What was found
DURING FLIGHT AT FL290, AP HOLDING ND, CAUTION ANNUNCIATOR ILLUMINATED. UNABLE TO TRIM THE ACFT DUE TO FROZEN TRIM WHEEL. ONCE BELOW 11,000 FT TRIM WHEEL AND AUTOPILOT BEGAN WORKING NORMAL. LANDING WAS UNEVENTFUL. MAINTENANCE REPLACED BOTH ELEVATOR TRIM ACTUATORS AND PERFORMED RIGGING. ACTUATORS WERE SHIPPED TO MFG ENGINEERING FOR EVALUATION. A SUCCESSFUL OPS CHECK FLIGHT WAS PERFORMED. ACFT WAS RETURNED TO SERVICE. RIGHT PN OFF: 130-52052-19, SN OFF: 52278515-002, LT PN OFF: 130-524052-17, SN OFF: 52257816-004.