What was found
DURING CRUISE FLIGHT, AP TRIM IS RWD POSTED ON AND OFF EVERY FEW SECONDS. AUTO-PILOT DISCONNECTED. NOTICED THAT AILERON IS EXTREMELY HARD TO MOVE ALMOST BLOCKED. IN DESCENT WITHOUT AUTO-PILOT, WE NOTICED THAT THE ELEVATOR ALSO COULD NOT BE MOVED (FL310-300 / SAT -50 C). AROUND FL290 AND AFTER APPLYING STRONG INPUT, THE AILERON CAME FREE WITH A JERK. AROUND FL130 (TAT 0C), ELEVATOR FREE AGAIN. APPROACH AND LANDING NORMAL. AILERON AND ELEVATOR SERVO MOUNT CHANGED. OPERATIONAL TESTS ON A/P SERVOS SUCCESSFULLY PERFORMED. AILERON SERVO CYCLE 18126/ HOURS 23075 ELEVATOR SERVO CYCLE 19592/ HOURS 24455.