a fire zone u201c hot side u201d from a non fire zone u201c cool side u201d aviation regulations and other requirements mandate that hot air or other gases should not enter the non fire zone for example some components on the cool side are formed of composite materials that are not rated for high temperature exposure also due to weight considerations some components disposed on the cool side do not have insulation or other fire protection in some engine designs the control mechanism or fadec is disposed in a non fire zone in such designs the signal tube 20 extends from the combustor on the hot side to the control mechanism on the cool side under normal operating conditions the static fluid in the signal tube 20 is generally at ambient temperature if a break or other breach improper connections etc were to occur in the signal tube 20 the usually static fluid contained therein would leak to the surroundings and hot fluid air from the combustor would begin flowing in the tube and leaking through the breach if the break or other breach occurs in the non fire zone the leaking fluid would exceed allowable temperature requirements in current operating protocols if the engine control 14 or fadec does not receive a pressure signal due to a break or.