What was found
DURING CLIMB, BETWEEN FL20 AND FL30, THE CAPTAIN REPORTED A MODERATE AIRFRAME VIBRATION. FELT THROUGHOUT CABIN, BUT INTENSITY FELT MORE IN THE AFT CABIN. VIBRATION DECREASED WITH SPEED REDUCTION AND RETURNED ON DESCENT. MAINTENANCE REPLACED LEFT ELEVATOR HINGE FITTINGS NR 1 THRU 6 IAW AMM 27-34-41. AIRCRAFT WAS GROUNDED.