As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
ON FLIGHT 4521, THE CREW REPORTED AN ENGINE 1-2 FUEL IMPENDING BYPASS ON CLIMBOUT. THE CREW DECLARED AN EMERGENCY AND RETURNED. THE AIRCRAFT LANDED WITHOUT INCIDENT. AIRCRAFT REMOVED FROM SERVICE. REMOVED AND REPLACED THE NR 1 AND NR 2 ENGINE FUEL FILTER IAW MM 73-21-10. OPS AND LEAK TESTED GOOD IAW MM 72-00-00. AIRCRAFT RETURNED TO SERVICE.