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RV-6A Step Crack

Ron Lee

Ron Lee

Well Known Member
A few days ago I noticed a crack on the inside of my step just under the weld that attached the long near-vertical portion of the step with the flat plate that attaches to the fuselage side.

Here is a pic:

ypdkbd


What are others doing to repair and possible prevent a recurrence?
 
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Weld a small gusset

I've seen a repair made by welding a small 4130 stel gusset in place on the underside.

To prevent future cracking, make sure that no one exits your plane face first. Always back down off of the wing backwards like you are going down a ladder. By going off foreward, the impact load on the step is very high.

Bruce Reynolds
RV-6A
 
I had a similar crack in my cherokee's step, at the joint where the streamline tube was welded to the mounting bracket. I took it off and welded it up on both sides and repainted, and it's doing great now.
 
tmbg said:
I had a similar crack in my cherokee's step, at the joint where the streamline tube was welded to the mounting bracket. I took it off and welded it up on both sides and repainted, and it's doing great now.
Click to expand...

ditto on an arrow -- repair was made >10 yrs ago. still fine.
 
Strange!

What causes the crack? By stepping on the step (even with greater force, stepping off the wing forward), you are applying force dawn- and inward, why would it crack on the inside? Is this not a vibration thing?
 
A possible cause could be that some builders take a hammer to the bottom rear flange pounding it in (away from the underside leg towards the fuselage) in an attemp to make the flange conform better to the curvature of the fuselage in that area. This would definitely put stress on the weld on the bottom side of the leg where most of these cracks appear. I'm curious how many builders have pounded on their flange to make it fit the fuselage a bit better.
 
I don't recall what I did but I think I just cut off a part instead of pounding the metal to fit the fuselage. You can see that in the picture.
 
No pounding allowed?

:eek: Auch!........ I did pound at it a lot with a (rubber) hamer, to make it fit to the fuselage, as flush as possible. No cracks visible yet though! :) (not flying yet!)

Hey man, this is steel! It will not crack that easily, not when beating it with a (rubber) hammer.

But, who knows, you may be right, w'll see when time comes.
 
Step repair made

The first picture shows the weld on the crack itself and then a steel piece was added over the area (inboard portion of step). Also seen out of focus is my pup (white on snow).

StepRepairInner.jpg


The next picture shows the added reinforcement added to the outboard upper portion of the step:

StepRepairOuter.jpg


The step has been primered and should be painted and installed in a few days.
 
If you're going to try and make the flange match up to the fuselage, heat it before you beat it, otherwise you're adding a lot of residual stress to a part that takes high loads. See Bruce Reynolds post for proper use.
Terry
 
Step has been repaired and reinstalled

I painted it last weekend and Monday night Stewart helped me rivet it back on. Now I can put all the panels/flooring back on from this repair and condition inspection squawk fixes and be in flying condition today or tomorrow.
 
Hey--just fill with a little bondo into the crack and then paint over. Test with heavy mother-in-law on next flight.
 
Yep...the step on my -8A cracked too, just like yours. Had a tig welder come and weld it in place. Did a nice job.
 
Step Repair

Jim Wright said:
Yep...the step on my -8A cracked too, just like yours. Had a tig welder come and weld it in place. Did a nice job.
Click to expand...

Jim, more details please. What precautions if any, did you take for the welding in place. I've checked locally and the only welder I know at work won't do it on the plane.
 
I have a crack on the right step of my 6A also and have been watching it for years. Can't find anyone to weld it on the plane. They said the heat would damage the paint.
 
My 2 cents

I thought I would add my experience to the fray. My pac side step broke also, right up next to the weld. I removed the step (ground off a lot of rivets in the baggage floor) I had a local welder fab a steel plug to insert into the tube before welding, then anealed the area. After painting, I was wondering how I was going to rivet in back on. Instead, I painted the heads of some #8 screws, enlarged the holes in the step and fuse and installed with a washer and nut on the inside. It looks great.
 
IMHO these steps should be annealed before being attached to the plane. It certainly would not hurt anything. I, and so does a mechanical engineer / master welder / EAA Tech Counselor, and OSH Welding Instructor think these cracks are being caused by "Heat Affected Zone" because these parts are not annealed after welding. Flexing this "HAZ" area (area where the heat hardened due to welding heat and soft "normal" area) starts the crack from stress rizers. The crack then propigates based on the load.


JMHO.
 
