What was found
WINDSOR LOCKS, CN - DURING CLIMB, HEARD BANG AND AIRCRAFT YAWED LEFT. DUMPED FUEL TO LANDING WEIGHT. RETURNED TO AIRPORT AND LANDED WITHOUT INCIDENT. INSPECTION OF AIRCRAFT REVEALED NO DAMAGE. AFTER SHUT DOWN, NOTED LT CASCADE DOORS ON NR 1 ENGINE OPEN. RAN ENGINE AND OPS CHECKED OKAY. DEACTIVATED THRUST REVERSER AS PRECAUTION PER MEL 78-5. AIRCRAFT RETURNED TO SERVICE. TOTAL CYCLES, 22,038.