In aviation, a flameout (or flame-out) is the run-down of a

jet engine A jet engine is a type of reaction engine, discharging a fast-moving jet (fluid), jet of heated gas (usually air) that generates thrust by jet propulsion. While this broad definition may include Rocket engine, rocket, Pump-jet, water jet, and ...

or other turbine engine due to the extinguishment of the flame in its

combustor A combustor is a component or area of a gas turbine, ramjet, or scramjet engine where combustion takes place. It is also known as a burner, burner can, combustion chamber or flame holder. In a gas turbine engine, the ''combustor'' or combustion ...

. The loss of flame can have a variety of causes, such as

fuel starvation In an internal combustion engine, fuel starvation is the failure of the fuel system to supply sufficient fuel to allow the engine to run properly, for example due to blockage, vapor lock, contamination by water, malfunction of the fuel pump or i ...

, excessive altitude,

compressor stall A compressor stall is a local disruption of the airflow in the compressor of a gas turbine or turbocharger. A stall that results in the complete disruption of the airflow through the compressor is referred to as a compressor surge. The severity o ...

, foreign object damage deriving from

birds Birds are a group of warm-blooded vertebrates constituting the class (biology), class Aves (), characterised by feathers, toothless beaked jaws, the Oviparity, laying of Eggshell, hard-shelled eggs, a high Metabolism, metabolic rate, a fou ...

hail Hail is a form of solid Precipitation (meteorology), precipitation. It is distinct from ice pellets (American English "sleet"), though the two are often confused. It consists of balls or irregular lumps of ice, each of which is called a hailsto ...

, or

volcanic ash Volcanic ash consists of fragments of rock, mineral crystals, and volcanic glass, produced during volcanic eruptions and measuring less than 2 mm (0.079 inches) in diameter. The term volcanic ash is also often loosely used to r ...

, severe

precipitation In meteorology, precipitation is any product of the condensation of atmospheric water vapor that falls from clouds due to gravitational pull. The main forms of precipitation include drizzle, rain, rain and snow mixed ("sleet" in Commonwe ...

, mechanical failure, or very low ambient temperatures.

Engine control

Early jet engines were prone to flameout following disturbances of inlet airflow, or sudden or inappropriate

thrust lever Thrust levers or throttle levers are found in the cockpit of aircraft, and are used by the Pilot in command, pilot, copilot, flight engineer, or autopilot to control the thrust output of the aircraft's aircraft engine, engines, by controlling th ...

movements, which resulted in incorrect air-fuel ratios in the combustion chamber. Modern engines are much more robust in this respect, and are often digitally controlled, which allows for significantly more effective control of all engine parameters to prevent flameouts and even initiate an automatic restart if a flameout occurs. Flameouts occur most frequently at intermediate or low power settings such as in cruise and descent. To prevent a flameout when atmospheric or operational conditions are conducive to it, engine control systems usually provide a continuous ignition function. Ignitors are normally used only at engine start, until the flame in the combustion chamber becomes self-sustaining. With continuous ignition, instead, the ignitors are continually sparked every second or less, so that if a flameout occurs, combustion can immediately be restored.

Engine restart

Following a flameout, jet engines can normally be restarted in flight, provided the aircraft is flying within the portion of its flight envelope defined as the ''engine relight envelope''. Depending on where in the relight envelope the restart is attempted (that is depending on the aircraft's airspeed and altitude), the procedure may simply rely on the airflow (''windmill restart'') or require the use of the starter (''starter-assisted restart'') in order for the compressor to achieve sufficient rotational speed for successful ignition. For example, the

Airbus A320 The Airbus A320 family is a series of narrow-body airliners developed and produced by Airbus. The A320 was launched in March 1984, Maiden flight, first flew on 22 February 1987, and was introduced in April 1988 by Air France. The first membe ...

passenger jet has a maximum

ceiling A ceiling is an overhead interior roof that covers the upper limits of a room. It is not generally considered a structural element, but a finished surface concealing the underside of the roof structure or the floor of a story above. Ceilings can ...

of over , but its certified engine relight envelope only extends to . Up to that altitude, a windmill restart can be attempted at airspeeds greater than ; below that speed, a starter-assisted relight is required. Core lock can make restart impossible.

References

{{Authority control Aviation risks Jet engines

Engine control

Engine restart

See also

References