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Found: Welding Service for Aileron Pushrods

Jim Ellis

Jim Ellis

Well Known Member
There are many discussions in the Forum archives regarding riveting versus welding the W-818 aileron pushrods (DWG-15A). When I built my -9A I used the aluminum rivets called out in the plans to retain the pushrod ends. That worked okay but I did have to make the hole in the rear spar larger to clear the rivet heads. I decided that this time for the -7A I am now building I would have the rod ends welded.

Because I don?t know how to weld and I don?t have any friends that do, I located a company in the Dallas/ Ft Worth area that specializes in just this kind of welding. The company is Aero Space Welders located in Grand Prairie, Texas and its head man is Josh Green. Josh welds certified parts for Lockheed Martin, Northrop Grumman and Bell Helicopter among other big iron builders.

As instructed by Josh, I cut the steel tubing to length, drilled two opposing 1/8 inch holes in the tubing and removed about one inch of the powder coating from the ends. As a side note I did cut the tubing to a slightly greater length than the plans call for. I cut them to 23 15/16 inches to get a few more threads into the rod end bearings.

G50p0d7b.jpg


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Josh removed the cadmium plating from the rod ends to avoid toxic fumes and beveled the mating surface. He then welded the circumference of the rod ends to the tubing and made two rosette welds through the holes I had drilled.

Aunn6Flb.jpg



I was very pleased with the results. The finished pushrods look great but will need the ends repainted. As to strength, I figure if they?re good enough for a helicopter thrashing they?re good enough for me!

If you would like to have this welding done send the prepared parts to Josh. He charges $50.00 for two pushrods plus the cost of return shipping back to you. This is the cost for non-certified parts. He can also provide certification papers if you need them for some reason but at a much higher price. You should call and discuss certification cost with him first. Keep in mind that the actual work performed is exactly the same whether the parts are certified or not.

Here is the contact information you need:

Aero Space Welders, Inc.
Josh Green, President
2470 Doreen Street
Grand Prairie, TX 75050
(972) 988-9121
www.aerospacewelders.com
email: [email protected]

Just for clarification I have no interest in or connection to this company. But I do like to pass on what I have learned to others who may be searching for this kind of help. Josh is a good guy and easy to work with?.besides you don?t have to lie and tell him the parts are for your lawn mower!
 
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Question

Jim,

Looks like nice work. I had the same performed locally and am happy with the decision. I think I paid more than $50.00.

Question: What is a good protective treatment for the threaded end since the cadmium is now removed?
 
My (limited) understanding is that aviation welds should not be ground. Interesting that a certificated shop used a grinder on your pushrods. Makes them look nice, however.
 
Sorry guys I just saw this thread, I?m not going to comment about the parts pictured but after welding one set of these myself and finding it to be a big challenge to get it to go well I won?t do any more of them.

I?m a welder but I recommend riveting these!
 
Sam Buchanan said:
My (limited) understanding is that aviation welds should not be ground. Interesting that a certificated shop used a grinder on your pushrods. Makes them look nice, however.
Click to expand...

You make an interesting point, Sam. I really don't have an answer. I will ask Josh about this the next time I talk to him.
 
welds

Standard practice by the Pitts factory for many years is to "fish mouth" the tube in a v, 30 degrees on each side, no rosette. Grinding the weld is a no-no. I believe this is all covered in the Tony Bingelis books, although I haven't looked at them for a long time.
 
I had mine welded by a guy who does this stuff for a living. They came out great and I'm sure these are much stronger than riveting. He did not grind the welds and I just covered them with the Van's powder coat touch up paint.

849985314_9TMQX-M.jpg
 
bruceh said:
I had mine welded by a guy who does this stuff for a living. They came out great and I'm sure these are much stronger than riveting. He did not grind the welds and I just covered them with the Van's powder coat touch up paint.

849985314_9TMQX-M.jpg
Click to expand...

Sorry those don't look great, it actually looks like he had a time getting them to flow just like I had, and wile they may be stronger then rivets they may not be tougher over time and vibration. Whatever the threaded end is made from it does not play nice with welding, sorry but I would add rivets to those.
 
