MANSFIELD, WA, USA
N5321U
CUSHING 4
THE LEFT WING OF THE HOMEBUILT SEPARATED IN FLIGHT. THE WING MAIN SPAR WAS A HEAVY WOODEN BEAM WITH METAL REINFORCEMENT PLATES BOLTED TO THE FORE AND AFT SURFACES THAT EXTENDED THROUGH THE AIRCRAFT CABIN. THE SPAR WAS FOUND BROKEN ADJACENT TO THE LEFT SIDE OF THE CABIN, THROUGH BOLT HOLES AT THE METAL REINFORCEMENT BRACKETS. THE WOOD SPLINTERS IN THE FRACTURED SPAR WERE BENT TOWARD THE TOP SURFACE OF THE WING. THERE WAS NO EVIDENCE OF FATIGUE CRACKING OR DRY ROTTING.
FAILURE OF THE LEFT WING MAIN SPAR DUE TO OVERLOAD FOR UNDETERMINED REASONS.
Source: NTSB Aviation Accident Database
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