As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
FCU DISPLAY MALFUNCTIONING CLIMB-DESCENT. VERTICAL SPEED WINDOW SHOWS ZEROS IN OPEN CLIMB. REPLACED FCU PER MM WITH KNOWN GOOD UNIT FROM ACFT 4019. ACCOMPLISHED OPERATIONAL TEST OF THE AFS PER 22-96-00 AND LAND CAT III CAPABILITY TEST PER MM 22-97-00, OPS CHECKS GOOD, NO FAULTS NOTED.