What was found
ALL RIVETS SECURING MASS BALANCE ARM (INSTALLED PER VIKING AIR LTD. ANTIFLUTTER MOD KIT NO VALTOC1136 AND APPROVED PER STC ST01243NY) SHEARED RESULTING IN SEPARATION OF THE SERVO TAB ACTUATION WITH THE MOVEMENT OF THE ELEVATOR CONTROL. PILOT FELT OSCILLATION IN ELEVATOR CONTROL DURING HIGH POWER SETTINGS DURING TAKEOFF AND CLIMB. CAUSE MAY BE DUE TO HEAVY ARM ASSEMBLY ATTACHED WITH ALUMINUM RIVETS TO SERVO TAB END BLOCK AND VIBRATION BETWEEN TAB AND MASS BALANCE ARM ASSEMBLY. TAB P/N: C3TE13-12 MASS BALANCE P/N: VALTOC1136-12 TAB FILLER BLOCK P/N: VALTOC1136-18.