What was found
AUTOPILOT FAILED AT CRUISE FOLLOWED BY PRIMARY PITCH TRIM FAIL, MACH TRIM FAIL, DURING DESCENT AC BUSS TIE C/B POPPED. AMMETERS INDICATED 50 AMP DIFFERENCE. DURING TROUBLESHOOTING OF THE AUTOPILOT, PITCH TRIM, MACH TRIM & AC BUSS SYSTEMS FOUND CONNECTOR P213 FOR AC PARALLELING BOX TO NOT BE FULLY SECURED. RESECURED P213 AND PERFORMED NUMEROUS OPS CHECKS OF AUTOPILOT, PITCH TRIM, MACH TRIM & AC SYSTEMS WITH NO DEFECTS NOTED AT THIS TIME. IAW AMM CH 22-10, 27-41, AND 24-20. PERFORMED ADJUSTMENT TO THE RT VOLTAGE REGULATOR FOR THE RT GEN AMP SPLIT IS WITHIN LIMITS DURING ALL VARIOUS LOADS IAW AMM 24-31-03.