As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
LOSS OF NOSE WHEEL STEERING ACCOMPANIED BY SMOKE IN CABIN OCCURRED DURING TAXI OUT. RIGHT HYDRAULIC SYSTEM QUANTITY WENT TO ZERO. AIRCRAFT RETURNED TO THE GATE. MAINTENANCE FOUND RUDDER POWER SHUTOFF VALVE LEAKING. REPLACED VALVE, OPERATIONAL CHECK NORMAL.