As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
(CAN) AFTER TAKEOFF, THE CREW NOTICED THAT THE LEFT MAIN GEAR HAD NOT RETRACTED AND THE CREW RETURNED FOR LANDING. UPON INSPECTION, THE LEFT TORQUE TUBE ASSEMBLY WAS FOUND TO BE CRACKED ALONG ITS LENGTH LIKE AN UNWRAPPED PAPER TOWEL CARDBOARD TUBE. THE CRACK APPEARED TO ORIGINATE FROM THE WELD AROUND THE HOLE FOR THE MAIN LANDING GEAR FORK BOLT.