NTSB Identification: CHI95FA191.
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Accident occurred Tuesday, June 20, 1995 in FRANKFORT, IL
Probable Cause Approval Date: 05/30/1996
Aircraft: Champion 8KCAB, registration: N109AC
Injuries: 1 Fatal,1 Serious.
NTSB investigators either traveled in support of this investigation or conducted a significant amount of investigative work without any travel, and used data obtained from various sources to prepare this aircraft accident report.
THE PRIVATE PILOT-OWNER WAS GIVING AEROBATIC INSTRUCTION TO ANOTHER PRIVATE PILOT. THE PILOT HAD THE SECOND PILOT PLACE THE AIRPLANE INTO INVERTED FLIGHT SO HE COULD SEE WHERE THE NOSE OF THE AIRPLANE SHOULD BE DURING AN AILERON ROLL. THE SECOND PILOT WAS FLYING THE AIRPLANE IN AN INVERTED ATTITUDE WITH FULL POWER AND HIGH RPM. HE TOLD THE SECOND PILOT TO ROLL OUT OF THE INVERTED FLIGHT. THE SECOND PILOT PULLED AFT ON THE CONTROL STICK AND DID A SPLIT-S MANEUVER. THE AIRSPEED WAS ABOVE THE NEVER EXCEED SPEED DURING ITS DESCENT. HE KNEW THIS BECAUSE HE HAD FLOWN ABOVE THAT SPEED BEFORE SO THAT HE COULD KNOW WHAT IT SOUNDED LIKE. AS HE BEGAN TO START RECOVERY THE RIGHT WING SEPARATED, AND WAS THE FIRST AIRFRAME COMPONENT ALONG THE WRECKAGE TRAIL. THE LEFT WING WAS THE SECOND ITEM ALONG THE WRECKAGE TRAIL, AND WAS MANGLED AND TWISTED. THE LEFT WING'S MAIN WING STRUT ATTACH FITTING HAD A FATIGUE STRIATION PATTERN THROUGH ABOUT 90% OF ITS AFT LEG. FATIGUE CRACKING WENT THROUGH ABOUT 25 PERCENT OF THE FITTING'S FORWARD LEG.
The National Transportation Safety Board determines the probable cause(s) of this accident to be: the pilot-in-command's overconfidence in his personal ability in attempting to teach aerobatics, his lack of experience as a flight instructor, and allowing the airplane to get into a position where its never exceed speed and design stress limits were exceeded. The second pilot's improper maneuver was a factor. Full narrative available
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