What was found
DURING CLIMBOUT, RECEIVED A PRI STAB TRIM FAIL CAS MESSAGE. TRIM SWITCH ON PILOT'S YOKE WOULD NOT ACTUATE TRIM. AFTER APPROX 10 SECS, STAB TRIM STARTED OPERATING NORMAL, BUT WITHIN 20 SECS, KICKED OFF & AGAIN RECEIVED THE PRI STAB TRIM FAIL CAS MESSAGE. CYCLE OCCURRED 3 TIMES. RETURNED TO AIRFIELD. POWERED ACFT & PERFORMED PILOT & COPILOT DISCONNECT OPS CHECK IAW MM 22-10-50. NO DEFECTS NOTED. OHMED PILOT & COPILOT SWITCHES IAW WDM 27-00-01. NO DEFECTS NOTED. OHMED GROUND LUG TO DISCONNECT SWITCHES. INSPECTED AT CONTROL COLUMN MOUNT TO UNDER COCKPIT FLOOR & TO GROUND LUG IAW WDM 22-10-01. NO DEFECTS NOTED. PERFORMED PILOT & COPILOT DISCONNECT OPS CHECK IAW MM 22-10-50. OPS CHECKED GOOD.