NTSB Identification: CHI84AA016.
The docket is stored on NTSB microfiche number 22377.
Accident occurred Sunday, October 09, 1983 in BATTLE CREEK, MI
Aircraft: KEMMEYER SONERAI II, registration: N22SK
Injuries: 1 Fatal.

THE PLT FLEW THE HOME BUILT ACFT FROM BATTLE CREEK TO MARSHALL, MI TO TALK TO FRIENDS. AFTER ABOUT 30 MIN, HE TOOK OFF WITHOUT REFUELING. SHORTLY AFTER THE ACFT DEPARTED, A WITNESS ON A GOLF COURSE HEARD THE SOUND OF THE ENG. HE LOOKED UP & SAW THE ACFT IN ABOUT A 30 DEG CLIMB. REPORTEDLY, THE ACFT CLIMBED APRX 400 TO 500 FT, TO A HEIGHT OF ABOUT 2000 TO 3000 FT, THEN THE NOSE CAME DOWN SLOWLY & THE ACFT STARTED DESCENDING. THE WITNESS OBSERVED THE ACFT CONTINUE DESCENDING UNTIL THE PLT STARTED TO PULL OUT OF THE DIVE. DURING THE PULL-OUT, THE RIGHT WING FOLDED UPWARD & SEPARATED. THE ACFT THEN WENT INTO A RAPID SPIN & CRASHED. AN EXAM OF THE WRECKAGE REVEALED THAT THE RIGHT WING HAD SEPARATED AT THE ROOT. THE SEPARATED WING HAD A CREASE STARTING AT THE LEADING EDGE WING ROOT & ANGLED OUTBOARD & REARWARD AT A 45 DEG ANGLE. AN EXAM OF THE TOP SPAR CAP SHOWED EVIDENCE OF BUCKLING PRIOR TO WING SEPARATION.A LOG SHOWED THAT THE PLT HAD PREVIOUSLY PERFORMED AEROBATIC FLT. THE ACFT WAS NOT CERTIFIED FOR AEROBATICS.

The National Transportation Safety Board determines the probable cause(s) of this accident to be:

DESIGN STRESS LIMITS OF AIRCRAFT..EXCEEDED..PILOT IN COMMAND




Contributing Factors

WING,SPAR..OVERLOAD


Contributing Factors

WING,SPAR..BUCKLED

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