views
33K
mvivion
mvivion
F
I'm missing .037 on tail wire assy.
Replies
2
Views
2K
bob turner
B
Bob Breeden
180 horizontal stab is loose...
Replies
18
Views
7K
180Marty
180Marty
TVATIVAK71
Tail brace wires
Replies
5
Views
6K
DENNY
D
Back
Top