Narrative:

Emergency escape slide failed to deploy during shop functional test. The slide bottle lanyard was pulled and the regulator bfg P/north 4a3857-1 failed to fire and inflate the slide. This is the third time this regulator has failed to operate. The first time was in the fall of 2002 and the regulator was sent to bfg for examination. No defects were noted. On thur/mar/03 south/north X failed to fire and on mon/mar sn Y failed to fire. Air carrier X service report. Many misfirings have been recorded during the testing of the above regulator in the ZZZ oxygen shop where I work. Internal examination has found defects and metal particles in the regulating section of the valve. It is unknown to this date what has caused the no fire events we have had. Management has requested that we return the valves back to bfg for evaluation. We have talked to the bfgoodrich engineering department several times. I feel that the design of this regulator is deficient in that there is no positive mechanical means to ensure that the regulator valve will open and discharge the bottle when the lanyard is pulled. The belleville washers in the pressure regulating section of the valve are also deficient evidenced by the fact that 50 percent of the regulators tested on our pressure test bench fail. The washers have been found to be chaffing and rubbing on the cylinder bore and regulator adjusting screw introducing metal particles to the regulator. A complete independent review of the design and operation of this series regulator is in order. Firing rod must move upward in order for valve to fire. No positive mechanical linkage to lanyard to ensure that rod moves up investigation needs to be made to find out what has caused rod to stick which results in a 'no fire' situation 'no fire' valves found at air carrier X are currently at bfg awaiting evaluation. Bfg reported to air carrier X that they have recorded 15 'no fire' reports from A330 and A340 operators. 7 were on aircraft and the remainder in shop checks they forgot to count the first valve we sent to them and did not evaluate it for the 'no fire' event. Callback conversation with reporter revealed the following information: the reporter states the escape slide problem is limited to the airbus 330 and 340 which use the same escape slide pressure regulator. The reporter stated that three of the shop escape slide deployments that failed were traced to failed pressure regulators that did not open. The reporter said on disassembly metal particles are found throughout the regulator and are coming from the belleville spring washers which are chaffing on each other, the adjuster and the valve body which contains the spring. The reporter stated the carrier forbids the shop technicians from repairing this regulator and requires the unit to be sent to the manufacturer for repair. The reporter said the manufacturer has reported to the carrier that they have recorded 15 failures of this regulator from A330 and 340 operators. The reporter states that due to the serious nature of the consequences this regulator can cause a major redesign should be made.

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Original NASA ASRS Text

Title: AN ESCAPE SLIDE SHOP TECHNICIAN RPTS A PATTERN OF ESCAPE SLIDES FAILING TO DEPLOY DURING SHOP TESTS. PROB TRACED TO PRESSURE REGULATOR.

Narrative: EMER ESCAPE SLIDE FAILED TO DEPLOY DURING SHOP FUNCTIONAL TEST. THE SLIDE BOTTLE LANYARD WAS PULLED AND THE REGULATOR BFG P/N 4A3857-1 FAILED TO FIRE AND INFLATE THE SLIDE. THIS IS THE THIRD TIME THIS REGULATOR HAS FAILED TO OPERATE. THE FIRST TIME WAS IN THE FALL OF 2002 AND THE REGULATOR WAS SENT TO BFG FOR EXAMINATION. NO DEFECTS WERE NOTED. ON THUR/MAR/03 S/N X FAILED TO FIRE AND ON MON/MAR SN Y FAILED TO FIRE. ACR X SVC RPT. MANY MISFIRINGS HAVE BEEN RECORDED DURING THE TESTING OF THE ABOVE REGULATOR IN THE ZZZ OXYGEN SHOP WHERE I WORK. INTERNAL EXAMINATION HAS FOUND DEFECTS AND METAL PARTICLES IN THE REGULATING SECTION OF THE VALVE. IT IS UNKNOWN TO THIS DATE WHAT HAS CAUSED THE NO FIRE EVENTS WE HAVE HAD. MGMNT HAS REQUESTED THAT WE RETURN THE VALVES BACK TO BFG FOR EVALUATION. WE HAVE TALKED TO THE BFGOODRICH ENGINEERING DEPT SEVERAL TIMES. I FEEL THAT THE DESIGN OF THIS REGULATOR IS DEFICIENT IN THAT THERE IS NO POSITIVE MECHANICAL MEANS TO ENSURE THAT THE REGULATOR VALVE WILL OPEN AND DISCHARGE THE BOTTLE WHEN THE LANYARD IS PULLED. THE BELLEVILLE WASHERS IN THE PRESSURE REGULATING SECTION OF THE VALVE ARE ALSO DEFICIENT EVIDENCED BY THE FACT THAT 50 PERCENT OF THE REGULATORS TESTED ON OUR PRESSURE TEST BENCH FAIL. THE WASHERS HAVE BEEN FOUND TO BE CHAFFING AND RUBBING ON THE CYLINDER BORE AND REGULATOR ADJUSTING SCREW INTRODUCING METAL PARTICLES TO THE REGULATOR. A COMPLETE INDEPENDENT REVIEW OF THE DESIGN AND OPERATION OF THIS SERIES REGULATOR IS IN ORDER. FIRING ROD MUST MOVE UPWARD IN ORDER FOR VALVE TO FIRE. NO POSITIVE MECHANICAL LINKAGE TO LANYARD TO ENSURE THAT ROD MOVES UP INVESTIGATION NEEDS TO BE MADE TO FIND OUT WHAT HAS CAUSED ROD TO STICK WHICH RESULTS IN A 'NO FIRE' SIT 'NO FIRE' VALVES FOUND AT ACR X ARE CURRENTLY AT BFG AWAITING EVALUATION. BFG RPTED TO ACR X THAT THEY HAVE RECORDED 15 'NO FIRE' RPTS FROM A330 AND A340 OPERATORS. 7 WERE ON ACFT AND THE REMAINDER IN SHOP CHECKS THEY FORGOT TO COUNT THE FIRST VALVE WE SENT TO THEM AND DID NOT EVALUATE IT FOR THE 'NO FIRE' EVENT. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: THE RPTR STATES THE ESCAPE SLIDE PROBLEM IS LIMITED TO THE AIRBUS 330 AND 340 WHICH USE THE SAME ESCAPE SLIDE PRESSURE REGULATOR. THE RPTR STATED THAT THREE OF THE SHOP ESCAPE SLIDE DEPLOYMENTS THAT FAILED WERE TRACED TO FAILED PRESSURE REGULATORS THAT DID NOT OPEN. THE RPTR SAID ON DISASSEMBLY METAL PARTICLES ARE FOUND THROUGHOUT THE REGULATOR AND ARE COMING FROM THE BELLEVILLE SPRING WASHERS WHICH ARE CHAFFING ON EACH OTHER, THE ADJUSTER AND THE VALVE BODY WHICH CONTAINS THE SPRING. THE RPTR STATED THE CARRIER FORBIDS THE SHOP TECHNICIANS FROM REPAIRING THIS REGULATOR AND REQUIRES THE UNIT TO BE SENT TO THE MANUFACTURER FOR REPAIR. THE RPTR SAID THE MANUFACTURER HAS RPTED TO THE CARRIER THAT THEY HAVE RECORDED 15 FAILURES OF THIS REGULATOR FROM A330 AND 340 OPERATORS. THE RPTR STATES THAT DUE TO THE SERIOUS NATURE OF THE CONSEQUENCES THIS REGULATOR CAN CAUSE A MAJOR REDESIGN SHOULD BE MADE.

Data retrieved from NASA's ASRS site as of July 2007 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.