Tail brace rods.

[t30mg]

Well, we have the paint on the fuse and tail. Looking through the parts, I've found the tail brace rods are missing.

Any extras out there?

Anybody made their own and have the specs on them?

Thanks.....
Aaron

[N74DV]

Re: Tail brace rods.

Anybody made their own

Not likely and if anyone has made their own I'd be leery of flying in the aircraft. Not many can make proper flying/tail brace wires because they require rolled threads (not die cut threads). Don't be tempted to cut threads on steel wire. Have the threads rolled (expensive) or use braided cable with swaged or nicopress ends (along with proper paperwork of course).

[VictorBravo]

Re: Tail brace rods.

Well, we have the paint on the fuse and tail. Looking through the parts, I've found the tail brace rods are missing.

Any extras out there?

Anybody made their own and have the specs on them?

Thanks.....
Aaron

I would not be afraid at all to have them made. You must use rolled threads, as mentioned by DJ. However, there are companies that roll threads... it's not THAT rare to find. Get yourself some steel rod of the right diameter, and have the threads rolled. This is a PERFECT venue for an "owner produced part" where the owner "manages" the production by an outside vendor. It's legal and it is just exactly the correct example for this rule.

I would guess the rods were originally mild steel, but perhaps this is also a good time to substitute 4130 because of toughness. This is a question for an engineer, but I SUSPECT that stainless would be plenty strong and eliminate the corrosion problem most of us have with tail brace rods.

[Robert Lees]

Re: Tail brace rods.

Univair have them: Link

[Hank Jarrett]

Re: Tail brace rods.

I am pretty sure if you check the archives you will find that the wires DO have cut threads. I AM an engineer with a structures background and if I remember correctly I thought the threads were rolled too. There was a lot of discussion on the "rolled" or cut threads several years ago. I am pretty sure Forrest was the one who set me straight. Rolled threads are stronger, but they were probably not cost effective originally so Taylorcraft just went to larger diameter and cut threads.

I haven't looked at the tail wire threads for a long time but the easy way to tell cut from rolled is to just measure the diameter or the wires. When you roll threads you upset the metal. The OD of the thread gets larger and the ID gets smaller (the correct term is actually Major Thread Diameter and Minor Thread Diameter). Just measure the diameter at the threads and on the shank right next to them. Threads larger than the wire, they are rolled. With cut threads you actually remove metal that causes stress concentrations at the bottom of the threads where the wire is more likely to break. If the thread diameter is the same or smaller than the wire, they are cut. There is nothing wrong with either one if they are sized right.

The most important part is that you should NOT make your own wires. They are available from several manufacturers. We really aren't supposed to be making owner produced parts when they can be bought as legal parts from aftermarket suppliers.

I bought new wires for the 41 (the wires are different lengths for different years, ORDER THE RIGHT ONES!) because even though I could get them made (cut or rolled) I wanted yellow tagged parts for something that could cause a tail surface to fold up if it broke. I don't want to die in order to save a few bucks.

If my Taylorcraft logo on my compass fails it isn't going to kill me. If I was doing an STC for new tail wires I would use rolled threads and make them from stainless steel. It's more expensive, but a lot safer. The wires would have to be re-sized to maintain the original safety margins, but that isn't a big deal. The idea of cut threads on a critical, regular steel wire, that is under the tail where it rusts and pits kind of scares me. How often do YOU check the lower tail wires on YOUR pre-flight? I check mine before every flight, but I'm anal. Do you even have your A&P take them off and inspect the threads bases for pits on the annual with a magnifying glass? Yea, I do. That is where they will break, UNDER THE NUT where you can't see it! Don't forget YOU ARE NOT ALLOWED TO PUT THE WIRES BACK ON!!! I do it as part of an ANNUAL and my IA checks that I did it right. The Feds frown on you taking the wires off your tail.

This is one of those things we need to add to our recommended inspection list. We don't need to loose someone or have the FAA to ground all of us because of a tail failure from a corroded tail wire failing. Go look at your wires!

