Harmonizing up

Air Safety Week, Dec 8, 2003

Transport-category aircraft in Canada must be brought up to the same fire-protection standards now embodied in U.S. and European regulations. Per a Nov. 19 regulation issued by Transport Canada, Class D belly holds must be upgraded to provide the same level of fire protection as the larger Class C belly holds. The action effectively eliminates Class D belly holds and follows earlier regulatory action by the U.S. Federal Aviation Administration (FAA). After the May 1996 crash of a ValuJet DC-9 from a raging fire in its forward Class D belly hold, which was protected only by a fire-resistant liner, the FAA in February 1998 gave U.S. carriers three years to install fire detection and suppression equipment in hundreds of aircraft featuring Class D holds. Operators were given a March 19, 2001, deadline to complete the work or the aircraft would be grounded (see ASW, March 2, 1998). The mandate spurred a mobilization of activity to complete the work on time (see ASW, March 26, 2001).

Operators of an estimated 225 affected aircraft in Canadian registry will have about six months to complete the work, rather than three years. The tighter timeline is based on the fact that many Canadian operators voluntarily have already upgraded their Class D holds to the fire detection and suppression standard of Class C holds. The work remains to be completed on a relatively small number of aircraft, hence the shortened time window in which to accomplish the work.

The deadline is June 1, 2004. Airplanes not upgraded by that date "will be prohibited from operating" until the work is done, according to the regulation. "The intent of these regulatory requirements is to ensure that the same level of protection from the results of in-flight fires is provided to passengers on Canadian-operated commercial transport aeroplanes as on those operated by their U.S. counterparts and expected to be required of European operators in future," the regulation explained. "These regulatory requirements will correct a potentially unsafe condition, increase consumer confidence in the aviation industry, and maintain equivalent levels of safety between the Canadian and American fleets."

The regulation summarizes the difference between Class C and Class D belly holds. It illustrates the work needed to bring the former into alignment with the latter.

In addition, flexible fire liners (i.e., blankets of non-rigid fiberglass construction), where installed, must be replaced with more fire-resistant rigid liners.

As in the United States, the Canadian initiative was required to pass the test of a cost-benefit analysis. In this case, the upgraded fire protection effort was estimated to save more than 40 lives if just one A320 with 119 passengers and crew aboard avoids a catastrophic accident as a result of improved belly hold fire protection. The first-year benefit of the 10-year service life of the upgraded protection was placed at $66 million, or double the fleetwide installation cost estimated at $33 million. This calculation suggests that the statistical value of a life in Canada is around $1.5 million, while the FAA uses a figure of $3 million. (see ASW, Aug. 19, 2002).

Halon suppression of cargo-hold fires will only work as long as the airtight integrity of the compartment remains intact. From the outside, uncontained engine failure penetration or, in-ternally, electrical arcing, may compromise the external skin of the pressure hull, as in the Delta Air Lines [NYSE: DAL] Flight 2030 MD88 event Sept. 17, 1999, at Covington, Ky., and Delta Flight 1518 in Columbia, S.C., on Jan. 3, 2000 (see http://www.ntsb.gov/Recs/letters/2001/A01_03_05.pdf ) and, potentially, the Air Canada B767 water-heater ribbon fire May 13, 2002 (see ASW, June 10, 2002). In addition, this measure has come about also due to the flammable nature of the "environmentally friendly" aerosol propellants now found in spray cans packed in luggage stowed in the belly hold. It might be time to consider building into future aircraft designs the ability to divert engine and APU fire extinguishing charges into cargo holds as a last-ditch method of extinguishing the sort of conflagration that downed ValuJet Flight 592 in 1996. For the full text of the new Canadian regulation, see http://canadagazette.gc.ca/PartII/2003/20031119/pdf/g2-13724.pdf

Belly Hold Fire Protection Compared

Class D: A fire occurring in a Class D cargo or baggage compartment will be
completely confined without endangering the safety of the aeroplane or the
occupants.
Class C: In a Class C cargo or baggage compartment, there is a separate
approved smoke detector or fire detector system to give warning at the
pilot or flight engineer station.

Class D: The compartment volume does not exceed 1,000 cubic feet. For
compartments of 500 cubic feet or less, airflow of 1,500 cubic feet or less
is acceptable.
Class C: There is an approved built-in extinguishing or suppression system
controllable from the cockpit.

Class D: The detection system must provide a visual indication to the
flight crew within one minute after the start of a fire (applies only if
a fire detection system is installed).
Class C: The system must be capable of detecting a fire at a temperature
significantly below that at which the structural integrity of the aeroplane
is substantially decreased.

Source: http://canadagazette.gc.ca/PartII/2003/20031119/pdf/g2-13724.pdf,
pages 2783-2784