As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
(CAN) AFTER TAKEOFF, THE AIR GROUND WARNING LIGHT CAME ON AND THE GEAR COULD NOT BE RETRACTED. THE AIRCRAFT RETURNED FOR LANDING. MAINTENANCE FOUND THE SHOCK STRUT WOULD NOT FULLY EXTEND. THE PROBLEM WAS TRACED TO A BRASS RING (NO PART NUMBER) IN THE STRUT ASSEMBLY THAT WAS DEFORMED, CAUSING THE STRUT TO JAM IN THE GROUND (LOADED) POSITION.