As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
UNUSUAL VIBRATION FELT IN FLOOR OF AC DURING FLIGHT, STRONGEST VIBRATION IN OVERWING AREA AT CABIN. ALSO, A SUBTLE YAWING MOTION FELT IN REAR GALLEY AREA EVERY FEW SECONDS. PRECAUTIONARY EMERGENCY DECLARED & AC DIVERTED. REF LP 6428995, DURING CONDITIONAL INSPECTION FOUND RT ELEVATOR TAB CONTROL VALVE FAILED IN FLAP DOWN POSITION. REMOVED & REPLACED OER 27-31-35-000-801. OPS GOOD.