As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
PIT - FLT 864 - AFTER TAKEOFF FROM PIT, A 'FLAP ASYMMETRY' WARNING ILLUMINATED. CREW PERFORMED THE ABNORMAL PROCEDURE CHECKLIST. THE FLIGHT RETURNED TO PIT AND LANDED WITHOUT FURTHER INCIDENT. MAINTENANCE REPLACED THE NR 3 RIGHT SIDE FLAP SYNCHRONIZER. (X)