What was found
DURING APPROACH, SLAT ASYMMETRY OCCURRED AND AIRCRAFT ROLLED LEFT. SLAT DISAGREEMENT LIGHT ILLUMINATED WITH NO BLUE SLAT EXTEND LIGHT. CAPTAIN DECLARED A YELLOW EMERGENCY AND EMERGENCY EQUIPMENT WAS CALLED OUT AS A PRECAUTION. AIRCRAFT LANDED WITHOUT INCIDENT. OPERATED SLATS, INSPECTED T-DUCTS AND ALL CHECKED OK. DISCREPANCY COULD NOT BE DUPLICATED AND AIRCRAFT RETURNED TO SERVICE.