What was found
AIRCRAFT WAS GROUNDED: LIGHT TO MODERATE INTERMITTENT AIRFRAME VIBRATION WAS FELT CLIMBING THROUGH 10,000' TO FL250. AUTOPILOT WAS ENGAGED, AIRSPEED WAS INCREASING TO 310 KNOTS, NO FLIGHT CONTROL OSCILLATIONS WERE OBSERVED ON THE F/CTL SD PAGE, VIBRATION WAS FELT ON THE FLIGHT DECK AND MORE PRONOUNCED IN THE MID AND AFT CABIN FLOORS REPORTED BY THE FA'S. CHANGING PITCH AND OR AIRSPEED RESULTED IN NO CHANGE TO THE VIBRATION, AFTER CLIMBING THROUGH FL 250 THE VIBRATION DISSIPATED. (OPEN)