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steps

Not annealing-normalizing, which is the original state of the 4130, unless someone got a bad batch. Attempting to normalize with a torch is a waste of time. The only proper way to do it is a heat treat oven.
The definitive article on this subject was written many years ago by Ron Alexander in Sport Aviation. There is also a Sport Avaition article about Pitts. Pitts does not pre or post heat treat any of their welded structure on the Pitts/ Eagle/Husky aircraft.
My personal experience is that most problems with TIG weld failures are caused by heating the metal too fast and/or not cooling it slowly enough.
I can produce two sample tig welds that look identical. One will fail with one shot from a hammer, the other will not break.
 
jrs14855 said:
Not annealing-normalizing............
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While I agree normalizing would be prefered, normalizing is a form of annealing. Please read the thread I linked to in post #12.


Moving on............ Would you agree this "heat treatment process" would help reduce cracks in the steps of RV's if the metal is heated too fast?
 
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Moving on............ Would you agree this "heat treatment process" would help reduce cracks in the steps of RV's?

No, but specking heaver material would help, on the other hand it is an airplane and will have to be lifted, or adding a strap on the compression side.


if the metal is heated too fast?

It's not!
 
jrs14855 said:
Not annealing-normalizing, which is the original state of the 4130, unless someone got a bad batch. Attempting to normalize with a torch is a waste of time. The only proper way to do it is a heat treat oven.
The definitive article on this subject was written many years ago by Ron Alexander in Sport Aviation. There is also a Sport Avaition article about Pitts. Pitts does not pre or post heat treat any of their welded structure on the Pitts/ Eagle/Husky aircraft.
My personal experience is that most problems with TIG weld failures are caused by heating the metal too fast and/or not cooling it slowly enough.
I can produce two sample tig welds that look identical. One will fail with one shot from a hammer, the other will not break.
Click to expand...

Russ McCutcheon said:
Moving on............ Would you agree this "heat treatment process" would help reduce cracks in the steps of RV's?

No, but specking heaver material would help, on the other hand it is an airplane and will have to be lifted, or adding a strap on the compression side.


if the metal is heated too fast?

It's not!
Click to expand...

So you are disagreeing with jrs14855?

If the step is cracking in what has been categorized by EAA Tech experts as HAV (Heat Affect Zone) it is your contention that "normalizing" the part would not have any effect? Can you state why this would be?
 
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I ordered steps and will not be using them (taildragger + steps doesn't make sense)

let me know if you're interested
 
bkthomps said:
I ordered steps and will not be using them (taildragger + steps doesn't make sense)

let me know if you're interested
Click to expand...

I flew my RV-6 for many years with no steps and I still don't personally need one. However, a few years ago it became obvious that one of my passengers was struggling with getting up on and down off the wing. So I ordered a right-side step.

And it was definitely too long to look right. I first checked with Vans' step vendor to see if they would be interested in producing a shorter step for taildraggers but I never received a positive answer. I sectioned three inches out of my step, put a length of 4130 tubing inside the splice and welded it back together. This made a perfect taildragger step which is located 1/2 way between the wing and the ground.

It looks well-proportioned on the RV-6 and more important my passenger likes it. :)
 
Hi Sam

I?ve been the vender since 2001 and worked for the original vender since 1991, no one has ever asked me about such a step being built for an RV-6, well not that me 42 year old brain can remember.

There would be no point in offering something like this off the shelf, too little demand, however if any one wants one call me and I can probably set it up to be purchased thru Van?s, if you already have one you want shortened I will be happy to do that for you.
 
Russ McCutcheon said:
Hi Sam

I?ve been the vender since 2001 and worked for the original vender since 1991, no one has ever asked me about such a step being built for an RV-6, well not that me 42 year old brain can remember.

There would be no point in offering something like this off the shelf, too little demand, however if any one wants one call me and I can probably set it up to be purchased thru Van?s, if you already have one you want shortened I will be happy to do that for you.
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Hi Russ,

I suggested to Vans that they stock a couple sets if it was easy for the vendor to jig a short step. That's when they suggested I call their vendor.

I got your (I guess it was yours...) phone number from Vans when I inquired about a taildragger step, called the number and talked to someone who said someone would call back but I never received a followup call. Maybe it was just a communication glitch. In any case it wasn't a problem since I went ahead and modified my step.

As RVer's accumulate more mileage (pilots, not planes) a taildragger step might be desirable for some pilots. Mine turned out quite nicely.
 
My apologies for missing your call, these days my only advertised number is to a phone that is in my pocket so that won?t happen again.
 
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