What happened
The FAA’s narrative, in sentence case. The FAA writes it in capitals and removes private details.
An Air tractor AT802A was involved in a take-off incident, causing substantial damage. The aerial application operator was attempting to take off from an unapproved grass landing strip on a runway heading of 090 degrees with winds that day being 240 degrees at 12 knots, gusting to 20 knots. When the airplane struggled to gain lift, the PIC looked to his left and right and noticed the flaps were retracting uncommanded after selecting 20 degrees for takeoff. At this point, the runway distance was quickly decreasing, and the PIC attempted to abort the takeoff, selecting full reverse thrust; however, it was too late, and the airplane hit a drainage ditch at the end of the runway. In the incident sequence, the engine propeller, left wing, and aerial application apparatus struck the ground/ditch. The left main landing gear was also severed from the airplane. One POB, no injuries.
The investigator in charge (iic) discovered that the flap actuator assembly coupling, part number B100-06, which serves as the connection between the electric flap motor and the actuator lying at the bottom of the aircraft, was broken. Upon examination, it was found that the metal keys within the coupling had sheared off, leading to the failure of this critical component. According to Air tractor service letter (sl) 260, which provides detailed information regarding the flap actuator coupling, the manufacturer recommends replacing the coupling after 400 hours of operation. However, in this instance, the coupling failed at 575.7 hours, significantly exceeding the recommended replacement interval.
As the FAA filed it
AN AIR TRACTOR AT802A WAS INVOLVED IN A TAKE-OFF INCIDENT, CAUSING SUBSTANTIAL DAMAGE. THE AERIAL APPLICATION OPERATOR WAS ATTEMPTING TO TAKE OFF FROM AN UNAPPROVED GRASS LANDING STRIP ON A RUNWAY HEADING OF 090 DEGREES WITH WINDS THAT DAY BEING 240 DEGREES AT 12 KNOTS, GUSTING TO 20 KNOTS. WHEN THE AIRPLANE STRUGGLED TO GAIN LIFT, THE PIC LOOKED TO HIS LEFT AND RIGHT AND NOTICED THE FLAPS WERE RETRACTING UNCOMMANDED AFTER SELECTING 20 DEGREES FOR TAKEOFF. AT THIS POINT, THE RUNWAY DISTANCE WAS QUICKLY DECREASING, AND THE PIC ATTEMPTED TO ABORT THE TAKEOFF, SELECTING FULL REVERSE THRUST; HOWEVER, IT WAS TOO LATE, AND THE AIRPLANE HIT A DRAINAGE DITCH AT THE END OF THE RUNWAY. IN THE INCIDENT SEQUENCE, THE ENGINE PROPELLER, LEFT WING, AND AERIAL APPLICATION APPARATUS STRUCK THE GROUND/DITCH. THE LEFT MAIN LANDING GEAR WAS ALSO SEVERED FROM THE AIRPLANE. ONE POB, NO INJURIES.
THE INVESTIGATOR IN CHARGE (IIC) DISCOVERED THAT THE FLAP ACTUATOR ASSEMBLY COUPLING, PART NUMBER B100-06, WHICH SERVES AS THE CONNECTION BETWEEN THE ELECTRIC FLAP MOTOR AND THE ACTUATOR LYING AT THE BOTTOM OF THE AIRCRAFT, WAS BROKEN. UPON EXAMINATION, IT WAS FOUND THAT THE METAL KEYS WITHIN THE COUPLING HAD SHEARED OFF, LEADING TO THE FAILURE OF THIS CRITICAL COMPONENT. ACCORDING TO AIR TRACTOR SERVICE LETTER (SL) 260, WHICH PROVIDES DETAILED INFORMATION REGARDING THE FLAP ACTUATOR COUPLING, THE MANUFACTURER RECOMMENDS REPLACING THE COUPLING AFTER 400 HOURS OF OPERATION. HOWEVER, IN THIS INSTANCE, THE COUPLING FAILED AT 575.7 HOURS, SIGNIFICANTLY EXCEEDING THE RECOMMENDED REPLACEMENT INTERVAL.