What was found
MOMENTARY LOSS OF BOTH FMC'S. LNAV DISENGAGED, VTK ON CAPTAINS DISPLAY, BOTH MCDU'S LOST FMC DATE. CONDITION CORRECTED ITSELF W/IN 20 SECONDS BEFORE QRH COULD BE COMPLETED. LNAV/VNAV REENGAGED, NO FURTHER OCCURRENCES. GROUNDED - YES. ACCOMPLISHED B737-9 IFIM 34-61-00 FOR FAULT 34-69001 LOGGED ON LAST FLT LEG FAULT NOT ACTIVE PER IFIM THIS AN INTERMITTENT FAULT. OPS CKD NML.