Final Weldment update

Just got the lab report on the aircraft and the weldments broke due to stress fractures. I have advised Van's to put a non aerobatic bulletin for all early RV4's until replacement with post 1988 design or complete inspection to include dye penetrant on the existing weldments. Bear in mind this aircraft was never overstressed according to Van's guidelines. Roger Moore

Weldment

Roger,

Which weldment are you talking about? Some of us did not build the airplanes and we need to know which one(s) you are talking about. Help the rest of us out.

Roger Moore said:

Just got the lab report on the aircraft and the weldments broke due to stress fractures. I have advised Van's to put a non aerobatic bulletin for all early RV4's until replacement with post 1988 design or complete inspection to include dye penetrant on the existing weldments. Bear in mind this aircraft was never overstressed according to Van's guidelines. Roger Moore

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Apparently the parts are being over stressed during some operation that is outside the static load test values determined by the designer.

It is possible that landing on a bumpy runway could cause load oscillations that exceed the static load G ratings.
Were the failures fatigue related failures or simple overloads?

Of course all my speculation is just pure cr_p, not knowing which weldment you are even referring to. If they are engine mount weldments, they probably are not subject to the static load proof tests of the airframe and would therefore simply be designed in an analytical manner, missing out on the proof loading.

-mike