ValueJet

From the Federal Regulatory Brief, Feb. 8, 2007:

CRASH OF VALUJET FLIGHT 596: The National Transportation Safety Board (NTSB) determined that one of the probable causes of the May 11, 1996 crash of ValuJet Airlines flight No. 596 was a fire in the airplane's cargo compartment initiated and enhanced by the actuation of one or more chemical oxygen generators carried as cargo in violation of requirements in the Hazardous Materials Regulations (HMR; 49 CFR Parts 171 through 180). Recommendations issued by the NTSB following this tragedy, in which 110 lives were lost, addressed both the initiation of the fire by the improperly packaged generators (which produce external heat when activated) and the possible enhancement of an aircraft cargo compartment fire (of any origin) by the oxygen produced by the generators or other cargo, such as gaseous oxygen in cylinders and other oxidizing agents.

WHICH REQUIREMENTS APPLY? When installed on an aircraft or provided during flight for the use of passengers or crew members, compressed oxygen in cylinders and oxygen generators are subject to requirements in FAA's regulations in Title 14 of the Code of Federal Regulations, and are not subject to the HMR. When transported as cargo, cylinders of compressed oxygen and oxygen generators are subject to requirements in the HMR. Air carriers routinely transport their own oxygen cylinders and oxygen generators as replacement items for use on other aircraft. Some also transport cylinders for their passengers or other customers.

FINAL RULE: Because of safety concerns associated with the air transportation of compressed oxygen cylinders and oxygen generators, PHMSA and FFA are amending the HMR to require cylinders of compressed oxygen and chemical oxygen generators to be transported in an outer packaging that: (1) Meets the same flame penetration resistance standards as required for cargo compartment sidewalls and ceiling panels in transport category airplanes; and (2) provides certain thermal protection capabilities so as to retain its contents during an otherwise controllable cargo compartment fire. The outer packaging standard that is being adopted addresses two safety concerns: (1) Protecting a cylinder and an oxygen generator that could be exposed directly to flames from a fire; and (2) protecting a cylinder and an oxygen generator that could be exposed indirectly to heat from a fire. These performance requirements must remain in effect for the entire service life of the outer packaging.

OUTER PACKAGING REQUIREMENTS: Under this final rule, an outer packaging for a cylinder containing compressed oxygen or another oxidizing gas and a package containing an oxygen generator must meet the standards in Part III of Appendix F to 14 CFR Part 25, Test Method to Determine Flame Penetration Resistance of Cargo Compartment Liners. An outer packaging's materials of construction must prevent penetration by a flame of 1,700 degrees F for five minutes, in accordance with Part III of Appendix F, paragraphs (a)(3) and (f)(5) of 14 CFR Part 25.
In addition, a cylinder of compressed oxygen or another oxidizing gas must remain below the temperature at which its pressure relief device would activate and an oxygen generator must not actuate when exposed to a temperature of at least 400 degrees F for three hours. The 400 degree F temperature is the estimated mean temperature of a cargo compartment during a halon-suppressed fire.\1\ Three hours and 27 minutes is the maximum estimated diversion time world-wide; based on an aircraft flying a southern route over the Pacific Ocean. Data collected during the FAA tests indicate that, on average, a 3AA oxygen cylinder with a pressure relief device set at cylinder test pressure will open when the cylinder reaches a temperature of approximately 300 degrees F. This result is consistent with calculations performed by PHMSA. In analyzing PRD function, PHMSA calculated that a 3HT cylinder with a PRD set at 90% of cylinder test pressure will vent at temperatures greater than 220 degrees F. In order to assure an adequate safety margin for all authorized cylinders, including 3HT cylinders, we are amending the HMR to require cylinders of compressed oxygen and other oxidizing gases, which are contained in the specified outer packaging, to maintain an external temperature below 93 degrees C (199 degrees F) when exposed to a 400 degree F temperature for three hours.
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\1\ The FAA currently is evaluating other non-ozone-depleting suppression agents that could eventually be used in cargo compartments. Some of these agents can maintain an adequate level of safety in the compartment, but the mean temperature may be slightly higher than 400 degrees F, which is the level found during typical halon-suppressed fires. If an alternate agent is used, the oven soak temperature level may need to be adjusted accordingly.
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AMENDMENTS: 49 CFR Chapter I is amended as follows:

In Section 171.11, paragraph (d)(16) is revised to read as follows:

Section 171.11 Use of ICAO Technical Instructions.

