NTSB Identification: FTW96LA286.
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Accident occurred Monday, July 01, 1996 in ALMYRA, AR
Probable Cause Approval Date: 05/23/1997
Aircraft: Air Tractor AT-502, registration: N7314C
Injuries: 1 Serious.
NTSB investigators may not have traveled in support of this investigation and used data provided by various sources to prepare this aircraft accident report.
The pilot stated that during the turn around maneuver, he extended full flaps [26 degrees] and the 'flaps remained fully extended thus jamming [the flight] controls.' Manufacturer personnel stated that 5 to 8 degrees of flaps may be used as a turning aid. Flight control continuity was confirmed. The wing flap actuator components and microswitches were intact, were not deformed, and tested functional as designed. The actuator jackscrew was extended 3 1/2 inches (flaps 26 degrees). Push rod clearance at full flaps and full aileron is a minimum of .257 inch. An actuator jackscrew extension of 4 1/16 inches is required before the actuator assembly malfunctions. An extension beyond 4 inches (flaps 34.5 degrees) places the flap push rod and the aileron push rod in contact; however, the controls continue to be movable. Multiple flap actuator assembly malfunctions are required to jam the flight controls.
The National Transportation Safety Board determines the probable cause(s) of this accident to be: The pilot's failure to maintain aircraft control. A factor was the pilot's excessive use of flaps during the maneuver. Full narrative available
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