All firebombing aircraft in the CFS fleet have the ability to drop water with aerial firefighting product additives. Aerial Firefighting Products (also referred to as suppression chemical additives) are added to water to increase the effectiveness of firebombing drops, and may be divided into three (3) classes: foam suppressants, water enhancers and long term retardants.
CFS will only use products that have been approved by the United States Department of Agriculture (USDA). The USDA maintains a highly specialised, comprehensive laboratory and field testing program (the "Wildland Fire Chemical System"), which tests products for human and environmental toxicity, handling safety, biodegradability, corrosion of aircraft components, and effectiveness prior to their qualification and approval for use.
CFS uses a range of approved and commercially available products within each of the three classes.
Fire Suppressant Foam
Fire suppressant foams are a combination of wetting, foaming and surfactant agents (commonly used in shampoos and detergents), added to water to improve its effectiveness through increased retention on vegetation fuel surfaces and reduced evaporation. Foam is used to "knock down" a fires intensity to allow ground resources access to the fire edge for extinguishment.
The Erickson Air-crane dropping foam
Water enhancers (often referred to as "Gels") increase the viscosity, adherence ability, cooling time and wetting capability of water dropped onto vegetation by aircraft. These products can also improve firebombing drop accuracy through reduced wind drift. Water enhancers are used for direct attack to "knock down" a fire as an alternative to foam, and are particularly effective in scrub or forest vegetation.
Long-term retardants contain mineral salts that inhibit the vegetation's ability to ignite, and are designed to be laid on fuels ahead of a fire in order to reduce or halt fire spread. Retardants remain effective even after the water in the mixture has evaporated, but are ineffective if a fire is "spotting". The red colouring in the product (an iron oxide colorant) allows pilots to see drops on vegetation from the air and will eventually wash away after rain or break down over time with UV light exposure.
For additional information on all types of products used by CFS from aerial firefighting aircraft, see the Aerial Firefighting Products Fact Sheet.