* * * * *
(d) * * *
(16) A package containing Oxygen, compressed, or any of the following oxidizing gases must be packaged as required by parts 173 and 178 of this subchapter: carbon dioxide and oxygen mixtures, compressed; compressed gas, oxidizing, n.o.s.; liquefied gas, oxidizing, n.o.s.; nitrogen trifluoride; and nitrous oxide.
* * * * *


In the Hazardous Materials Table in Section 172.101, for the shipping name “Air, refrigerated liquid, (cryogenic liquid),” Column (9B) is revised to read “Forbidden.”


In the Hazardous Materials Table in Section 172.101, for the shipping name “Oxygen, compressed,” in column (7), Special Provision “A52” is removed.


In the Hazardous Materials Table in Section 172.101, for the shipping name “Oxygen generator, chemical,” in Column (7), Special Provisions “60, A51” are removed and Column (8B) is revised to read “168.”


In Section 172.102, in paragraph (c)(1), Special Provisions “60” is removed.


In Section 172.102, in paragraph (c)(2), Special Provisions “A51” and “A52” are removed.


Section 173.168 is added to read as follows:

Section 173.168 Chemical oxygen generators.

An oxygen generator, chemical (defined in Section 171.8 of this subchapter) may be transported only under the following conditions:

(a) Approval. A chemical oxygen generator that is shipped with a means of initiation attached must be classed and approved by the Associate Administrator in accordance with the procedures specified in Section 173.56 of this subchapter.

(b) Impact resistance. A chemical oxygen generator, without any packaging, must be capable of withstanding a 1.8 meter drop onto a rigid, non-resilient, flat and horizontal surface, in the position most likely to cause actuation or loss of contents.

(c) Protection against inadvertent actuation. A chemical oxygen generator must incorporate one of the following means of preventing inadvertent actuation:

(1) A chemical oxygen generator that is not installed in protective breathing equipment (PBE):
(i) Mechanically actuated devices:
(A) Two pins, installed so that each is independently capable of preventing the actuator from striking the primer;
(B) One pin and one retaining ring, each installed so that each is independently capable of preventing the actuator from striking the primer; or
(C) A cover securely installed over the primer and a pin installed so as to prevent the actuator from striking the primer and cover.
(ii) Electrically actuated devices: The electrical leads must be mechanically shorted and the mechanical short must be shielded in metal foil.
(iii) Devices with a primer but no actuator: A chemical oxygen generator that has a primer but no actuating mechanism must have a protective cover over the primer to prevent actuation from external impact.
(2) A chemical oxygen generator installed in a PBE must contain a pin installed so as to prevent the actuator from striking the primer, and be placed in a protective bag, pouch, case or cover such that the protective breathing equipment is fully enclosed in such a manner that the protective bag, pouch, case or cover prevents unintentional actuation of the oxygen generator.

(d) Packaging. After September 30, 2009 a chemical oxygen generator and a chemical oxygen generator installed in equipment, (e.g., a PBE) must be placed in a rigid outer packaging that—

(1) Conforms to the requirements of either:
(i) Part 178, subparts L and M, of this subchapter at the Packing
Group I or II performance level; or
(ii) The performance criteria in Air Transport Association (ATA) Specification No. 300 for a Category I Shipping Container.
(2) With its contents, is capable of meeting the following additional requirements when transported by cargo-only aircraft:
(i) The Flame Penetration Resistance Test in part III of Appendix F to 14 CFR part 25, modified as follows:
(A) At least three specimens of the outer packaging materials must
be tested;
(B) Each test must be conducted on a flat 16 inch x 24 inch test specimen mounted in the horizontal ceiling position of the test apparatus to represent the outer packaging design;
(C) Testing must be conducted on all design features (latches, seams, hinges, etc.) affecting the ability of the outer packaging to safely prevent the passage of fire in the horizontal ceiling position; and
(D) There must be no flame penetration of any specimen within 5 minutes after application of the flame source, and the maximum allowable temperature at a point 4 inches above the test specimen, centered over the burner cone, must not exceed 205 degrees C (400 degrees F).
(ii) The Thermal Resistance Test specified in Appendix D to part 178 of this subchapter.
(iii) None of the following conditions may occur when one generator in the package is actuated:
(A) Actuation of other generators in the package;
(B) Ignition of the packaging materials; and
(C) A temperature above 100 degrees C (212 degrees F) on the outside surface temperature of the package.
(iv) All features of the packaging must be in good condition, including all latches, hinges, seams, and other features, and the packaging must be free from perforations, cracks, dents, or other abrasions that may negatively affect the flame penetration resistance and thermal resistance characteristics of the packaging, verified by a visual inspection of the package before each shipment.

