What was found
(AIRCRAFT GROUNDED) STRONG AIRFRAME VIBRATION FROM 330 KTS - 260 KTS AT FL250. VIBRATION WAS FROM TAIL OF AIRCRAFT ON UP AND DOWN MOTION. / FOUND L/H ELEVATOR HINGE FITTING BUSHINGS 1-5 OUT OF LIMITS PER AMM 27-34-41-200-001-A, BUSHINGS OR ELEVATOR REQUIRES REPLACEMENT. (W/O: 540163, TASKCARD: NR-00007). INSTALLED L/H ELEVATOR HINGE-ARM END-FITTINGS 1,2,3,5,6 IAW AMM 55-16-42-400-001-A, STEP 4 (W/O: 540163, TASKCARD: NR-00010).REPAIRED HINGE ARM FITTING #4 BONDING STRAP IAW AMM 55-16-42-300-001 TO TO REPAIR PROCEDURE (W/O: 540163, TASKCARD: NR-00009). INSTALLED SHOULDER BUSHING IAW SRM 51-2-12-911-002.