By the way, my new wires came with a conversion coating and I primed and painted them prior to putting them on. The old ones aere just conversion coated with NO PAINT!!!! After rigging them, WITH THE JAM NUTS!! (Can't tell you how many planes don't have the jam nuts) and yes, I couldn't find jam nuts for my wires and bought them from someone in the tribe. The jam nuts aren't going to kill you if they fail and were NOT available. Besides, remember, I look at the wires every pre-flight. After the rigging was finished I used a small brush to paint the fittings and threads to protect the metal exposed by the fittings and jam nuts removing the paint. It's pretty easy to see cracks in the paint.

My suggestions,
Visually inspect your wires NOW! THE jam nuts are REQUIRED!!!
BUY NEW WIRES if yours have ANY corrosion damage
Check the threads at the next annual
Protect them with good corrosion prevention
If there is any doubt, BUY NEW ONES
DON'T just go out and do any removal or rigging without getting your A&P! He is neded to put the jam nuts on, unless you know a way to put them on without removing the wires.

While you are back there take a real close look at your tail wheel. Leaf springs in the right configuration? Spacer tube in place in the fuselage at the front bolt? Steering springs hooked up right? Tail tire in good shape? Everything tight and secure? How about those lower longerons? Good time to poke around with a screw driver for rust in the "Taylorcraft Terrible Triangle".

See, told you I was anal.

Hank

Hank

It's winter, good time to put hands on our babies and make sure they are ready for spring.

Hank

[t30mg]

Re: Tail brace rods.

The univair link is just what I needed! Thanks.
I guess the brackets are gone too. Can those also be bought?

Hank, what is the spacer at the front bolt of the tail spring? This also was not on our plane when we picked it up.

Thanks for the help....

Aaron

[Robert Lees]

Re: Tail brace rods.

Aaron:

I have a collection of nipples and jam nuts to do a Taylorcraft or two. The Univair wires have the same thread form, so these would fit. I also have a few straps (brackets...is that what you mean?), but probably not enough to do one Taylorcraft...but it would be a start for you.

If you can work out what you need, let me know.

[astjp2]

Re: Tail brace rods.

Burls aircraft sells them under a pma or stc, look him up on the web. Tim

http://www.burlac.com/

[t30mg]

Re: Tail brace rods.

I guess I would need whatever the wire braces thread into that connects them to the vertical and horizontal stabs. I have the threaded (bosses??) on the stabilizers, but nothing to go in between them.

If you have anything that would help me, I'd be glad to buy them from you.

Thanks again....

Aaron

[Hank Jarrett]

Re: Tail brace rods.

Aaron,
On my 41 there was just a couple of steel washers. The 45 had the original square piece of steel with a hole in it. You need the spacer to keep the top and bottom springs parallel. Notice that the top spring runs from the front bolt to the strap. The second spring runs from just aft of the washers down to the tailwheel. The third spring is the only one that runs from the front bolt all the way back to the tail wheel. If you have two springs from the front bolt to the tail wheel when you push down on the tail (like when the tail drops on a normal landing) there is a shearing effect and one of the two bolts eventually gets sheared off. Lots of Taylorcrafts out there with the springs in the wrong order or the wrong springs. These are planes just waiting to loose the tail wheel assembly. I learned this one the hard way. It WON'T last with the springs wrong. If they are wrong, you are on borrowed time. Without the washers the top and bottom spring are pinching the middle one and the same thing can happen.
Hank

Yes, I also like cotter keys better than self locking nuts. Very few elastic or JAP nuts on my planes.

[VictorBravo]

Re: Tail brace rods.

I wanted yellow tagged parts for something that could cause a tail surface to fold up if it broke. I don't want to die in order to save a few bucks.

I would use rolled threads and make them from stainless steel. It's more expensive, but a lot safer. The wires would have to be re-sized to maintain the original safety margins, but that isn't a big deal.

Question based on idle curiosity: How much loads are on those wires, and how much strength does the original style steel rod have? In other words, how far overkill are the original brace wires?

[Hank Jarrett]

Re: Tail brace rods.

Not knowing the original spec I can't tell you the loads, but the standard wires are WAY over strong for any loads that would cause failure of other parts in the tail. That is the WIRES are way over strong. The cut threads will cause huge stress concentrations and any failure will come in the threads. I have seen tail wires with some pretty nasty corrosion pits that were flying just fine and the lower ones can take quite a hit from debris or obstacles on the ground. Ever seen anyone grab the top wires to pull an airplane back? Makes my hair stand on end, but I have seen it done to many times to count.
A few things to remember since I can't answer directly without looking at the original factory design calculations.

