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properly made, be the strongest point in a tubular member and loads exceeding design strength of the part should fail it at a point adjacent to the weld rather than through the weld itself.
Conclusions
The Board concludes that the inflight structural failure resulted from the separation of a glued wood joint. The Board further concludes that proper bonding between the wood and glue was not obtained during production because of improper techniques and control. It is also concluded that the design practices did not provide a sufficient margin of safety to guard against weakening of the structure over a prolonged period.
As a result of recommendations made by the Board to the Administrator of the Federal Aviation Agency following this investigation, the latter issued an airworthiness directive to correct these deficiencies. (See Attachment "A".)
Probable Cause
The Board determines that the probable cause of this accident was an inflight structural failure brought about by the separation of an improperly glued wood joint.
BY THE CIVIL AERONAUTICS BOARD:
/s/ WHITNEY GILLILLAND
Chairman
/s/ CHAN GURNEY
Vice Chairman
/s/ G. JOSEPH MINETTI
Member
/s/ ALAN S. BOYD
Member
