Q on tail post sleeve for pa-22/20

[violinmaker]

oK--- got the plane home now. Looked at all the pics of 22/20's that have the cracked tail post. This one has never flown since the conversion.
But I will be stripping off the 20 yr. old primer/paint to put on proper epoxy primer. Will be dye-pen testing anywhere suspicious as I go. Also checking for
any hidden rust ( and checking for 819 being previously done- not in log but may have been done as sheet metal looks new--- prob do the blair cutter
maneuver) Now I am working on getting the vert stab unplugged so I can see down into the fin post from above to check for rust---

I think I should sleeve the tail post NOW while I can do it easy. I will be building a rotator for the Fuse---
Here is my question-----
when you cut off the spring bracket--- do you do it in such a way as to try to save the bracket for re-use ?????
OR----- do you sacrifice the bracket to make sure the tubes are not harmed and use a new bracket ?
( are new brackets available ? )

I see some people use a single .060 thick 12 inch sleeve and others do a double sleeve using a 12 inch and a shorter piece of tube- telescoped--
and some others also sleeve the last 4 or 6 inches of the bottom longeron tubes. One fail pic had a crack in that at the 6-Oclock like it is being
pulled in tension till failure.

Is there a source for the tail spring brackets ? or are yall just duplicating a new one ? wondering if Univair will supply that single part ? (!)

Learning as I go---

Tim

[Steve Pierce]

I would get the vertical stab out and slide the a tube in from the top and rosette around the holes that held the tail skid on the PA22.

[Steve Pierce]

If I have to remove the tail spring fitting it gets sacrificed. Univair part number is L1027-02.
https://www.univair.com/piper/piper-...pring-fitting/

[violinmaker]

Thank you steve---
I thought of sliding it in from above----- using the 2 cross holes for rosette--- maybe making 20 more the other direction.... but I was thinking if done that way you would not
have the welded connection between the inner post and the bracket like if you had the bracket off and welded you way from the inner post outward to the bracket.
But-- on the other hand--- im not sure how much in the equation of preventing "flex" there---- having that 360 degree weld going to the bottom of the stack is...…
Don't see how that directly add to the flex prevention------ though it may make the bracket connection better...……
What do you think ? ( I enjoy the welding part---- so that is no inconvience to me---)

I think I would definitely get a new bracket if I have to cut the old one off---- just so I can make my cuts a bit away from the tubes and work the welds down gradually.

Tim

[Marc Davis]

I'm just finishing up this repair based on pictures and comment from Steve, Brian, and others. Not saying I did it right, but here is what I did.

1> I cut off the old spring pad. (new pad from Univaire, Others have the wrong spring angle for a Pacer).
2> I used a 3/4" drill to cut the tailpost out of the bottom cluster.
3> Cut off the tailpost below the top cluster using the AC43-13 diagonal cut.
4> Trimmed the new tailpost to fit. (Wag-Aero is cheapest. All rag wing pipers used the same tailpost part number as far as I can tell). Used rudder to make sure hinge spacing was OK.
4a>Drill holes for rosette welds. I did 6.
5> Installed the new post using a piece of 3/4 X 0.049 as a sleeve. The sleeve runs from above the top cluster (but short of the vertical stab tube) to the bottom of the tailpost.
6> The wag-aero tailpost comes with the rudder stops too long. Trim these carefully so you can just install the rudder. The rudder then clocks the post while you tack it in place.
7> Weld everything up
8> To weld on the spring perch, I used the tailspring as a jig. I leveled the plane and leveled the tailspring as it exits the perch.
9> I measured from each main gear back to the tailwheel to help center the spring left to right.
9a> you have to trim a bit of the tailpost away to get the spring perch to sit flush with the back of the tailpost. If you don't I think the perch might interfere with the rudder.
10> Tacked and welded the spring perch.

Sleeveing from the top was not an option on my machine. The old tie down hook was still inside the tailpost
Sleavign from the top woudl put a butt weld right at a week point. It would be sleeved but not AC43-13.
If you plan to go back country, consider adding gingerbread to allow the tailspring mount area to remain uncovered for inspection.
Consider adding some of the Supercub Alaska mods to the tail section.
The spring perch sits below the bottom of the tailpost by 1/2" or a bit more. You could extend the bottom of the tail post sleeve down to it but getting more than a tack weld in there would be a challenge. In my opinion, not worth it. The spring perch gets a lot of welding as it is.

