As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
(CAN) AS THE ACFT WAS BEING PULLED OUT OF THE HANGAR, THE PILOTS ARMED THE OXYGEN SYSTEM. SHORTLY AFTER ARMING THE SYS, THE CAPTAIN HEARD A LOUD HISSING NOISE COMING FROM BEHIND THE SIDEWALL. THE ACFT WAS BROUGHT BACK INTO THE HANGAR FOR MAINTENANCE TO INSPECT IT. AN OXYGEN LINE WAS FOUND BURST BEHIND THE SIDEWALL. IT LOOKS LIKE THE OXYGEN LINE HAD NEVER BEEN CHANGED BEFORE.