The horizontal tail lifts DOWN in normal flight. Moving the elevator down can reverse the force if it is pushed far enough (loading the lower wires), but if a top wire fails the stab will probably bend and fold down followed by the plane diving into the ground with a locked elevator. Not a good day.

If you don't have the jam nuts on and tight, vibration can cause the threaded fittings to turn in the strap fittings changing the rigging or the wire can come completely loose. Same bad day.

If you don't put your hand on the wire (checking for a low "thrum" when plucked) and check each jam nut for not being loose, ALL 8, you won't know if the nuts are tight and the wires rigged. Leading eventually to the "bad day".

If the wires have pits along the length, there can be stress corrosion as bad or worse than the cut threads cause, leading to the "bad day".

If there are pits, cracks or corrosion under the covered part of the threads, you can get an "unexpected bad day", and you aren't allowed to look at that part without your A&P! Take them apart at the annual and LOOK AT THEM WITH A MAGNIFYING GLASS! Then treat them with a coating to keep water out and prevent corrosion.

As far as I know there hasn't been a failure of a tail wire that caused a crash. Of course there hadn't been a strut failure that caused one either, and from what I have seen there STILL hasn't been a strut failure, but that didn't stop all of us from being grounded. This is easy stuff to check guys (except the thread inspection). Just get used to doing it on every preflight. You need to be checking the tail wheel and springs on every preflight anyway, and a failure there is likely to only mess your pants and bend the plane.

Hank

PS
To get to the basis of Bill's question, Forrest would need to answer, but if I was making SS wires with rolled threads and didn't have the original data I would just do a hardness and conductivity test on the original wire to determine it's tensile strength (along the middle part) then select a SS wire that was at least as strong and roll threads on it. That would make the new wires at LEAST as strong along the length and MUCH stronger in the threads. It would require all new end fittings and an STC, but would probably never need be a worry again.
By the way, I would also change the design of the end fittings so they could be safety wired and couldn't vibrate loose. The fitting also needs a cross hole to insure minimum thread engagement.

[Robert Lees]

Re: Tail brace rods.

Aaron,
On my 41 there was just a couple of steel washers. The 45 had the original square piece of steel with a hole in it. You need the spacer to keep the top and bottom springs parallel. Notice that the top spring runs from the front bolt to the strap. The second spring runs from just aft of the washers down to the tailwheel. The third spring is the only one that runs from the front bolt all the way back to the tail wheel. If you have two springs from the front bolt to the tail wheel when you push down on the tail (like when the tail drops on a normal landing) there is a shearing effect and one of the two bolts eventually gets sheared off. Lots of Taylorcrafts out there with the springs in the wrong order or the wrong springs. These are planes just waiting to loose the tail wheel assembly. I learned this one the hard way. It WON'T last with the springs wrong. If they are wrong, you are on borrowed time. Without the washers the top and bottom spring are pinching the middle one and the same thing can happen.
Hank

Yes, I also like cotter keys better than self locking nuts. Very few elastic or JAP nuts on my planes.

Not quite sure whether you posted this in the right thread, Hank, but whilst we're on the subject, some leaf springs have a slot to permit movement...see the bottom of this picture.

Rob

[Hank Jarrett]

Re: Tail brace rods.

The break or a slot should work, but I have never seen them personally. The key is there can't be a solid lock between any two leaves. Not sure I like the slot since you can't tell you don't have a pair of the bottom springs without taking them apart.
The only reason I put the spring discussion with the tail wires is I always look at both at the same time. As you have noticed, there is another thread on the tail springs. Both topics should be looked at by every Taylorcraft owner. Cheap insurance against catastrophic consequences.
Hank

[flyguy]

Re: Tail brace rods.

While we are talking about the safety of the tail wires, what about those two little tabs on the bottom where the "brackets" attach. I can see those having corrosion or cracks under the paint and or dirt.

I am pretty sure that I found that the tailwires originally were 90K lbs/in2 steel with rolled threads. Years ago I was considering cad plating mine. Bad Idea, without post plating out-gassing treatment. Don't remember where I got the strength information, but it was pretty solid and I get this feeling that the factory was involved. We're talking in the 80's.

Anyway check those tabs with all the other stuff.
DC