Cracking on steps

[BillL]

Originally Posted by grayforge

Bill, what did you do to ensure your steps won't fail?

Thanks,
Russ

I am building a taildragger. I am sure that the A model steps could use a reinforcement like Vans and never fail.

I have been listening to a lot of talk about these steps for years and when I got the chance for a tour, I took the photo. Apparently they don't break now. Good luck in your reinforcement project.

[NYTOM]

Originally Posted by BillL

I am building a taildragger. I am sure that the A model steps could use a reinforcement like Vans and never fail.

I have been listening to a lot of talk about these steps for years and when I got the chance for a tour, I took the photo. Apparently they don't break now. Good luck in your reinforcement project.

Bill I just found you post. Do you notice if the Vans repair had a second gusset on the front of the step also or just the one on the back side in the photo?

[BillL]

Originally Posted by NYTOM

Bill I just found you post. Do you notice if the Vans repair had a second gusset on the front of the step also or just the one on the back side in the photo?

I took this with my iPhone and the lighting was bad to get from the other direction, notice I used my had to ensure even contrast. Yes, the leading and trailing edge seemed to be blended back to the plate the same I don't know what they had on inside.

We had Sterling as the tour host. He answered every question we had with candor. I bet if you called him he could tell you, or would find out, if they did something on the inside (of the fuse) as well to reinforce that step. They have a TIG welding operation there on site for some of their weldments so I bet they did the welding there at the factory. Please post your findings as it has been painful watching all this talk for so long without a solution. I just hate to see such a simple thing not fixed.

[NYTOM]

Thanks Bill, I will post any info I get. I want to be proactive on this continuing problem. Can't imagine finding a crack on a freshly painted plane then having to repair weld in place or have to drill out all those rivets.
Hoping maybe the gussets along with the damping sand will alleviate the problem for good.

[Bikeman55]

Talked to Van's. They have no issue with installing inspection covers. Just said to install nutplates to attach the cover.

[NM Doug]

We discovered a crack yesterday in our adopted 9A's right step (about 350 hours on the airframe) - it was fine when getting into the airplane and wobbly when getting out after the flight.

Given the photos, thoughts on which of the following to do?

1. find someone to do a repair in place and then add sand a la Allan

2. remove, weld a repair, add sand, and reinstall

3. remove and replace with a new step, adding sand before install (looking at an earlier post, it looks like the step mounting flange doesn't come drilled. Besides drilling, would I have to shape the flange somehow?)

Another question - have any of these cracked steps fallen off in flight? We're planning a trip this coming weekend, and we won't be able to get much done before then. We'd plan not to use the step for the time being and just monitor the crack...and then it's condition inspection time in a couple weeks.

- Doug

[Taildrgr]

Looks like it is cracked almost all the way around.
I would try to break it off completely and put a small stepstool in the baggage compartment until you have time to do a proper fix.

[ClayR_9A]

My 10-year-old 9A developed a crack in the right step about a year or two ago. I've just been keeping an eye on it. I rarely fly with a passenger, and don't think this could have been caused by anything except vibration.

Last weekend, I drilled a hole on the inner side about 8" up and put in a good handful of lead shot.

The difference is amazing. Before, when you "thumped" the step, it sounded like plucking a bass guitar string. Now, nothing. No vibration at all.

I went flying and a strange rattling sound I'd been trying to locate for the last year was gone as well. I'm assuming now it must have been the step vibrating.

I'm going to "drill and fill" the left side too. Hopefully it will never fail.

I'd consider this a mandatory fix for all new construction. Maybe using an epoxy slurry of shot to keep everything in place would be a good idea too.

[David Paule]

I'm pretty sure that the cracks are starting at that weld on the inside of the strut. That's a stiff spot. When the step is being used, the strut flexes inward there due to the bending moment. The section of strut shown above the finger here is much more flexible in bending than at the weld.



Since the strut as a whole is flexing inward, and the welded part resists that, the wall of the tube is highly stressed in local bending. That's what's causing the cracking. The stiff area is shown in this photo, and the flexing is in the skin immediately adjacent to the weld, as the strut bends inward:



While there are certainly several ways to solve this problem, my Cessna 180 suggests one approach. If the strut came out of the bottom of the fuselage instead of the side, the attachment fitting could be welded more across the cross-section. That would eliminate the local bending of the strut tube wall, as shown in the next photo where the attachment plate shown doesn't allow the sort of local bending that's causing this issue here.



For this one, the strut continues into the fuselage and is tied to other structure at the floor.

Caveat - I haven't analyzed or modeled the RV step that's cracking. I don't have one available.

Dave

[NM Doug]

I've had a couple other folks agree with Taildrgr's recommendation to break off the step until a good fix or replacement can be made. One very good additional suggestion was to take several photos before breaking it off so that the welder understands the geometry (assuming we try to go the repair route, rather than the replace route).

But I'll take a night cooling off period before committing to this course of action...

- Doug