NTSB Identification: LAX89DUQ05.
The docket is stored on NTSB microfiche number 41986.
Accident occurred Saturday, September 02, 1989 in CALIFORNIA CITY, CA
Probable Cause Approval Date: 07/22/1992
Aircraft: RUPPERCHT VARIEZE, registration: N393D
Injuries: 2 Fatal.

THE PIC/OWNER/BUILDER DEPARTED CALIFORNIA CITY, CA, ON A LOCAL PERSONAL FLIGHT. A GND WITNESS REPORTED THE AIRPLANE WAS AT A HIGH ALTITUDE IN LEVEL FLIGHT WHEN SUDDENLY THE WINGS FOLDED. THE AIRPLANE THEN DESCENDED OUT OF CONTROL INTO A LAKE BED. WRECKAGE EXAMINATION DISCLOSED THAT ONE SET OF THE WING ATTACHMENT PLATE TAPER CONES AND THE RETAINING BOLTS WERE MISSING. THE REMAINING TAPER CONES WERE NOT SEATED PROPERLY AND THE RETAINING BOLTS WERE STRETCHED AND NECKED DOWN WHICH ARE CHARTERISTIC OF OVERTORQUING. THE REMAINING BOLTS APPEARED TO HAVE BEEN OVERTORQUED IN ORDER TO SEAT THEIR RESPECTIVE ATTACH CONES.

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

THE WING FAILED DUE TO THE PILOT/OWNERS OVERTORQUING THE WING BOLTS AND THE IMPROPER INSTALLATION OF THE WING ATTACH PLATES/CONES.

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