NTSB · Safety Recommendation
Safety Recommendation A-89-107
Recommendation
THE NTSB RECOMMENDS THAT THE FEDERAL AVIATION ADMINISTRATION: REQUIRE SCOTT AVIATION TO MODIFY EXISTING STOCK OF AVIOX GENERATORS TO INCLUDE AN OVERPRESSURE RELIEF DEVICE FOR EACH OXYGEN GENERATOR CANISTER OR REMOVE THEM FROM SERVICE.
Safety Issue and Context
ON FEBRUARY 19, 1988, ABOUT 2130 EST, A BOEING 757, OPERATED BY EASTERN AIRLINES AS FLIGHT 215, EN ROUTE FROM ATLANTA, GEORGIA, TO TUCSON, ARIZONA, WITH 6 CREWMEMBERS AND 131 PASSENGERS ON BOARD, EXPERIENCE AN IN-FLIGHT FIRE CAUSED BY A RUPTURED SOLID-STATE OXYGEN GENERATOR IN THE FORWARD GALLEY. THERE WAS NO DAMAGE TO THE AIRPLANE AND THERE WERE NO INJURIES.
Response History
November 20, 1995 · NTSB Correspondence · FAA
THE BOARD NOTES FURTHER THAT THE THE FAA CONCLUDED THAT THERE WERE NO FACTUAL DATA TO SUPPORT THE ISSUANCE OF AN AIRWORTHINESS DIRECTIVE TO MODIFY OR REMOVE FROM SERVICE THE APPROXIMATELY 76,000 IN-SERVICE SCOTT AVIOX GENERATORS. THE BOARD BELIEVES THAT SCOTT AVIATION'S DECISION TO INSTALL OVERPRESSURE PROTECTION IN NEWLY MANUFACTURED OXYGEN GENERTORS INDICATES THAT THE POTENTIAL FOR OVERPRESSURE PROBLEMS DOES EXIST & THAT IN-SERVICE GENERATORS SHOULD BE MODIFIED WITH OVERPRESSURE PROTECTION OR REPLACE WITH NEWLY MANUFACTURED GENERATORS.
July 8, 1995 · Recipient Response · FAA
THE FAA HAS CONDUCTED EXTENSIVE TESTING OF THE AVIOX PORTABLE OXYGEN UNIT TO EXAMINE THE NEED FOR AN OVERPRESSURE RELIEF DEVICE FOR EACH OXYGEN-GENERATING CANISTER. THE EVALUATION WAS CONDUCTED AT THE FAA TECHNICAL CENTER & INCLUDED PERSONNEL FROM THE NEW YORK AIRCRAFT CERTIFICATION OFFICE. SCOTT AVIATION (THE MANUFACTURER OF THE SOLID-STATE OXYGEN GENERATOR) PARTICIPATED IN THE REVIEW, & THE FAA EVALUATED INFO FROM SCOTT AVIATION RELATIVE TO THIS UNIT. THE RESULT OF THE EVALUATION IS THAT THE INSTALLATION OF AN OVERPRESSURE RELIEF VALVE IN EACH OXYGEN-GENERATING CANSITER WOULD NOT HAVE PREVENTED THE OVERPRESSURIZATION OF THE UNIT.
May 6, 1993 · NTSB Correspondence · FAA
THE FAA STAFF & NTSB STAFF ARE ENGAGED IN DISCUSSIONS CONCERNING A-89-107, & THE FAA IS RECONSIDERING ITS POSITION CONCERNING THIS ISSUE. THEREFORE, THE BOARD CLASSIFIES A-89-107 "OPEN--AWAIT RESPONSE," PENDING RECEIPT OF THE FAA'S FORTHCOMING RESPONSE.
October 28, 1992 · Recipient Response · FAA
THE FAA DOES NOT AGREE WITH RECOMMENDATION. THE FAA CANNOT CONCLUDE THAT AN OVER-PRESSURE RELIEF VALVE FOR EACH OXYGEN GENERATING CANISTER WOULD HAVE PREVENTED THE OVERHEATING OF THE UNIT. PHOTOGRAPHS OF THE UNIT SHOWED NO EVIDENCE OF OVERPRESSURING THE CANISTER (E.G., EXPANSION, DISTORTION, RUPTURE, ELONGATION OF THE CYLINDRICAL PORTION OF THE CANISTER). TESTS WERE CONDUCTED TYRING TO SIMULATE THIS OCCURRENCE; HOWEVER, THE FAILURE COULD NOT BE DUPLICATED DURING THESE TESTS. THE SPACER SHIELD HAD A DENT NEAR THE OUTLET TUBE OF THE ELBOW AND A JOGGLE IN THE CENTER DIAMETRICAL PORTION OF THE SPACER SHIELD, INDICATING THAT THE UNIT MAY HAVE BEEN DROPPED.
CONSEQUENTLY, THE FAA REQUESTED THAT SCOTT AVIATION PERFORM TESTS IN AN ATTEMPT TO SIMULATE THE CONDITION THAT MIGHT HAVE OCCURRED ON THE ACCIDENT AIRCRAFT. REPRESENTATIVES OF THE FAA AND THE LOCKHEED AVIATION COMPANY WERE PRESENT TO OBSERVE THE TESTING. TESTS WERE CONDUCTED ON A STANDARD DUO-PAK PORTABLE UNIT AFTER BEING DROPPED ONTO AN UNCOVERED CONCRETE FLOOR. TESTS WERE ALSO CONDUCTED ON THE UNIT BY MECHANICALLY MODIFYING THE OUTLET FITTING BY TOTALLY REMOVING IT AND SEALING THE ENDCAP. PRESSURES AND TEMPERATURES WERE MEASURED DURING THE 6 TESTS PERFORMED WITH VARIOUS FAILURE CONDITIONS SIMULATED.
THE RESULTS OF THESE TESTS INDICATE THAT INSTALLING A PRESSURE RELIEF DEVICE ON THE CANISTERS WOULD NOT HAVE PREVENTED THE INCIDENT FROM OCCURRING. THE UNIT APPEARS TO HAVE BEEN SEVERELY DAMAGED AND/OR MISHANDLED PRIOR TO OPERATION. THERE HAVE BEEN NO OTHER INCIDENTS OF SIMILAR OCCURRENCE.