As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AIR TURNBACK, NLG RED WARNING LIGHT ILLUMINATED AFTER TAKEOFF/GEAR RETRACTION. LOUD NOISE FROM DRAG CONTINUED UNTIL GEAR HANDLE PLACED IN DOWN POSITION. ALL INDICATIONS THEN APPEARED NORMAL. FOUND NLG UPLOCK HYDRAULIC LINE LEAKING. REMOVED AND REPLACED HYDRAULIC LINE AND CYCLED GEAR, OP''S CHECK GOOD PER MM.