WETUMPKA, AL, USA
N44GP
PITTS S1-SP
THE ACFT EXPERIENCED AN INFLT STRUCTURAL FAILURE OF ITS UPPER WING DURING AEROBATICS IN AN AIR SHOW. THE ACFT WAS LANDEDSAFELY AND THE PILOT WAS NOT INJURED. THE UPPER WING LEADING EDGE RIBS REPORTEDLY COLLAPSED AS THE PILOT BEGAN TO PULL UP AT THE BEGINNING OF AN EIGHT-SIDED LOOP AT ABOUT 200 KTS. AN FAA OBSERVER REPORTED THAT ABOUT 60% OF THE UPPER WING FABRIC THEN PEELED REARWARD AND SEPARATED. THE PILOT 'ABORTED THE SHOW' AND LANDED WITHOUT FURTHER INCIDENT. EXAMINATION BY AN FAA INSPECTOR AND THE OWNER REVEALED THAT THE LEADING EDGE OF THE UPPER WING HAD COLLAPSED REARWARD TOTHE FRONT SPAR WITH ALL NOSE RIBS BROKEN. THIS ACFT IS ONE OF TWO WITH 'KERMIT WEEKS' WINGS. THE FAILURE DESCRIBED HAS ALSO HAPPENED WITH THE OTHER ACFT. BOTH ACFT UPPER WINGS HAD BEEN CONSTRUCTED OF LIGHTER WEIGHT MATERIALS WITH EMPHASIS ON IMPROVED PERFORMANCE. SUBSEQUENT TO THIS ACCIDENT THE WING WAS REBUILT WITH STRONGER MATERIALS TO WITHSTAND HIGHER LOADS.
Source: NTSB Aviation Accident Database
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