A BD700-1A10 GLOBAL EXPRESS MAINT MANAGER RPTS SEVERAL FAILURES OF PLASTIC OXYGEN HOSES AT THE END FITTINGS. HOSES NORMALLY AT BOTTLE PRESSURE.

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THE ACFT IN QUESTION IS A BOMBARDIER GLOBAL EXPRESS (BD700-1A10). ON TWO SEPARATE OCCASIONS WE HAVE DISCOVERED A FLEXIBLE OXYGEN LINE BURST WHILE ACFT WAS SITTING STATIC IN THE HANGAR OR ON THE RAMP. THE FIRST INSTANCE THE ACFT HAD BEEN IN SERVICE FOR 1432.0 HRS AND 622 CYCLES AND HAD BEEN PARKED FOR APPROX 2 WEEKS ON THE RAMP IN A TROPICAL CLIMATE. WHEN THE FLT CREW CONDUCTED THEIR PREFLT INSPECTION IT WAS NOTED THAT THE OXYGEN SYSTEM QUANTITY WAS INDICATING ZERO PSI ON THE EICAS AND THE DIRECT READING GAUGE ON THE EXTERIOR OF THE ACFT. SERVICING OF THE O2 SYSTEM WAS ATTEMPTED HOWEVER THE PRESSURE REMAINED AT ZERO. UPON FURTHER INVESTIGATION BY THE MAINT TECHNICIAN IT WAS DISCOVERED THAT THE LINE P/N 38911-5-0110 INSTALLED UNDER THE PLT'S SIDE CONSOLE CONNECTING THE PLTS OXYGEN MASK BOX TO THE OXYGEN SUPPLY WAS RUPTURED AT THE END FITTING AS IN THE HOSE HAD COME UN-SWEDGED. A REPLACEMENT LINE WAS ORDERED FROM THE MANUFACTURER AND INSTALLED. AS A PRECAUTION SINCE WE WERE NOT ABLE TO DETERMINE HOW LONG THE OXYGEN STORAGE CYLINDERS HAD BEEN OPEN TO ATMOSPHERIC CONDITIONS THE OXYGEN CYLINDERS WERE REPLACED WITH SERVICEABLE UNITS AND OXYGEN SYSTEM WAS PURGED. ACFT WAS THEN RELEASED FOR SERVICE. THE SECOND INSTANCE OCCURRED SHORTLY AFTER THE FIRST WITH 1461.2 HRS AND 632 CYCLES ON THE ACFT. HOWEVER; THIS TIME LINE P/N 38913-5-0170 CONNECTING THE #3 CYLINDER TO THE ACFT OXYGEN PRESSURE PLUMBING RUPTURED AT THE SWEDGE WHILE OTHER MAINTENANCE WAS BEING PERFORMED IN THE AREA. ALL 4 OXYGEN CYLINDERS WERE SELECTED TO OFF BEFORE COMPLETE DEPLETION OCCURRED. SINCE WE HAD JUST HAD ONE FAILURE AND NOW THIS SECOND; AS A PRECAUTION I CHANGED ALL THE REMAINING ORIGINAL PRESSURIZED OXYGEN SUPPLY LINES BETWEEN THE OXYGEN CYLINDERS AND THE OXYGEN SYSTEM CONTROL PANEL. THESE LINES ARE THE ONLY LINES UNDER CONSTANT PRESSURE FROM THE OXYGEN CYLINDERS. ALL OF THE LINES REPLACED WERE VISUALLY INSPECTED. IT WAS NOTED THAT ONE OF THESE LINES BEGAN TO DEVELOP A BLISTERED APPEARANCE AT ONE OF THE CONNECTORS. THIS LINE AND THE OTHER 2 PREVIOUSLY FAILED LINES WERE TURNED OVER TO THE ACFT MANUFACTURE FOR TESTING. A BOMBARDIER ENGINEER WORKING THIS ISSUE REPORTED TO ME THAT THE LINE WITH THE BLISTER FAILED TO APPROX HALF OF THE CERTIFIED PSI RATING. FURTHER INVESTIGATION REVEALED THAT THE ACFT MANUFACTURER AS WELL AS THE LINE MANUFACTURER ARE BOTH AWARE OF A POSSIBLE MANUFACTURING PROB WITH THE OXYGEN LINES AND ARE VERY SLOW TAKING ACTIONS TO REMEDY THE SIT. BOMBARDIER HAD RESPONDED THAT THESE LINES DO MEET THE REQUIREMENTS SET BY THE FARS AND ARE WAITING APPROVAL TO MAKE AN ENGINEERING CHANGE. HOWEVER; THE CHANGE WILL MORE THAN LIKELY NOT OCCUR FOR SOME TIME WITH THE RECENT BUDGET CUTS. I AM AWARE THAT NUMEROUS OTHER GLOBAL EXPRESS AWARE ACFT OPERATORS HAVE HAD SIMILAR EXPERIENCES WITH THESE LINES AS HAVE SOME BOMBARDIER REGIONAL JET OPERATORS. I FOR THE LIFE OF ME CANNOT UNDERSTAND HOW THESE O2 LINES; MANUFACTURED OUT OF PLASTIC CAN BE CERTIFIED FOR ACFT USE WHEN THEY ARE UNDER CONSTANT PRESSURE FOR THE O2 CYLINDERS. IN MY OPINION THESE LINES WE ORIGINALLY DESIGNED WITH THE INTENT OF SUPPLYING OXYGEN TO PAX SERVICE UNITS FOR THE SHORT DURATION NEEDED WHEN THE OXYGEN MASKS ARE DEPLOYED IN AN EMER. IT IS OBVIOUS TO ME THAT THESE LINES ARE NOT DESIGNED OR CAPABLE OF SAFELY SUPPLYING THE FLT CREW WITH OXYGEN. THESE RANDOM BUSTING EVENTS ALLOW ALL OF THE OXYGEN STORED IN THE CYLINDER TO VENT UNCONTROLLED INTO A HIGHLY ELECTRONIC ENVIRONMENT. THIS IS AN IN-FLT FIREBALL WAITING TO HAPPEN. IN MY OPINION; IF IN FACT THESE LINES ARE MANUFACTURED AND INSTALLED PER THE FAR'S; THE FAR'S NEED TO BE CHANGED. FLEXIBLE OXYGEN PRESSURE LINES UNDER A CONSTANT PRESSURE (NO MATTER HOW HIGH OR LOW THE PRESSURE) SHOULD BE OF THE BRAIDED STAINLESS STEEL TYPE OF LINE. THE BRAIDED SS LINES HAVE PROVEN THEIR DURABILITY AND SAFETY OVER THE PAST DECADES OF USE AND IN THIS CASE WILL PREVENT AN EVENTUAL DISASTER. ACFT MANUFACTURERS SHOULD BE REQUIRED TO AGGRESSIVELY PURSUE CORRECTIVE ACTIONS TO SAFETY EQUIPMENT PROBS. FURTHERMORE THEY SHOULD ALSO BE REQUIRED TO REPORT ISSUES TO THE FAA UPON INITIAL DISCOVERY. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: THE RPTR STATED THERE WAS NO SERVICE BULLETIN ISSUED BY THE MANUFACTURER AND A DISCUSSION WITH ENGINEERING REVEALED NINE FAILURE EVENTS. THE RPTR SAID THESE PLASTIC HOSES SHOULD BE REPLACED WITH BRAIDED STAINLESS STEEL TYPE OF LINE WHICH HAVE BEEN IN USE FOR YEARS. THE RPTR STATED A NUMBER OF SERVICE DIFFICULTY RPTS WERE FILED OUTLINING THIS ONGOING PROB.