(e) Equipment marking. The outside surface of a chemical oxygen generator must be marked to indicate the presence of an oxygen generator (e.g., “oxygen generator, chemical”). The outside surface of equipment containing a chemical oxygen generator that is not readily apparent (e.g., a sealed passenger service unit) must be clearly marked to indicate the presence of the oxygen generator (example: “Oxygen Generator Inside”).

(f) Items forbidden in air transportation.
(1) A chemical oxygen generator is forbidden for transportation on board a passenger-carrying aircraft.
(2) A chemical oxygen generator is forbidden for transportation by both passenger-carrying and cargo-only aircraft after:
(i) The manufacturer's expiration date; or
(ii) The contents of the generator have been expended.


In Section 173.302a, paragraph (f) is added to read as follows:

Section 173.302a Additional requirements for shipment of nonliquefied (permanent) compressed gases in specification cylinders.

* * * * *
(f) Compressed oxygen and oxidizing gases. A cylinder containing oxygen, compressed; compressed gas, oxidizing, n.o.s.; or nitrogen trifluoride is authorized for transportation by aircraft only when it meets the following requirements:

(1) Only DOT specification 3A, 3AA, 3AL, and 3HT cylinders, and UN pressure receptacles ISO 9809-1, ISO 9809-2, ISO 9809-3 and ISO 7866 cylinders are authorized.
(2) Cylinders must be equipped with a pressure relief device in accordance with Section 173.301(f) and, beginning with the first requalification due after October 1, 2007:
(i) The rated burst pressure of a rupture disc for DOT 3A, 3AA, and 3AL cylinders must be 100% of the cylinder minimum test pressure with a tolerance of -10 to plus zero percent; and
(ii) The rated burst pressure of a rupture disc for a 3HT must be 90% of the cylinder minimum test pressure with a tolerance of -10 to plus zero percent.
(3) After September 30, 2009, the cylinder must be placed in a rigid outer packaging that--
(i) Conforms to the requirements of either part 178, subparts L and M of this subchapter at the Packing Group I or II performance level or the performance criteria in Air Transport Association (ATA) Specification No. 300 for a Category I Shipping Container;
(ii) Is capable of passing, as demonstrated by design testing, the Flame Penetration Resistance Test in part III of Appendix F to 14 CFR part 25, modified as follows:
(A) At least three specimens of the outer packagings materials must be tested;
(B) Each test must be conducted on a flat 16 inch x 24 inch test specimen mounted in the horizontal ceiling position of the test apparatus to represent the outer packaging design;
(C) Testing must be conducted on all design features (latches, seams, hinges, etc.) affecting the ability of the outer packaging to safely prevent the passage of fire in the horizontal ceiling position; and
(D) There must be no flame penetration of any specimen within 5 minutes after application of the flame source and the maximum allowable temperature at a point 4 inches above the test specimen, centered over the burner cone, must not exceed 205 degrees C (400 degrees F); and
(iii) Prior to each shipment, passes a visual inspection that verifies that all features of the packaging are in good condition, including all latches, hinges, seams, and other features, and that the packaging is free from perforations, cracks, dents, or other abrasions that may negatively affect the flame penetration resistance and thermal resistance characteristics of the packaging.
(4) After September 30, 2009, the cylinder and the outer packaging must be capable of passing, as demonstrated by design testing, the Thermal Resistance Test specified in Appendix D to part 178 of this subchapter.
(5) The cylinder and the outer packaging must both be marked and labeled in accordance with part 172, subparts D and E of this subchapter.
(6) A cylinder of compressed oxygen that has been furnished by an aircraft operator to a passenger in accordance with 14 CFR 121.574, 125.219, and 135.91 is excepted from the outer packaging requirements of paragraph (f)(3) of this section.


In Section 173.304a, paragraph (f) is added to read as follows:

Section 173.304a Additional requirements for shipment of liquefied compressed gases in specification cylinders.