Grinding those welds is a no-no.

See below:

From AC 43.13-1b

SECTION 5. WELDING AND BRAZING, Par 4-47


(7) Do not file or grind welds in an effort
to create a smooth appearance, as such treatment
causes a loss of strength. Do not fill welds with
solder, brazing metal, or any other filler. When it
is necessary to weld a joint which was previously
welded, remove all of the old weld material before rewelding. Avoid
welding over a weld, because reheating may
cause the material to lose its strength and become
brittle. Never weld a joint which has been previously brazed.
 
Usually when one grinds a weld that means they're trying to hide something...

I find when welding two dissimilar alloys of steel the best rod to use is stainless, instead of E70S2.
 
I don't think anyone is saying the ground weld is "unsafe" in this particular case, just pointing out that that's just not a generally accepted practice in aviation. Heck, even race car chassis are not allowed to grind welds in some classes. They see evidence that you took out your grinder and "cleaned them up", you don't pass tech.

There must be a good reason.
 
rocketbob said:
Usually when one grinds a weld that means they're trying to hide something...

I find when welding two dissimilar alloys of steel the best rod to use is stainless, instead of E70S2.
Click to expand...

What can you hide by grinding? It seems to me that it would be exceedingly hard to hide a porous or cold weld by grinding. I know because I have done it and suffered the 'do-over' for it. :rolleyes:

The welds on the OP's rods look good to me. Although, I wouldn't personally recommend it for any airplane parts, I think the anti-grinding 43.13 guidance is primarily aimed at structural welding (i.e. engine mounts, fuselages, landing gear, etc...). It is concerned with diminishing the strength of the joint. If the subject fittings are normally held in by rivets, it would appear that the strength requirement for these parts is somewhat less than what any good weld would offer regardless of grinding.

Besides, sometimes it's nice to take a decent weld...

663650582_DUu7C-L.jpg


smooth it over...

669249501_aQJMA-L.jpg


and then take it to the powdercoater for a nice, "You made that yourself!? What the heck is it?" finish...

686431084_tgZop-XL.jpg
 
It's worth noting that the tubing and the fitting are both 4130 chrome moly steel. Easily welded; oxyacetylene works great, and was in fact the preferred method for years. Ref. old tube and fabric airplanes.

The nature of oxyacetylene means that preheat and/or post-cooling take care of themselves. Use E70S filler rod, the copper-plated stuff. I used 1/16" rod.

4130 is easy to weld with a torch. So much so in fact, that it's easy to convince yourself that you can weld other steels as nicely, until you try.
 
Question for the OP (Jim) to clarify- did your welder grind the welds as shown in the pics, or did you do the grinding after receiving them from him?
 
Bruce,

Those welds look exactly like ours - and our guy welds nuclear stuff, so I would be more than happy.

It's like primer wars all over again............. :D
 
DanH said:
There's no reason to be concerned with either of the examples. It's a pushrod....the limiting factor is buckling in compression, at a load way, way less than the capacity of even the crappiest weld in tension.

http://www.vansairforce.com/community/showpost.php?p=402323&postcount=57

BTW, the material call for AN490's is 4130....obviously not hard to weld.
Click to expand...

I was going to ask this question. Seems with the small loads on the push tubes (which as you mentioned is all compression) the rivets are beyond adequate. Welding just seems like overkill.

That said I had to hammer my rivets in, those things were way to long to squeeze.
 
Sig600 said:
I was going to ask this question. Seems with the small loads on the push tubes (which as you mentioned is all compression) the rivets are beyond adequate. Welding just seems like overkill.

That said I had to hammer my rivets in, those things were way to long to squeeze.
Click to expand...

I agree the loads are low...but aren't the pushrods under tension when the aileron is deflected downward? I believe Dan's point was that the compression buckling failure mode would be lower than tension failure of even a mediocre quality weld.

My pushrods are riveted, I set them with the C-frame.
 
