Notation 6818: The National Transportation Safety Board has reviewed your Notice of Proposed Rulemaking (NPRM), Docket No. HM-224A, Prohibition of Oxidizers Aboard Aircraft, published on December 30, 1996. The notice proposes prohibiting the carriage of oxidizers, including compressed oxygen, in Class D compartments of passenger-carrying and cargo aircraft.
The notice further proposes eliminating an exception for the transportation of personal chemical oxygen generators as checked baggage, creating a shipping name that specifically identifies chemical oxygen generators, requiring special approval for chemical oxygen generators, and initiating a study to assess the risks associated with the transportation of hazardous materials, other than oxidizers, in aircraft cargo compartments.
The Safety Board has expressed concern about the inadequacies of Class D cargo compartments for some time. On August 8, 1984, the Federal Aviation Administration (FAA) issued a notice of proposed rulemaking, Notice 84-11, that addressed the problem of fire containment in cargo compartments by specifying a new test method for determining the flame penetration resistance of compartment liners.
When the Safety Board provided comments on this rulemaking on October 9, 1984, it advised the FAA that although proposed flame penetration tests were more stringent than previous ones, a fire should not be allowed to persist in any state of intensity in an airplane without the flight crew's knowledge, and that a fire detection system should be required in Class D cargo compartments. While the final rule issued on May 16, 1986, required improved flame penetration resistance for compartment liners, it did not require fire detection systems.
On October 24, 1988, as a result of a February 3, 1988, in-flight tire involving a hydrogen peroxide solution (an oxidizer) aboard an American Airlines DC-9-83 (flight 132) en route to Nashville Metropolitan Airport, Nashville, Tennessee, the Safety Board issued Safety Recommendation A-88-122, which urged the FAA to require fire/smoke detection systems for all Class D cargo compartments. The Safety Board stated that because the cargo compartment on flight 132 was not equipped with fire or smoke dctection systems, the cockpit crew had no way of detecting the safety threat to the airplane until smoke and fumes reached the passenger cabin.
Further, after the smoke was detected in the passenger cabin, the cockpit crew had no means of identifying the fire's location. On August 10, 1993, the FAA responded to Safety Recommendation A-88-l22 by stating that it did not believe that fire/smoke detection and fire extinguishment systems would provide a significant degree of protection to airplane occupants and that it had terminated its rulemaking action to require such systems. On October 14, 1993, Safety Recommendation A-88-122 was classified "Closed--Unacceptable Action."
The Safety Board has investigated at least two other incidents where oxidizers or oxidizing materials, transported as cargo, were believed to have started in-flight fires. One inflight fire occurred aboard a Pan American World Airways Boeing 707-32lC after nitric acid (a corrosive and oxidizing material) leaked from a shipment. Smoke filled the cockpit and the plane crashed on approach to Logan International Airport, Boston, Massachusetts, on November 3, 1973. In the other incident, an in-flight fire occurred on July 16, 1986, aboard a Federal Express Boeing 727-1 OOA after nitric acid leaked. When smoke was detected, the aircraft diverted and landed safely in Cincinnati, Ohio.
On May 31, 1996, Safety Recommendations A-96-28 and -30 were issued as a result of the Safety Board's investigation of the accident involving an in-flight fire on ValuJet flight 592 in the Everglades near Miami, Florida, on May 11, 1996. Preliminary evidence indicated that five cardboard boxes of chemical oxygen generators, most with unexpended oxidizer cores, were loaded on this aircraft in a Class D cargo compartment.
The parallel recommendations urged the Research and Special Programs Administration (RSPA) and the Federal Aviation Administration (FAA) to permanently prohibit the transportation of oxidizers and oxidizing materials (for example, nitric acid) in cargo compartments that do not have fire or smoke detection systems. RSPA and the FAA agreed with these recommendations and on August 19, 1996, Safety Recommendations A-96-28 and -30 were classified "Open--Acceptable Response" pending completion of a final rule.
Class D cargo compartments have not been required to have smoke and fire detection systems because they were designed to contain fire damage by use of flame-resistant compartment liners and to suppress a fire involving combustibles by limiting the oxygen available to support combustion. Oxidizers and certain other hazardous materials, however, can neutralize the latter design safeguard by generating their own oxygen. A leaking cylinder filled with compressed oxygen could also provide an oxygen source for a fire. Further, the pressure relief device on a cylinder of compressed oxygen can open when exposed to sufficient heat from a fire.
The Safety Board supports prohibiting the carriage of oxidizers, including compressed oxygen, in Class D compartments in passenger-carrying and cargo aircraft because these compartments do not have smoke and fire detection systems and because oxidizers, including compressed oxygen, can provide a source of oxygen that will neutralize the compartment's design feature to suppress a fire by limiting the oxygen available to support combustion.
The NPRM also proposes eliminating the exception provided for personal oxygen generators that meet the conditions of Title 49 Code of Federal Regulations (CFR) Section 175.1 0(a)(24) to be carried on aircraft as checked baggage. Like the chemical oxygen generators installed in aircraft, these personal oxygen generators contain oxidizers that, when actuated, produce oxygen. This exception currently permits placement of oxidizers in cargo compartments that do not have fire or smoke detection systems and that are designed to suppress a fire by limiting the oxygen available to support combustion. Therefore, the Safety Board supports eliminating this exception.
The Safety Board is concerned that the rulemaking does not include the prohibition of the limited quantities of oxidizers that are shipped as consumer commodities. l For example, section 173.152 allows the shipment of inner packages that contain over 2 Y:, times the net quantity of sodium chlorate contained in each of the chemical oxygen generators that were loaded on ValuJet flight 592, provided they meet the definition of a consumer commodity. Section 172.101 permits loading a gross weight of 30 kilograms per package of consumer commodities in both passenger and cargo aircraft.
Further, the consumer commodity exception allows these materials to be shipped without an oxidizer label on the package to warn air carrier personnel that the package contains an oxidizer. This exception currently permits the placement of oxidizers in cargo compartments that do not have fire or smoke detection systems and are designed to suppress a fire by limiting the oxygen available to support combustion. The Safety Board therefore believes that the consumer commodity exception for oxidizers should also be eliminated.
RSPA proposes the creation of a new shipping description for chemical oxygen generators that more accurately describes the generators. The current shipping name used for the generators, "Oxidizing solid, N.O.S.," does not address the explosives contained in many types of actuators or the hazards posed by a device capable of initiating and sustaining a reaction that generates both heat and oxygen. The Safety Board supports development of a specific shipping description for chemical oxygen generators that more accurately describes the product shipped and its hazard char