As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
WHILE PERFORMING T/C NG-28FCD-18088-1, FOUND UNIT F1 TO BE OUT OF TOLERANCE. ACFT GROUNDED. F1 TANK UNIT ON THE NR 1 MAIN FUEL TANK REMOVED AND REPLACED IAW AMM 28-41-21. UNIT WITHIN TOLERANCE NOW. SYSTEM TESTED GOOD IAW AMM 28-41-00-730-801, COMPARISON CHECKED GOOD IAW AMM 28-41-00-720-801.