Sam Buchanan said:
I agree the loads are low...but aren't the pushrods under tension when the aileron is deflected downward? I believe Dan's point was that the compression buckling failure mode would be lower than tension failure of even a mediocre quality weld.

My pushrods are riveted, I set them with the C-frame.
Click to expand...

Only if the aircraft was in hi speed reverse..............................:p

and the aileron was not against the stop.


Sorry Sam, i just had to.
 
Russ McCutcheon said:
Whatever the threaded end is made from it does not play nice with welding
Click to expand...
Van's has allowed for welded aileron push tubes for years, and I'm sure there are hundreds, if not thousands, in service. Perhaps grinding the welds is not aviation appropriate, I wouldn't know, but I've never heard of anyone questioning the integrity welds in general. Why now?
 
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C-frame here too....

... and it worked like a charm.... :)

BTW: this is NOT an attempt to hijack the tread, just to show you how I did it. And I picked up this techique here at the forum.

 
MauiLvrs said:
How do.you.make sure the welded threads aren't to be brittle? ??
Look rather nasty...
Click to expand...

All of the parts are 4130 so why should they get brittle?

They may rust/corrode more after welding (perhaps that is the "nasty" you mean?) so I had mine cadmium plated by an aerospace qualified firm after welding. My welder (also an aerospace outfit) did not grind any of the welds.

The above was easy to do when you live in Los Angeles...:)
 
Jim,

Thanks for posting this thread. For those who want their pushrods welded you gave them another source.
 
Sam Buchanan said:
I agree the loads are low...but aren't the pushrods under tension when the aileron is deflected downward? I believe Dan's point was that the compression buckling failure mode would be lower than tension failure of even a mediocre quality weld.

My pushrods are riveted, I set them with the C-frame.
Click to expand...

gasman said:
Only if the aircraft was in hi speed reverse..............................:p

and the aileron was not against the stop.


Sorry Sam, i just had to.
Click to expand...

You're right, the pushrods are under tension when the aileron is deflected upward.

The plane I built recently had a different aileron horn and I forgot how the RV aileron is designed. High-speed reverse is not recommended in any aircraft..... ;)
 
Toobuilder said:
I don't think anyone is saying the ground weld is "unsafe" in this particular case, just pointing out that that's just not a generally accepted practice in aviation......
There must be a good reason.
Click to expand...

Several, with two at the top of the list; quenching and stress concentration.

Remember, 4130 is an air-hardening steel. It becomes harder, stronger, and more brittle based on cooling rate.

Unless you're very careful, the 4130 in the tiny contact area under the edge of the grinding wheel gets hot....often red hot. Remove the wheel and the red spot is instantly quenched due to all the cold material in the surrounding area. The result is a hard, brittle area.

"Brittle" is often spoken like a cuss word in welding discussions, but all it really means is that the material has a very short (or no) plastic region at the top of its stress-strain plot, usually in return for a higher ultimate strength. For illustration, imagine suspending weights from links made of rock candy (like a candy cane) and a bar of taffy. You'll be able to hang more weight on the rock candy. However, when it reaches its maximum tensile strength it will fail abruptly, without stretching. The taffy may have less tensile strength, but as it nears the its limit it will elongate, stretching before it fails. The rock candy is brittle. The taffy is ductile.

We want our welds to be ductile.

Now consider stress concentration, in this case fine scratches left in the surface of the ground weld. Let's assume Bubba grabs his trusty right angle grinder and "smooths" a weld with a 36 grit wheel. A close look (like 10x) will find the 36 grit scratches are really a collection of surface gouges, many of which will be perpendicular to the load path.

Now combine the two issues, brittle material with a v-notch. Soft, ductile materials tend to flow and reform around a notch, redistributing the load. Hard, brittle materials cannot. The simply crack at the notch. If Bubba was a fool with the grinder, he incorporated both brittle material and notching in a single operation....a marvel of diabolical efficiency.

Back to the ground pushrod in the first post. Consider temperature and finish quality. If material is removed without significant heating it is not possible to quench. If the finished surface is finely polished parallel to load, there are no stress concentrations. The part will be fine. However, from an inspectors viewpoint the problem is that we can't be sure if the material was quenched unless we watched the work. The polishing removes all the telltale surface coloring due to heating.

