What was found
ON ROTATION & CLIMB OUT, PRIMARY PITCH TRIM FAILED. SWITCHED TO SECONDARY WHICH ALSO FAILED. RAN QRH. TECHS REVIEWED TEAM 680'S ARES ANALYSIS, WHICH DETERMINED THE PRI STAB TRIM FAIL EVENT WAS LIKELY CAUSED BY SIMULTANEOUS PITCH TRIM INPUTS FROM BOTH PILOT & COPILOT, RESUITING IN AUTOPILOT CONTROL UNIT ENTERING AN INVALID STATE. IAW TEAM 680'S RECOMMENDATION, TECHS RESET THE ACU WITH ACFT POWER ON & PERFORMED A FULL-TRAVEL OPS CHK OF PITCH TRIM SYS. PRIMARY & SECONDARY PITCH TRIM SYS OPS NORMAL THROUGHOUT FULL RANGE OF TRAVEL WITH NO FAULTS OR ABNORMAL INDICATIONS NOTED. NO TRIM FAIL CAS MESSAGES REOCCURRED DURING OPS TESTING. ALL WORK PERFORMED IAW AMM 27-00-00 FLT CONTROL TROUBLESHOOTING & WDM 27-40-01-02.