As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
(CAN) DURING THE UNDER FLOOR INSPECTION THE AME NOTICED THE AFT CHAIN FOR THE LANDING GEAR ACTUATION SYSTEM HAD JUMPED ONE SET OF TEETH ON A SPROCKET. FURTHER INVESTIGATION FOUND THAT THE CHAIN TENSION WAS OUT OF TOLERANCE WHICH HAS BEEN DETERMINED TO BE THE CAUSE OF THE CHAIN JUMPING ONE TOOTH. THE CHAIN AND SPROCKET WERE CHANGED. THE CHAIN WAS WITHIN ITS STRETCH LIMITS.