* * * * *
(f) Oxidizing gases. A cylinder containing carbon dioxide and oxygen mixture, compressed; liquefied gas, oxidizing, n.o.s.; or nitrous oxide is authorized for transportation by aircraft only when it meets the following requirements:

(1) Only DOT specification 3A, 3AA, 3AL, and 3HT cylinders, and UN pressure receptacles ISO 9809-1, ISO 9809-2, ISO 9809-3 and ISO 7866 cylinders are authorized.
(2) Cylinders must be equipped with a pressure relief device in accordance with Section 173.301(f) and, beginning with the first requalification due after October 1, 2007:
(i) The rated burst pressure of a rupture disc for DOT 3A, 3AA, and 3AL cylinders must be 100% of the cylinder minimum test pressure with a tolerance of -10 to plus zero percent; and
(ii) The rated burst pressure of a rupture disc for a 3HT must be 90% of the cylinder minimum test pressure with a tolerance of -10 to plus zero percent.
(3) After September 30, 2009, the cylinder must be placed in a rigid outer packaging that--
(i) Conforms to the requirements of either part 178, subparts L and M, of this subchapter at the Packing Group I or II performance level, or the performance criteria in Air Transport Association (ATA) Specification No. 300 for a Category I Shipping Container;
(ii) Is capable of passing, as demonstrated by design testing, the Flame Penetration Resistance Test in part III of Appendix F to 14 CFR part 25, modified as follows:
(A) At least three specimens of the outer packaging materials must be tested;
(B) Each test must be conducted on a flat 16 inch x 24 inch test specimen mounted in the horizontal ceiling position of the test apparatus to represent the outer packaging design;
(C) Testing must be conducted on all design features (latches, seams, hinges, etc.) affecting the ability of the outer packaging to safely prevent the passage of fire in the horizontal ceiling position; and
(D) There must be no flame penetration of any specimen within 5 minutes after application of the flame source and the maximum allowable temperature at a point 4 inches above the test specimen, centered over the burner cone, must not exceed 205 degrees C (400 degrees F); and
(iii) Prior to each shipment, passes a visual inspection that verifies that all features of the packaging are in good condition, including all latches, hinges, seams, and other features, and the packaging is free from perforations, cracks, dents, or other abrasions that may negatively affect the flame penetration resistance and thermal resistance characteristics of the container.
(4) After September 30, 2009, the cylinder and the outer packaging must be capable of passing, as demonstrated by design testing, the
Thermal Resistance Test specified in Appendix D to part 178 of this subchapter.
(5) The cylinder and the outer packaging must both be marked and labeled in accordance with part 172, subparts D and E of this subchapter.
(6) A cylinder of compressed oxygen that has been furnished by an aircraft operator to a passenger in accordance with 14 CFR 121.574, 125.219, and 135.91 is excepted from the outer packaging requirements of paragraph (f)(3) of this section.


175.501 is revised to read as follows:

Section 175.501 Special requirements for oxidizers and compressed oxygen.

(a) Compressed oxygen, when properly labeled Oxidizer or Oxygen, may be loaded and transported as provided in this section. Except for Oxygen, compressed, no person may load or transport a hazardous material for which an OXIDIZER label is required under this subchapter in an inaccessible cargo compartment that does not have a fire or smoke detection system and a fire suppression system.

(b) In addition to the quantity limitations prescribed in Section 175.75, no more than a combined total of six cylinders of compressed oxygen may be stowed on an aircraft in the inaccessible aircraft cargo compartment(s) that do not have fire or smoke detection systems and fire suppression systems.

(c) When loaded into a passenger-carrying aircraft or in an inaccessible cargo location on a cargo-only aircraft, cylinders of compressed oxygen must be stowed horizontally on the floor or as close as practicable to the floor of the cargo compartment or unit load device. This provision does not apply to cylinders stowed in the cabin of the aircraft in accordance with paragraph (e) of this section.

(d) When transported in a Class B aircraft cargo compartment (see 14 CFR 25.857(b)) or its equivalent (i.e., an accessible cargo compartment equipped with a fire or smoke detection system, but not a fire suppression system), cylinders of compressed oxygen must be loaded in a manner that a crew member can see, handle and, when size and weight permit, separate the cylinders from other cargo during flight. No more than six cylinders of compressed oxygen and, in addition, one cylinder of medical-use compressed oxygen per passenger needing oxygen at destination--with a rated capacity of 1000 L (34 cubic feet) or less of oxygen--may be carried in a Class B aircraft cargo compartment or its equivalent.

