What was found
VTK FLAG ON CAPTAIN'S SIDE. FOLLOWED QRH PROCEDURE AND WAS ABLE TO RE-ESTABLISH NORMAL OPS. AFTER LANDING, ON TAXI IN, WE HAD A DUAL FAILURE WITH UTK ON BOTH SIDES. ACFT GROUNDED. CDS DEU 1 BITE SHOWS INFLIGHT FAULT 31-67400, NO FMC -1 DATA. RT FMC RESTORED USING FMC RESET PROCEDURE, REF FIM TASK 34-61-836. NORMAL OPS RESTORED AND OPS TEST OK, REF AMM 34-61-00-710-801. VERIFIED SOFTWARE, PN OPS SOFTWARE AND ADJUSTED PERFORMANCE FACTORS, REF AMM 34-61-00-800-801. NAV DATA TRANSFERRED FROM RT FMC CROSSLOAD & UP TO DATE. ETOPS GROUND VERIFICATION COMPLETE.