After the airplane’s third touchdown, the data showed three simultaneous events
indicating that the pitch uncoupling mechanism had uncoupled. First, the control column
positions deviated from their normally recorded deviations. Second, the left and right
elevators began to move independently of each other. Last, the FDR pitch uncoupling
parameter showed “warn.” None of these events were present before the third touchdown.
Therefore, the Safety Board concludes that the pitch control uncoupling mechanism
uncoupled when the airplane touched down for the third time; as a result, the pitch
uncoupling would not have prevented the flight crew from controlling or safely landing
the airplane.