Crack in step

bpattonsoa · #1 06-05-2011, 04:36 PM

I have a step on the pilots side only on my -6A. The step is cracked across the bottom weld where the airfoil shaped tube meets the steel plate that is rivited to the fues side. The crack is along the full length of the bottom, but has not progressed to the top.

Now I must confess, the crack has been there for about 50 hours. Every time I get out, I look before stepping and I try to put the minimum weight on the step when entering. It does not seem to want to progress (or go away).

I have a new step, but hate the thought of drilling out all those rivets, removing the floorboards and putting the new one on. Plus the plane is painted with Imron, and I have no paint left. The weld is too close to the aluminum to have it TIG welded (I think).

Anyone else see this issue, Vans said they had heard of it, but just recommended putting in a new step. More importantly, any ideas?

Bruce Patton
RV-6A, flying since '99

Ron Lee · #2 06-05-2011, 04:38 PM

You might want to use the search function for

step crack

very common. Happened to me too.

Here was my post:

http://www.vansairforce.com/communit...ght=step+crack

bpattonsoa · #3 06-05-2011, 06:21 PM

Wow, I did a search and find these cracks are not at all unique.

So, I have changed my question to:

With a crack across the bottom, how long can i get away with it before it lands in someone's backyard? (Or I end up on my back)

Bruce Patton

johnfurey · #4 06-05-2011, 06:30 PM

Both the left and right steps cracked on a 6A of mine. Like yours they were on the under side and ran all across and started to show on top. A friend used my TIG welder and in a very short time you would have to look close to see they were welded. It did burn the paint off but on the step only. Paint store matched the paint and put it in an aerosol can and it looks good as new. I would not take a chance dropping it in the wrong place.

gasman · #5 06-06-2011, 03:26 AM

The step will crack just under the weld bead. If you just run another bead over the crack it will crack again just under that bead. Unless you change the way that you use the step.
There are many steps out there that have not cracked...... Ease your weight on the step. Never step (drop your weight) on it. Never turn around on the wing and face back stepping on the step.

A 1 1/2" patch welded over the repaired crack and welded down the underside of the step will help if you are going to abuse the step.

trib · #6 06-06-2011, 09:44 AM

I haven't heard of issues with the step, or that there was a correct way to step on/off of the wing. I can see not stepping hard onto the step, but my normal exit is to step out of the cockpit and step off the wing facing the tail. Much easier to see where I'm going if I'm stepping forward and not backward. Is Gasman's method generally accepted? Of course, the weight of the individual would be a factor, also.

Greg Arehart · #7 06-06-2011, 10:35 AM

If you look at the past posts, the prevailing wisdom is that these steps are not failing because of people stepping on them. That would put the underside of the step in compression and, therefore, not likely to fail in the manner described. So (IMO), putting weight on the steps (even Bubba weight) is not the issue. I don't really think it will matter how one exits the plane using the step in terms of causing this failure mode. More likely (again from the archives) is that there has been stress set up during the welding/building process. This may be exacerbated by some harmonics resulting from propwash.

Simplest solution seems to be welding a reinforcement patch, which can be done while the step is on the plane by a good welder.

My two cents.

greg

Mike S · #8 06-06-2011, 10:39 AM

Quote:

Originally Posted by trib

I haven't heard of issues with the step, or that there was a correct way to step on/off of the wing.

Slowly putting your weight on the step, Putting the weight as close to the elbow joint as you can.

gasman · #9 06-06-2011, 11:32 AM

Quote:

Originally Posted by Greg Arehart

If you look at the past posts, the prevailing wisdom is that these steps are not failing because of people stepping on them. That would put the underside of the step in compression and, therefore, not likely to fail in the manner described. So (IMO), putting weight on the steps (even Bubba weight) is not the issue. I don't really think it will matter how one exits the plane using the step in terms of causing this failure mode. More likely (again from the archives) is that there has been stress set up during the welding/building process. This may be exacerbated by some harmonics resulting from propwash.

Simplest solution seems to be welding a reinforcement patch, which can be done while the step is on the plane by a good welder.

My two cents.

greg

Looking at the top weld you can see that it would have to be stretched apart for it to fail. The under weld of the step leg to the mounting plate ( the arm pit) has a problem if the leg materal is not thick enough for the load applied. As you place your weight on the step, the force that you apply will cause the step to try and rotate down and under the fuselage. The weld bead is like a gusset and the stress and flex happens just below the weld.

So, if you set your foot on the step and then apply your load, the step has a chance. If you drop your weight on the step, the step will see much more than your weight.

AlexPeterson · #10 06-06-2011, 08:34 PM

Quote:

Originally Posted by Greg Arehart

If you look at the past posts, the prevailing wisdom is that these steps are not failing because of people stepping on them. That would put the underside of the step in compression and, therefore, not likely to fail in the manner described. So (IMO), putting weight on the steps (even Bubba weight) is not the issue. I don't really think it will matter how one exits the plane using the step in terms of causing this failure mode. More likely (again from the archives) is that there has been stress set up during the welding/building process. This may be exacerbated by some harmonics resulting from propwash.

Simplest solution seems to be welding a reinforcement patch, which can be done while the step is on the plane by a good welder.

My two cents.

greg

Why wouldn't it fail in compression? Lots of things fail in compression, especially where there is a discontinuity, such as a weld bead. The compression in the lower weld may even be inducing a local tension at the edge of the weld. I'll probably get a chance to look at a cracked one closely, as I'm coming up on 1300 hours on mine.

I would be extremely surprised if it weren't due solely to the forces being put on it by our feet.