Flameout

A flameout refers to the failure of a jet engine caused by the extinction of the flame in the combustion chamber. It can be caused by a number of factors, including fuel exhaustion; compressor stall; insufficient oxygen supply; foreign object damage (such as birds, hail or even volcanic ash); severe inclement weather; and mechanical failure.

Description

Flameouts occur most frequently when the engine is at an intermediate or low power setting (such as during the cruise and descent phases of flight). Most of the time, they are recovered from uneventfully. To recover from a flameout, the pilot should ensure the engine's fuel supply has been restored and then simply perform an engine restart as detailed in the aircraft's Flight Operations Manual.

Early jet engines, such as Junkers Jumo 004 used in early German jets, including the Messerschmitt Me 262, were at relatively high risk of flameout. Fast acceleration or inappropriate throttle settings could impoverish the fuel/air mixture causing a flameout. If this happened at low altitude, it would often lead to the total loss of the aircraft. However, modern jets are engineered to a higher degree of technical quality and are controlled by systems (FADEC) that constantly fine-tune their performance; as such flameouts are not such a risk as they were in the early days of jet-powered aviation.

Windmill restart

A way to try and restart an engine that has experienced a flameout is by using a procedure called a windmill restart; this is a maneuver that uses the kinetic energy of the aircraft to attempt to restart the engine. The procedure is designed to force air into the engine housing to spin the rotors and create enough pneumatic pressure for ignition. Typically in jet aircraft, to achieve the needed compression, airspeed of at least 300 knots (560 km/h; 350 mph) is required, at which point the engine may be able to restart. However, due to the significant loss of altitude required for the procedure, it is generally deemed a last resort.

Notable incidents of flameout

See also: Fuel starvation#Fuel exhaustion and starvation incidents on aircraft

• On 6th August 1945 the top USAAF fighter ace Richard Bong lost his life in a flight accident as his Lockheed P-80 Shooting Star fighter suffered a flame out and dived to ground.

• In June 1972, Jean Boulet piloted an Aérospatiale Lama helicopter to an absolute altitude record of 12,442 meters (40,814 ft) [1]. At the extreme altitude the engine flamed out. The helicopter landed safely after the longest ever autorotation in history.

• In a huge hailstorm in 1977, Southern Airways 242, a DC-9, lost both engines due to the hail. The plane landed on a highway and crashed into a gas station, killing 72.

• In 1982, British Airways Flight 9 suffered flameouts in all four of its engines after flying through a cloud of pyroclastic material thrown up by the eruption of Mount Galunggung. The pilots were eventually able to restart three of the engines and make a safe landing.

• On 21 November 2002, during a routine test flight the Eurofighter DA6, a Spanish development prototype, crashed following an irrecoverable ‘double engine flame-out’ in flight; both crew members escaped unharmed.

• In 2004, Pinnacle Airlines Flight 3701 suffered flameouts in both of its engines. The aircraft crashed near Jefferson City, Missouri after being unable to restart the engines. The pilot and co-pilot were both killed.

• In September 2007, while engaged in separation tests of the GBU-39 Small Diameter Bomb, an F-22 Raptor suffered a brief dual-engine flameout while performing a negative-g, 360 degree roll with eight SDBs loaded in the weapons bay. The flameout occurred because the aircraft entered the maneuver with an incorrect trim setting. The engines were restarted almost immediately, allowing the pilot to remain in control of the aircraft and land at Edwards AFB, California, without further incident.