As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING ROUTINE FUEL PUMP GARLOC SEAL REPLACEMENT FOR LEAKAGE, THE MECHANIC INSPECTED THE FUEL PUMP DRIVE GEAR AND IT BECAME DECOUPLED FROM THE FUEL PUMP. THIS IS NOT NORMAL FOR THIS MODEL PUMP. THE ACCESSORY DRIVE GEAR IS HOLLOW AND HAD THE FUEL PUMP DRIVE MIGRATED FORWARD AND DECOUPLED FROM THE PUMP, THE FCU WOULD HAVE LOST REFERENCE AND CAUSED AN INFLIGHT SHUTDOWN. INSPECTION OF THE DRIVE GEAR APPEARS THE RETAINER IS DEFORMED AND INEFFECTIVE.