What was found
CLIMBING THROUGH 18,000 FEET, AT 280 KNOTS WITH THE NR 1 AUTO PILOT ENGAGED, A DISTINCT & PRONOUNCED BOUNCE & VIBRATION SET UP IN THE LONGITUDINAL AXIS OF THE ACFT. VIBRATION REDUCED WHEN SPEED DECREASED. THE FLIGHT DECLARED AN EMER & DIVERTED WITHOUT FURTHER INCIDENT. THE ACFT WAS GNDED. REPLACED LT & RT HORIZONTAL STABILIZER CTR HINGE FITTING BEARINGS IAW ROUTINE CARDS 27-94-11 12. SEE ALSO SDR AALA 20160525001 & AALA 20160525002.