On 11/7/2021 6:59 AM, victor taylor via KRnet wrote:
In reference to Dr Feng's safety concerns here is a lot to consider. Keep in
mind like Larry said that this is the first known wing failure of a KR in 30
years.
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For investigative purposes we're fortunate that the failed component
landed separate from the crash site. We should be able to separate
component failure from crash damage. Questions I hope will be answered.
Was spar dimensions as per plans? Type of spar web material? % if
glued area contact between web and caps? Was failure in glue joints or
wood failure? type of glue used? Was there any fuselage material from
where the spar enters the fuselage side that was still attached to the
wing that would indicate the fuselage side at the entry point failed?
Were there any excess holes in the spar caps or web? Did the the spar
fail at a drilled hole? Was there any crash damage in the aircraft's
history? Having the original retracts, several large mounting brackets
were attached to the center spar. Did failure occur at a bracket
location / mounting holes? If so, were holes drilled off center in the
caps creating a weak point? Were aerobatics performed regularly in the
aircraft and were they being performed at the time of the crash?
The exact failure location of the spar will probably provide most of the
answers to our concerns and I suspect there was a weak point(s) built in
to the spar or the airplane was simply over-stressed or a combination of
the two.
Larry Flesner
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