[holding answer 21 April 2008]: Explosion suppressant foam is one of several fuel tank inerting systems available to prevent fuel tank explosion. An alternative inerting system is the on board inert gas generation system (OBIGGS), such as that fitted as standard to C-17s.
All but one of our A400M aircraft will, during manufacture, will be fitted with the necessary equipment to enable fuel tank inerting to be installed. The one exception to this is an early development aircraft which is already under construction and cannot be fitted with the enabling pipework for fuel tank inerting during its production. We are currently looking at ways to address this shortfall.