What was found
LAX - FLT 533 - DURING CLIMB-OUT FROM SNA, THE AIRCRAFT DID NOT RESPOND WELL TO ROLL CONTROL. IT WAS VERY SLOW TO RESPOND TO ROLL INPUT. BETWEEN 0 AND 60 YOKE DEFLECTION THERE WAS A CONSIDERABLE DEAD SPOT NOTED. AS AIRSPEED INCREASED THE ROLL RATE IMPROVED BUT WAS NOT NORMAL UP TO 280 KTS AND MACH .74 AT 28,000 FEET. FLIGHT WAS DIVERTED TO LAX AND ROLL CONTROL WAS VERY LIMITED DURING LANDING. INSPECTED SPOILER AND AILERON SYSTEMS AND CHECKED OPERATION OF SAME. NO FAULTS WERE FOUND. REPLACED 'A' AND 'B' SYSTEM AILERON POWER CONTROL UNITS AS A PRECAUTIONARY MEASURE. ACCOMPLISHED FULL FLIGHT CONTROL CHECK ON TEST FLIGHT AND SYSTEM OPERATED NORMALLY. REFERENCE ASAA954002.