As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
ON CLIMBOUT OF AMS, FLIGHT ATTENDANTS NOTICED FUMES INITIALLY STRONG BUT DID NOT DISSIPATE AFTER 50 MINUTES IN FLIGHT. FLIGHT RETURNED TO AMS AND LANDED WITHOUT INCIDENT. REPLACED ALL THREE COALESCER SOCKS AND PERFORMED BURNOUT PROCEDURE. OPERATIONAL CHECK OK.