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 can include Rocket engine, rocket, Pump-jet, water jet, and ...
or other
turbine engine
A gas turbine, also called a combustion turbine, is a type of continuous flow internal combustion engine. The main parts common to all gas turbine engines form the power-producing part (known as the gas generator or core) and are, in the direct ...
due to the extinction of the flame in its
combustor. The loss of flame can have a variety of causes, such as
fuel starvation, 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 of ...
,
foreign object damage
In aviation and aerospace, foreign object debris (FOD), is any particle or substance, alien to an aircraft or system, which could potentially cause damage.
External FOD hazards include bird strikes, hail, ice, sandstorms, ash-clouds or obje ...
deriving from
birds
Birds are a group of warm-blooded vertebrates constituting the class Aves (), characterised by feathers, toothless beaked jaws, the laying of hard-shelled eggs, a high metabolic rate, a four-chambered heart, and a strong yet lightweigh ...
,
hail
Hail is a form of solid 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 hailstone. Ice pellets generally fal ...
, or
volcanic ash
Volcanic ash consists of fragments of rock, mineral crystals, and volcanic glass, created during volcanic eruptions and measuring less than 2 mm (0.079 inches) in diameter. The term volcanic ash is also often loosely used to refer ...
, severe
precipitation
In meteorology, precipitation is any product of the condensation of atmospheric water vapor that falls under gravitational pull from clouds. The main forms of precipitation include drizzle, rain, sleet, snow, ice pellets, graupel and hail. ...
, 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 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 a 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
In aerodynamics, the flight envelope, service envelope, or performance envelope of an aircraft or spacecraft refers to the capabilities of a design in terms of airspeed and load factor or atmospheric density, often simplified to altitude. The ...
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, first flew on 22 February 1987, and was introduced in April 1988 by Air France.
The first member of the fam ...
passenger jet has a maximum
ceiling
A ceiling is an overhead interior surface 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 ...
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.
can make restart impossible.
References
{{Authority control
Aviation risks
Jet engines