What was found
CREW REPORTED FMS 1 & 2 UNAVAILABLE ENROUTE, DIVERTED & DECLARED AN EMER. ACFT IS IN WORK. MDC SHOWS FLIGHT MANAGEMENT COMPUTERS 1 & 2 FAILED & IRS 1 & 2 FAILED. CLIMBING THROUGH 27,000 A RE-ROUTE WAS RECEIVED. THE CHANGE WAS PROGRAMMED IN FMS 2. WHILE VERIFYING THE ROUTE ANOTHER CHANGE WAS MADE IN FMS 1. THE FMS THEN NOTED, FMS 1 NOT AVAILABLE. THE CHANGE WAS THEN INITIATED IN FMS 2, ABOUT 2 MINUTES LATER. THEN FMS 2 INDICATED, FMS 2 NOT AVAILABLE. CB`S WERE CHECKED, BUT ALL NORMAL. HEADING, ALTITUDE & SPEED ALL NORMAL AS WELL AS NORMAL AUTO PILOT FUNCTIONS IN HDG MODE. PERFORMED RESET PROCEDURES OF FMS SYS & OPERATIONS TESTED GOOD IAW AMM 34-61-01. NO DEFECTS NOTED. ACFT REMAINS IN CAT II & RVSM OPERATIONS.