As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DFW - FLT 3811 - DURING TAXI OUT, GREEN SYSTEM HYD LOW LEVEL ALARM ILLUMINATED. NORMAL BRAKING CONTROL WAS LOST. AIRCRAFT RETURNED TO THE GATE. MAINTENANCE FOUND HYDRAULIC LEAK AT THE GREEN SYSTEM LOW PRESSURE WARNING SWITCH IN THE HYD BAY CAUSED BY FAILED O-RING. REPLACED O-RING AND SERVICED HYD SYSTEM. AIRCRAFT RETURNED TO SERVICE. (X)