2 INITIAL FINDINGS
On the basis of the initial information gathered during the course of the investigation, the following facts have been determined:
3
The Aircraft possessed a valid certificate of airworthiness;
The crew obtained the license and qualifications to conduct the flight;
The takeoff roll appeared normal, including normal values of left and right angle-of-attack
(AOA).
Shortly after liftoff, the value of the left angle of attack sensor deviated from the right one
and reached 74.5 degrees while the right angle of attack sensor value was 15.3 degrees;
then after; the stick shaker activated and remained active until near the end of the flight.
After autopilot engagement, there were small amplitude roll oscillations accompanied by lateral acceleration, rudder oscillations and slight heading changes; these oscillations also
continued after the autopilot disengaged.
After the autopilot disengaged, the DFDR recorded an automatic aircraft nose down (AND)
trim command four times without pilot’s input. As a result, three motions of the stabilizer trim were recorded. The FDR data also indicated that the crew utilized the electric manual trim to counter the automatic AND input.
The crew performed runaway stabilizer checklist and put the stab trim cutout switch to cutout position and confirmed that the manual trim operation was not working.