As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
FLT 1418 JAX-BOS, CREW DECLARED EMERGENCY DUE TO FCTL FLAPS LOCKED AT SELECTION OF FLAPS 2 AT 185 KNOTS. TROUBLESHOOT FLAP ASYMMETRY PER TSM 27-51-00-810-819-A FOUND LEFT APPU (ASYMMETRY POSITION PICK OFF UNIT) TO BE AT FAULT. REMOVED AND REPLACED APPU PER AMM 27-51-18-00-001-A, OPS TEST GOOD.