What was found
CMH - FLT 0266 - BOTH NR 1 AND NR 2 BLEED VALVES FAILED IN-FLIGHT. EMERGENCY DESCENT. ALL CABIN OXYGEN MASKS DROPPED. PERFORMED BLEED SYSTEM INSPECTION ON BOTH ENGINES PER SIL 36-034 AND RAN ENGINES. NO DEFECTS NOTED. REPLACED ALL OXYGEN MASKS EXCEPT ALL LAVS, ROWS 12, 21, 24, AND 25 RIGHT TO 10 AND 17 LEFT. NR 2 BLEED WAS ON MEL 36-11-07, WHEN PILOT INADVERTENTLY SELECTED ENGINE ANTI-ICE WITHOUT TURNING 1 PACK OFF, THUS CAUSING BLEED FAILURE. (X)