(e) A cylinder containing medical-use compressed oxygen, owned or leased by an aircraft operator or offered for transportation by a passenger needing it for personal medical use at destination, may be carried in the cabin of a passenger-carrying aircraft in accordance with the following provisions:

(1) No more than six cylinders belonging to the aircraft operator and, in addition, no more than one cylinder per passenger needing the oxygen at destination, may be transported in the cabin of the aircraft under the provisions of this paragraph (e);
(2) The rated capacity of each cylinder may not exceed 1,000 L (34 cubic feet);
(3) Each cylinder must conform to the provisions of this subchapter and be placed in:
(i) An outer packaging that conforms to the performance criteria of Air Transport Association (ATA) Specification 300 for a Category I Shipping Container; or
(ii) A metal, plastic or wood outer packaging that conforms to a UN standard at the Packing Group I or II performance level.
(4) The aircraft operator shall securely stow the cylinder in its overpack or outer packaging in the cabin of the aircraft and shall notify the pilot-in-command as specified in Section 175.33 of this part; and
(5) Shipments under this paragraph (e) are not subject to--
(i) Sections 173.302(f) and 173.304a(f) of this subchapter, subpart C of part 172 of this subchapter, and, for passengers only, subpart H of part 172 of this subchapter;
(ii) Section 173.25(a)(4) of this subchapter; and
(iii) Paragraph (b) of this section.


A new Appendix D to part 178 is added to read as follows:

Appendix D to Part 178--Thermal Resistance Test

1. Scope. This test method evaluates the thermal resistance capabilities of a compressed oxygen generator and the outer packaging for a cylinder of compressed oxygen or other oxidizing gas and an oxygen generator. When exposed to a temperature of 205 degrees C (400 degrees F) for a period of not less than three hours, the outer surface of the cylinder may not exceed a temperature of 93 degrees C (199 degrees F) and the oxygen generator must not actuate.
2. Apparatus.
2.1 Test Oven. The oven must be large enough in size to fully house the test outer package without clearance problems. The test oven must be capable of maintaining a minimum steady state temperature of 205 degrees C (400 degrees F).
2.2 Thermocouples. At least three thermocouples must be used to monitor the temperature inside the oven and an additional three thermocouples must be used to monitor the temperature of the cylinder. The thermocouples must be \1/16\ inch, ceramic packed, metal sheathed, type K (Chromel-Alumel), grounded junction with a nominal 30 American wire gauge (AWG) size conductor. The thermocouples measuring the temperature inside the oven must be placed at varying heights to ensure even temperature and proper heat-soak conditions. For the thermocouples measuring the temperature of the cylinder: (1) two of them must be placed on the outer cylinder side wall at approximately 2 inches (5 cm) from the top and bottom shoulders of the cylinder; and (2) one must be placed on the cylinder valve body near the pressure relief device.
2.3 Instrumentation. A calibrated recording device or a computerized data acquisition system with an appropriate range should be provided to measure and record the outputs of the thermocouples.
3. Test Specimen.
3.1 Specimen Configuration. Each outer package material type and design must be tested, including any features such as handles, latches, fastening systems, etc., that may compromise the ability of the outer package to provide thermal protection.
3.2 Test Specimen Mounting. The tested outer package must be supported at the four corners using fire brick or other suitable means. The bottom surface of the outer package must be exposed to allow exposure to heat.
4. Preparation for Testing.
4.1 It is recommended that the cylinder be closed at ambient temperature and configured as when filled with a valve and pressure relief device. The oxygen generator must be filled and may be tested with or without packaging.
4.2 Place the package or generator onto supporting bricks or a stand inside the test oven in such a manner to ensure even temperature flow.
5. Test Procedure.
5.1 Close oven door and check for proper reading on thermocouples.
5.2 Raise the temperature of the oven to a minimum temperature
of 205 degrees C 2 degrees C (400 degrees F 5 degrees F). Maintain a minimum oven temperature of 205 degrees C < plus-minus> 2 degrees C (400 degrees F 5 degrees F) for at least three hours. Exposure time begins when the oven steady state temperature reaches a minimum of 205 degrees C 2 degrees C (400 degrees F 5 degrees F).
5.3 At the conclusion of the three-hour period, the outer package may be removed from the oven and allowed to cool naturally.
6. Recordkeeping.
6.1 Record a complete description of the material being tested, including the manufacturer, size of cylinder, etc.
6.2 Record any observations regarding the behavior of the test specimen during exposure, such as smoke production, delamination, resin ignition, and time of occurrence of each event.
6.3 Record the temperature and time history of the cylinder temperature during the entire test for each thermocouple location. Temperature measurements must be recorded at intervals of not more than five (5) minutes. Record the maximum temperatures achieved at all three thermocouple locations and the corresponding time.
7. Requirements.
7.1 For a cylinder, the outer package must provide adequate protection such that the outer surface of the cylinder and valve does not exceed a temperature of 93 degrees C (199 degrees F) at any of the three points where the thermocouples are located.
7.2 For an oxygen generator, the generator must not actuate.