What was found
AIRCRAFT WAS NOT GROUNDED: APPROX ZERO INTO FLIGHT FO/'S SCREENS STARTED BLINKING OFF THENBACK ON. AT APPROX 3 HOURS AND BEFORE ENTERING OCEANIC AIRSPACESTATUS MDG AHRU R APPEARED. NEXT ''EFIS/DSP PANELR'' CHECK LISTSPEARED AS WELL AS '' EFIS/DSP PANEL R THEN '' WEATHER RADAR SYSL'' MSG APEARED - RAN & COMPELETED CHECK LIST'S. TURNED AIRPLANE AROUND AND RETURNED TO ORD. PFMD PRIMARY DISPLAY SYS OPS TEST AMM 31-61-00. PFMD ISS WXR OPSTEST AMM 34-42-00. PFMD EARTH REF SYS OPS TEST AMM 34-21-00. ALL OPS TESTS PASSED. FAULTS CLEARED.