A jet engine tailpipe fire, also referred to as an internal fire, is one which occurs within the normal gas flow path of the engine. A tailpipe fire will only occur on the ground and only during engine start or during engine shutdown. It is difficult for the flight deck crew to identify a tailpipe fire as its location within the engine core will not result in activation of engine fire warning systems. Flight deck indications are limited to the potential of an abnormal rise in exhaust gas temperature (EGT), turbine inlet temperature (TIT) or interstage turbine temperature (ITT) as appropriate to the aircraft in question.
A tailpipe fire is caused by an excess of fuel in the combustion chamber, the turbine or the exhaust nozzle that ignites. It can result in significant flames coming out of the engine exhaust or in smoke from either the exhaust or engine inlet. Although a tailpipe fire can be very dramatic, it rarely results in engine damage as it occurs in a part of the engine that is designed for very high temperatures. However, it is possible that the flames from a significant tailpipe fire could damage other aircraft components such as the flaps.
Tailpipe fires are most often visually identified by ground crew, ATC or cabin crew and reported to the flight deck crew as an engine fire. This often results in the crew incorrectly applying the engine fire procedure instead of the tailpipe fire procedure. In the event of a tailpipe fire, the flight crew should
- abort the start (or continue with the shutdown) to stop the flow of fuel to the engine
- dry crank the engine to extinguish the flames and remove the remaining fuel from the engine
Following the engine fire drill will have no effect as the fire agent is discharged outside of the engine core. Additionally, activation of the engine fire emergency sequence may negate the ability to dry crank the engine.
Unless a dry crank is not possible due to lack of a bleed air source or other reason, ground assistance to extinguish the fire is not usually necessary. Rescue and Fire Fighting Services intervention should only occur as a last resort due to the potential of corrosive damage to the engine that can be caused by fire extinguishing agents.