Cracks in Nose Wheel Support

[Ron Hoey]

Hi all,

 

Recently, when doing an inspection of my VG XL, I discovered cracks in the bracket which supports the steering wheel channel on the nose leg.

 

The cracks were on both sides of the assembly and you will see from the photos, penetrated all three layers.

 

No need to tell you the consequences of a nose wheel failure.

 

Fortunately I was able to get a steering wheel channel, reinforcement, and new nose leg support from AeroKits. The ring mount allowed us (just) enough room to change it over without removing the engine.

 

The replacement is a modification to strengthen the area and hopefully eliminate a repeat of the issue, so it is obviously a problem which has raised its head before.

 

Consequently, I think we would all be wise to include this item in regular inspections.

 

Regards to all,

 

Ron.

 

Attached Files:

 

• a" style="margin: 0px; padding: 10px 10px 0px; overflow: hidden; zoom: 1; border-radius: 5px; background: url("styles/default/xenforo/gradients/category-23px-light.png") 50% 0% repeat-x rgb(238, 241, 244);">
   
   
  
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  Left side view. note cracks in all 3 components.
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  The assembly after removal.
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[pylon500]

Something has gone wrong with your file upload, original too big maybe?

 

 

[planedriver]

File size appears to be small Arthur. Hope this can be fixed, as it could be very important to other Savvy owners and pilots.

 

 

[Kyle Communications]

I made new ones from stainless steel when I built my XL Ron. I was aware of the issue. Talk to reg Brost..ICP has a totally new bracket that is a different design to solve your problem

 

 

[Kyle Communications]

The new ones I made and some pictures are in my thread on this forum. Even after the noseleg broke off the stainless brackets were still perfect

 

 

[Skee]

I suppose this is what you are talking about.

 

 

 

[Kyle Communications]

Yes them there are the ones

 

 

[facthunter]

Get rid of the front wheel and put a smaller one down the back, and move your mains slightly further forward. Problem fixed forever.. Nev

 

 

[mAgNeToDrOp]

Savannah taildragger isn't going to win any beauty contests in my opinion ;)

 

 

[facthunter]

Why are you guys knocking the nosewheels around anyhow? Can't you hold the weight off it? Nev

 

 

[SDQDI]

..............

[Nobody]

I made new ones from stainless steel when I built my XL Ron. I was aware of the issue. Talk to reg Brost..ICP has a totally new bracket that is a different design to solve your problem

I am not sure if the original is aluminium or steel but generally Stainless Steel has a lower fatigue strength than steel. Substituting materials with a higher tensile strength may lead to poorer performance in service if fatigue is an issue.

 

 

[rotax618]

The nosewheel problem is far more pronounced in the XL and S models because ICP in their wisdom decreased the rake or caster of the nosewheel leg by 6deg over the VG to get a sexier more raked windscreen. This decreased castor places a great deal more stress on the leg and its attachment.

 

 

[facthunter]

Mild steel has a good fatigue performance but a low strength. If you can inspect it easily and considering weight (as we all must). I would have thought a heat treated alloy would be the go . Nev

 

 

[pylon500]

Savannah taildragger isn't going to win any beauty contests in my opinion ;)

Somehow I don't think the position of the wheels makes much difference to the appearance of Heinz/Sav/clone/etc....

 

 

[facthunter]

Too late to think of winning a beauty contest. Surely that's not what it's all about anyhow. Beauty is in the eye of the beholder/ Builder.. Nev

 

 

[Geoff13]

Too late to think of winning a beauty contest. Surely that's not what it's all about anyhow. Beauty is in the eye of the beholder/ Builder.. Nev

Beauty is in the eye of the beer holder.

 

 

[facthunter]

I have it on reliable sources that ALL women look pretty through the bottom of a Beer glass.. Nev

 

 

[Ron Hoey]

Yes, this is similar to the modified replacement I got from Reg. I'll see if I can re-post the photos as I think it is important for us to keep an eye on it. Hopefully the strengthener will prevent a re-occurrence, but will keep an eye on mine.

 

 

Yes, that's

 

 

[Ron Hoey]

 

 

 

 

[planedriver]

Now they are great photo's Ron and very informative, providing others take the trouble to check.

 

Thanks for posting them, they might just save someone's bacon. That's partly what this site is about.

 

Well done!

 

 

[Kyle Communications]

I am not sure if the original is aluminium or steel but generally Stainless Steel has a lower fatigue strength than steel. Substituting materials with a higher tensile strength may lead to poorer performance in service if fatigue is an issue.

Well after the noseleg fork was ripped out of the noseleg strut and the front hit the deck the 2 SS brackets I made had no damage and also neither the U channel support were both perfect. The SS brackets I made were 1.6mm stainless and replaced the supplied aluminium brackets in the kit. I never fitted the alu ones from new .

 

 

 

 

 

 

 

 

[bobcharl]

Been following this thread with interest, because it seems that this cracking must be caused by the side extensions off the main stem which accept the steering rods hammering on the lower bracket during taxi-ing. My interest is because in my installation these side extensions actually clear the bracket by a small amount, perhaps .020 thou. This means that any hammering in my case is occurring on the thrust bearing at the top of the stem. Is this likely to cause problems in that region? Any comments would be greatly appreciated.

 

Bob

 

 

[rotax618]

The top X-member that carries the thrust bearing , throttle etc has been known to crack at the ends at the bend up against the firewall caused by rebound shock. Most of the cracking of the lower fitting is caused by the stops on the leg used to limit the vertical movement of the leg when the aircraft is dropped onto the nosewheel.

 

There are consequences when a fitting is strengthened and made more rigid, it simply transfers the stress, the Nomad aircraft tail cracking modifications demonstrated this admirably.

 

Marks modification looks OK and probably should be included in the kit, the stops on the leg are not a good solution, as the leg is weakend at the point of greatest stress by the holes and the bump stop was never designed to take that force.

 

 

[turboplanner]

In looking at Ron Hoey's earlier photos, there is a fundamental engineering issue with the design.

 

To make use of the strength in a channel you set it up to put tension or pull the flanged (otherwise the flanges would buckle)

 

So you don't compromise the flanges by drilling them or otherwise removing material.

 

In this case much of the flange material has been removed, the flanged are in tension and what's left of the flanged is not enough to carry the load.

 

That's the easy part because that is a very busy little area.

 

A couple my thoughts are:

 

* weld a shaped plate to the flanged where material has been removed.

 

Reinforce the channel by a much heavier plate back to back with the channel so the flanged don't have to do any tension work in that area.