As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
ORD - FLT 0000 - DURING PRE-FLIGHT AT 303 OHMS ON 5-2-99, CREW FOUND ALL PASSENGER OXYGEN MASKS DEPLOYED. AIRCRAFT STAYED AT GATE WITH NO FURTHER PROBLEMS. MAINTENANCE INSPECTED AND RESET OXYGEN SYSTEM AND RE-STOWED ALL PASSENGER OXYGEN MASKS. OPS CHECK OK. AIRCRAFT WAS RELASED AND APPROVED FOR RETURN TO SERVICE. (X)