As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
FLT 3543 - DFW - AN OXYGEN LEAK FROM OBSERVERS MASK AND DEPLETED ALL THE OXYGEN. TROUBLESHOT, FOUND OXYGEN LINE BEHIND OBSERVERS 02 MASK RUPTURED. REPLACED LINE IAW MM 35-11-03. INSTALLED SERVICEABLE CREW 02 BOTTLE IAW MM 35-11-03. NO LEAKS NOTED AT THIS TIME. AIRCRAFT RETURNED TO SERVICE. (M)