What was found
PTRIM MNL FAIL YELLOW CAS: SHORTLY AFTER INITIATING DESCENT FROM FL410, WE OBSERVED A PTRIM NML FAIL AMBER CAS. WE COMPLIED WITH QRH. CAS MESSAGE REMAINED ILLUMINATED THROUGH LANDING AND SHUTDOWN. "CORRECTIVE ACTION" FOUND PITCH TRIM BACK UP SWITCH IN BACKUP POSITION CAUSING A HARD FAULT CAS MAESSAGE OF THE PTRIM NML FAIL. TURNED BACK UP SITCH TO THE OFF POSTION , PERFORMED OPERATION CHECK PEER PHHELNOM 300 AMM 27-41-00. OPS CHECKS GOOD