flameout
{{Redirect|Flame out|Internet usage|Flaming (Internet)}}
{{Short description|Type of engine issue in aviation}}
{{Use dmy dates|date=August 2014}}
In aviation, a flameout (or flame-out) is the run-down of a jet engine or other turbine engine due to the extinguishment of the flame in its combustor. The loss of flame can have a variety of causes, such as fuel starvation, excessive altitude, compressor stall, foreign object damage deriving from birds, hail, or volcanic ash, severe precipitation, mechanical failure, or very low ambient temperatures.{{cite web |url=http://www.newton.dep.anl.gov/askasci/eng99/eng99236.htm |title=Turbo Jet Flame Out by Ask a Scientist |date=2003 |publisher=Argone National Laboratory |access-date=2012-03-25 |url-status=dead |archive-url=https://web.archive.org/web/20150228171438/http://www.newton.dep.anl.gov/askasci/eng99/eng99236.htm |archive-date=2015-02-28}}{{cite magazine |last=Garrison |first=Peter |date=1 September 2006 |title=Flameout: Why the fire in a perfectly healthy jet engine can die |magazine=Air & Space Magazine |url=https://www.airspacemag.com/flight-today/flameout-9043856/ |access-date=2012-03-25}}
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 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.{{cite web |url=https://www.faa.gov/aircraft/air_cert/design_approvals/engine_prop/media/engine_malf_famil.doc |format=doc |title=Airplane Turbofan Engine Operation and Malfunctions, Basic Familiarization for Flight Crews |publisher=FAA |access-date=2012-03-25 |url-status=live |archive-url=https://web.archive.org/web/20130904032524/http://www.faa.gov/aircraft/air_cert/design_approvals/engine_prop/media/engine_malf_famil.doc |archive-date=4 September 2013}}
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."Gas Turbine Performance". 2nd edition. P.P.Walsh P. Fletcher. {{ISBN|0-632-06434-X}} p. 484
For example, the Airbus A320 passenger jet has a maximum ceiling of over {{cvt|39000|ft}}, but its certified engine relight envelope only extends to {{cvt|30000|ft}}. Up to that altitude, a windmill restart can be attempted at airspeeds greater than {{convert|260|kn}}; below that speed, a starter-assisted relight is required.{{cite book |title=A318/A319/A320/A321 Flight Crew Operating Manual |date=17 April 2017 |publisher=Airbus |page=PRO-ABN-ENG 13/106}}
Core lock can make restart impossible.
See also
References
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{{Aircraft gas turbine engine components}}
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