[Steve Pierce]

Thank you steve---
I thought of sliding it in from above----- using the 2 cross holes for rosette--- maybe making 20 more the other direction.... but I was thinking if done that way you would not
have the welded connection between the inner post and the bracket like if you had the bracket off and welded you way from the inner post outward to the bracket.
But-- on the other hand--- im not sure how much in the equation of preventing "flex" there---- having that 360 degree weld going to the bottom of the stack is...…
Don't see how that directly add to the flex prevention------ though it may make the bracket connection better...……
What do you think ? ( I enjoy the welding part---- so that is no inconvience to me---)

I think I would definitely get a new bracket if I have to cut the old one off---- just so I can make my cuts a bit away from the tubes and work the welds down gradually.

Tim

Good point, might not be needed but probably a lot stronger.

[violinmaker]

Marc--- Thank you --- I think I follow you mostly --- except where you say "

Sleavign from the top woud put a butt weld right at a week point."
If I was to sleeve from the top--- I guess I would drill about 8 rosette holes in the outer tube and maybe leave the inner tube about 3/16 below the outer at the bottom---
then weld a hot bead there --- then fit the bracket to the inner tube leaving a 1/16 gap--- then make another 360 bead around which would fill the gap and fuse all 3 pieces---
IF THERE IS ROOM !!!!! I bet I wouldnt know that untill im right in the middle of it

I am thinking that you wouldnt HAVE to do a diagonal cut and weld there anywhere because you did not cut the outer tube. (in my senario the tube is not bad and needing
replacement) I wont know what my tube looks like inside till I get the vert stab off.

Looks like just doing a new finpost wouldnt be that bad either (and new bracket) If that was needed.

I kind of like the idea of making a sleeve out of 2 thinner pieces and telescoping them together and doing the 43-13 type V joint and rosettes.
Then work the outside down smooth and levle again so the pair fits down inside the finpost. Then do more rosettes--- and fuse all 3 at the bottom---
then weld on the bracket. having 3 layers of tubes there seems like it would reduce the posibility of any single crack releasing the bracket or tailwheel---
The 3 layers would not so easily communicate a crack from one to another. Thanks for the ideas---- be a bit before im doing that--- got to remove the vert fin first.
That thing is really in there .....
Tim

[Marc Davis]

Violinmaker

I missed the fact that your tailpost had not cracked yet. In that case, forget my comment about a butt joint is void. I like the idea of going in from the top. You may have some distortion of the outer tube from the original welding. You might have to get creative about cleaning that out.

My plane flew with the post cracked for some time. There was rust in the crack. It wasn't until I did some rough field landings that I noticed some fabric wrinkling.
Based on that, I would take it ease on the size of the sleeve. You don't want to add any unnecessary wight to the tail.

While a few rosette welds will improve the strength. More will weaken the area. Welds are weaker than the native, un-welded 4130 tube. So, you just want enough rosettes to transfer some of the loads to the inner tube. The majority of the loads will still be carried by the outer tube. Let 43-13 be your guide.

Marc

[violinmaker]

finally got the vert fin out. Good thing I did too. The front tube was mostly rusted off inside the socket. So that will get a repair probably - unless I can find a better used one .
(just as soon NOT pay univair 600$ for a new one.)

On the finpost--- I see at the bottom hole (which didn't get a patch over it) the thickness looks to be about 1/8 or more. so that looks like some kind of sleeve. When I look
down from above--- I can see what I think is the step which may be the end of it--- but judgeing by where that step is-- the sleeve does not look like its more than about 4 inches long. A bit of rust inside there - not excessive.

I see new tailposts are not terribly expensive--- but cutting off the old welds looks like it could be time consuming chore. But I COULD then sleeve to my liking that way.

I may try taking the sand blaster and shooting some sand in there to clean it out to see what it REALLY looks like in there.

Tim

[violinmaker]

Now that Ive gotten the fin out of the tailpost and examined it--- (and cleaned it some) the fin post slides down in there much easier than it did.
I can wiggle it a little bit now-- where I couldnt before. How much slack there is permissible ? I am tossing around the idea of putting in a new tailpost
--- partly so I can sleeve it to my liking--- but I will keep this one if it doesnt look too bad inside-
I thought I could put a 12 ga. shotgun brish in the drill and run it down in there to clean the inner surface to better make a fair judgement of the interior condition. Looks like putting in a new tailpost would be a pretty good chunk of delicate work -- but I could do it ….

How much "wiggle" is tollerable in the fin at the rear socket--- ?

Tim