As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING TAKEOFF LEFT ENGINE FAN VIBRATION LEVEL INDICATED IN THE CAUTION RANGE. THE CREW FOLLOWED THE QRH AND RETURNED TO DAY. MAINTENANCE LUBRICATED THE LT ENGINE FAN BLADE TANGS IAW CRJ700 AMM 72-21-02-640-801-A01. ENGINE OPERATIONAL AND VIBE CHECKS WERE GOOD. THE AIRCRAFT WAS THEN RELEASED FOR SERVICE.