What was found
CREW REPORTED CLIMBING THROUGH FL 220 AT 340 KTS A/C VIBRATION FELT ON THE HORIZONTAL AXIS. MX REPLACED THE RUDDER HINGE ARM FITTINGS: NR 1, NR 2, NR 3, NR 4, NR 5, AND NR 7. OPERATIONAL CHECK WAS GOOD. THE AIRCRAFT WAS RETURNED TO SERVICE.