Simon Elliott/LONDON

THE UK CIVIL Aviation Authority will award a contract to design and build an aircraft-cabin hidden-fire test rig by the end of this month. The system will be used to test replacements for Halon 1211, which is used in aircraft-cabin fire extinguishers.

The contract is being awarded in agreement with the US Federal Aviation Administration and the international Halon Replacement Working Group, consisting of representatives from aviation authorities, industry and airlines.

Help in the wider search for replacements for Halon 1211 and Halon 1301 (which is used as a fire suppressant in aircraft engines and baggage holds) will be provided by the test rig. Production of Halon ceased on 31 December, 1993, as the substance is an ozone depletant.

The CAA is keen to retain the fire-fighting qualities of Halon 1211, particularly its property of initially streaming as a liquid before turning to vapour. That characteristic makes it particularly useful in dealing with hidden fires, such as those beneath the cabin floor, where the only access for the agent is through ventilation grille. The CAA hopes to begin testing of 1211 replacements by the middle of this year.

Meanwhile, the search for a Halon 1301 replacement is now focusing on two distinct areas of research. The FAA and the CAA are establishing a protocol to set the safety levels which need to be attained by a 1301 replacement for aircraft holds.

Work on finding a replacement for Halon 1301 in aircraft engines is being driven by military research, particularly in the USA on the Lockheed/Boeing F-22 programme, which has funding allocated to search for suitable alternatives.

Source: Flight International