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  #1  
Old 06-05-2014, 11:47 PM
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RVG8tor RVG8tor is offline
 
Join Date: Mar 2007
Location: McKinney, TX
Posts: 1,261
Unhappy My step cracked.

I was under the plane doing some work and happened to creep by the step and thought that seems to have more movement than I remembered.

Sure enough the back side right at the weld and gusset is a crack, just logged 216 hours. Step stool used when in the hangar so it is only used when getting in and out for flight. I always step back onto the step and have my passangers do the same.

This well be kind of a big job as I cut my flap fairing to just fit the step, the flap fairing will have to come off or at least part of it. then all those rivets to remove, I know a good welder and will ask if this is something that can be done with the stop on the plane.

I wonder if a wad of JB Weld would hold things for a few months, I really don't want the airplane down for the summer flying season.

Cheers

These are photos of the crack and step and fairing.







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  #2  
Old 06-06-2014, 01:04 AM
Steve Barnes Steve Barnes is offline
 
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Location: Santa Rosa, CA
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Default A gusset?

Looks like the added gusset created a stress point and didn't allow the tube to bend naturally.

Steve
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  #3  
Old 06-06-2014, 06:00 AM
novipilot novipilot is offline
 
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Location: Novi, MI & Venice, FL
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Default

I took a continuing education course titled "Fatigue of Weldments". One thing the professor said that has always stayed in my mind is that weldments are instruments of the devil. I know many who have had similar failures. It can't be repaired as all you'll be doing is chasing the crack to some other location near the affected area. We need to design a step that does not have welds, at least in the portion where the step attaches to the tube.
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  #4  
Old 06-06-2014, 07:26 AM
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rocketbob rocketbob is offline
 
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Default

It is mind-boggling that step cracks continue to be a problem that the factory never has had an interest in addressing. "When in doubt build it stout". Doubling the thickness of the steel parts in the steps 2x would solve the problem. Who cares if it gains two pounds in weight.
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  #5  
Old 06-06-2014, 08:56 AM
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akarmy akarmy is offline
 
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Default

Hi Mike. Kind of a bummer I know. I had the same thing happen to my 9A at about the same time. I watched it carefully and in my case it never extended much further than what you show. When I sold it at 700 hours it was still holding and I never dealt with it.

Your JBWeld idea should keep it from flexing if you grind down the outside, but won't really "repair" it. Only true solution is to remove for repair long term.
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  #6  
Old 06-06-2014, 09:23 AM
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RVG8tor RVG8tor is offline
 
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Default Interesting

Quote:
Originally Posted by akarmy View Post
Hi Mike. Kind of a bummer I know. I had the same thing happen to my 9A at about the same time. I watched it carefully and in my case it never extended much further than what you show. When I sold it at 700 hours it was still holding and I never dealt with it.

Your JBWeld idea should keep it from flexing if you grind down the outside, but won't really "repair" it. Only true solution is to remove for repair long term.

Andy,

Funny you should say that, I wondered if the crack is done moving and if it has been there a long time. I say this because the good side now kind of acts like a hinge, when weight is on the step it compresses but when off it just relaxes.

My plan is to baby it until winter when I can tackle the real issue, I might just try a new design I was thinking about when building. I was thinking of a telescoping tube system that would stow flush to the fuselage. This would give me a step that will not crack and less drag!

Cheers
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  #7  
Old 06-06-2014, 09:34 AM
Paul K Paul K is offline
 
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Location: Grand Rapids, MI
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Default

Quote:
Originally Posted by RVG8tor View Post
Andy,

Funny you should say that, I wondered if the crack is done moving and if it has been there a long time. I say this because the good side now kind of acts like a hinge, when weight is on the step it compresses but when off it just relaxes.

My plan is to baby it until winter when I can tackle the real issue, I might just try a new design I was thinking about when building. I was thinking of a telescoping tube system that would stow flush to the fuselage. This would give me a step that will not crack and less drag!

Cheers
Would love to see a design for a telescoping tube step! Might just have to put some time into this and make a project out of it! Anyone? Alan?
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  #8  
Old 06-06-2014, 09:42 AM
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flyboy1963 flyboy1963 is offline
 
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Location: Lake Country, B.C. Canada
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Default ....better than steel?

Quote:
Originally Posted by rocketbob View Post
It is mind-boggling that step cracks continue to be a problem that the factory never has had an interest in addressing. "When in doubt build it stout". Doubling the thickness of the steel parts in the steps 2x would solve the problem. Who cares if it gains two pounds in weight.
If the steel is such a problem, why not an aluminum, or ( gasp!) carbon fibre step? surely one of the keen vendors on VAF could come up with a part that is actually stronger, lighter, and faster than they were before!
(...cue 6 million dollar man musical interlude here...)
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  #9  
Old 06-06-2014, 09:52 AM
David Paule David Paule is offline
 
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Location: Boulder, CO
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JB Weld is a poor idea. It can't pick up enough load to do any good since its modulus of elasticity is no more than 1/40 of the steel. All it will do is hide the crack.

Dave
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  #10  
Old 06-06-2014, 09:55 AM
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Sam Buchanan Sam Buchanan is offline
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Location: North Alabama
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Default

Quote:
Originally Posted by RVG8tor View Post

My plan is to baby it until winter when I can tackle the real issue, I might just try a new design I was thinking about when building. I was thinking of a telescoping tube system that would stow flush to the fuselage. This would give me a step that will not crack and less drag!

Cheers
This has been done. A builder in Tennessee has a RV-6A he built several years ago with retractable steps. They are linked to the canopy with cables so they extend when the canopy is opened. One of the cleverest mods I've ever seen...and I have no idea how he did it.
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