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WD 406 Flap Control weld failure

Hi All,

A question about a weld failure:

I don't think the manual flap control Weldment assembly WD 406 is exclusive to the RV 4. Could be wrong about that but pretty sure the manual flap control in other models would be similar.

We experienced a weld failure at the WD406C which is the horn on the WD406 assembly used to attach the flap lever F446
(RV 4 drawing 37)

The first time this failed I had it re-welded. But now that we've had the same failure twice I am replacing the whole WD 406 assembly.
(Don't want to risk a second repair changing the metallurgy of the torque tube at that point.)

Just wondering if this failure is a one off, or if others have experienced the same thing. If the latter, should I advise Vans of the failure?

Fortunately Vans has a replacement unit in stock and we won't lose too much of this beautiful fall flying weather.
 
RV-4 Flap Weldment

I have close to 1300 hrs on my airframe and am on my 3rd flap crosstube because of handle bracket weldment failure. The first one tore half way around the cross tube when it failed.
The second one I tried reinforcing at the point where the original failed but eventually at about 400 hrs it started to crack.
I Now have a couple hundred hours on the third crosstube and so far so good. Also I now use 90mph as a maximum first notch deployment and 80mph as a maximum second notch deployment. The slower deployment speeds help to reduce any twisting motion introduced between the handle and crosstube while deploying. That and inspect the weldment for any sign of a crack before every flight.
 
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