Like a great many other rules in our reference books, the AC43 prohibition against grinding is based on practical field application at the lowest skill level. It is practical to teach the Bubbas "thou shall not grind". The rest goes to a specialty shop.
 
Russ McCutcheon said:
Whatever the threaded end is made from it does not play nice with welding, sorry but I would add rivets to those.
Click to expand...

However hard you try and however much you think you have got all the cad plating off there is always a residue which as you say, does not play nice with welding.

I tried to get some un-plated ones for my project so I could weld them, but they do not seem to be available.

Andrew.
 
Thanks for the explanation Dan, I had never quite understood that before.

DanH said:
Several, with two at the top of the list; quenching and stress concentration.

Remember, 4130 is an air-hardening steel. It becomes harder, stronger, and more brittle based on cooling rate.

Unless you're very careful, the 4130 in the tiny contact area under the edge of the grinding wheel gets hot....often red hot. Remove the wheel and the red spot is instantly quenched due to all the cold material in the surrounding area. The result is a hard, brittle area.

"Brittle" is often spoken like a cuss word in welding discussions, but all it really means is that the material has a very short (or no) plastic region at the top of its stress-strain plot, usually in return for a higher ultimate strength. For illustration, imagine suspending weights from links made of rock candy (like a candy cane) and a bar of taffy. You'll be able to hang more weight on the rock candy. However, when it reaches its maximum tensile strength it will fail abruptly, without stretching. The taffy may have less tensile strength, but as it nears the its limit it will elongate, stretching before it fails. The rock candy is brittle. The taffy is ductile.

We want our welds to be ductile.

Now consider stress concentration, in this case fine scratches left in the surface of the ground weld. Let's assume Bubba grabs his trusty right angle grinder and "smooths" a weld with a 36 grit wheel. A close look (like 10x) will find the 36 grit scratches are really a collection of surface gouges, many of which will be perpendicular to the load path.

Now combine the two issues, brittle material with a v-notch. Soft, ductile materials tend to flow and reform around a notch, redistributing the load. Hard, brittle materials cannot. The simply crack at the notch. If Bubba was a fool with the grinder, he incorporated both brittle material and notching in a single operation....a marvel of diabolical efficiency.

Back to the ground pushrod in the first post. Consider temperature and finish quality. If material is removed without significant heating it is not possible to quench. If the finished surface is finely polished parallel to load, there are no stress concentrations. The part will be fine. However, from an inspectors viewpoint the problem is that we can't be sure if the material was quenched unless we watched the work. The polishing removes all the telltale surface coloring due to heating.

Like a great many other rules in our reference books, the AC43 prohibition against grinding is based on practical field application at the lowest skill level. It is practical to teach the Bubbas "thou shall not grind". The rest goes to a specialty shop.
Click to expand...
 
Kiwi said:
However hard you try and however much you think you have got all the cad plating off there is always a residue which as you say, does not play nice with welding.

I tried to get some un-plated ones for my project so I could weld them, but they do not seem to be available.

Andrew.
Click to expand...

I had that thought too.
 
Russ McCutcheon said:
I had that thought too.
Click to expand...

Russ-
Have you talked to Van's about this? Since you apparently do a lot of welding for them, I'm assuming they would be interested to hear what you have to say. They've been recommending welding for years as an alternative to rivets and there are many, many RV's flying around with welded rods.
 
rod ends

Pitts has been welding these rod ends since 1969 and Curtis Pitts had welded them for years before that. Never any problems that I have heard of. The v cut in my previous message is not solely for strength it is for proper distribution of stress. Welding straight around a steel tube/fitting is NOT A GOOD IDEA fo any type assembly. If the proper welding technique is used, either TIG of OXY/ACY welding, there will be no air hardening.
I can weld these assemblys for anyone willing to pay round trip shipping.
No certification, just 49 years of aircraft welding experience. I DO NOT GRIND WELDS. email me [email protected]
 
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