As I mentioned previously, a Wessex which broke a tie-down on a power run took ages for a directed jet of foam to stop the engine: a matter of 5-10 minutes. The pilot was unconscious, the Wessex on its side, stationary, with all blades broken at the root, and the Gazelle engine valiantly flogging away despite a stream of foam straight into the intake. Admittedly many, many years ago with firefighting equipment unequal to the stuff we have now but a blanket 'area attack' foam may or may not have achieved much in the way of starving the engine or the occupants of oxygen. Especially given the movement of the Squirrel and the associated engine intake.