As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
ON FLIGHT 3814 (ATL TO IAD) ON TAKEOFF CREW NOTICED THAT THE LEFT ENG FAN VIBE IN YELLOW (1.9) HAD TO KEEP POWER BELOW 76% N1 TO KEEP VIBRATION IN GREEN RANGE. CREW ACCOMPLISHED QRH AND PERFORMED AIR RETURN TO ATL. APPLIED LUBRICATION ON THE FAN BLADE IAW CRJ 90 AMM 72-21-02 SEE ITEM 2 FOR OPERATIONS CHECK AML 2274553.