As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING CRUISE FLIGHT LEFT CDU BLANKED FOR 10-15 SECONDS. WHEN DISPLAY CAME BACK, BRIEFLY SHOWED DATA AS DURING POWER UP. GROUNDED - YES. PERFORMED FIM 34-6I TASK 801 FMC BITE SHOWS NO FAULTS, LEFT CDU OPERATES AS PER FIM 34-6I TASK 804. AIRCRAFT OK FOR SERVICE.