DAVENPORT, IA, USA
N4227N
HEAL SONERAI-I
THE PLT WAS PARTICIPATING IN A PYLON AIR RACE FOR FORMULA V RACERS. ABT HALF WAY THRU THE RACE, AS HE WAS MNVRG PAST THE #2 PYLON, THE LEFT WING BGN TO SEPARATE. THE WING THEN FOLDED OVR THE TOP OF THE ACFT. THE WING & PIECES OF THE CANOPY FELL TO THE GND. AS THE WING SEPD, THE ACFT BGN A VIOLENT ROLL & FLWD A TRAJECTORY PATH TO THE GND. INV REVEALED THE INNER PORTION OF EACH WING WAS DESIGNED WITH BOX SPAR CONSTRUCTION, SECURED TO A FUSELAGE CARRY-THRU CONFIGURATION. THE OUTER WING SPARS CONSISTED OF A SERIES OF UPPER & LOWER STRAPS. THESE WERE SECURED TO A SHEET METAL WEB WITH RIVETS. THE 4 LOWER SPAR STRAPS HAD FAILED; 2 HAD FAILED AT THE 1ST RIVET HOLE OUTBOARD OF THE BOX SPAR CONFIGURATION; ONE FAILED AT THE 1ST BOLT HOLE NEAR THE OUTBOARD END OF THE BOX SPAR & THE 4TH FAILED FLUSH WITH THE OUTBOARD END OF THE BOX SPAR.
FAILURE OF THE WING SPAR STRAPS, AS THE AIRCRAFT WAS BEING MANEUVERED AROUND A PYLON IN AN AIR RACE.
Source: NTSB Aviation Accident Database
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