Definition
A flameout in a turbine engine caused by a fuel-air mixture that contains too little fuel to sustain combustion. When the mixture becomes leaner than the engine's lean combustion limit, the flame in the combustion chamber can no longer be maintained and the engine ceases to produce power.
Plain English
The fire inside a jet engine goes out because there isn't enough fuel mixed with the air to keep it burning.
Context Anchor
Seen in turbine engine operation, especially when discussing combustion, fuel flow, flameout, or engine relight procedures.
Derivation
Lean' refers to a fuel-air mixture with a low proportion of fuel relative to air. 'Blow out' describes the flame being extinguished, much as a candle is blown out. Together the term means the flame has been extinguished because the mixture became too lean to burn.
Why Pilots Care
Can cause sudden loss of engine power in flight, especially critical during climb or cruise in single-engine aircraft.
Analogy
It is like trying to keep a campfire burning with plenty of air but not enough fuel. The air is there, but the fire cannot continue without enough to burn.
Grounding Statement
A turbine engine needs the right balance of air and fuel; if the fuel side gets too low, the flame can stop.
Intuition Check
Lean does not mean efficient or healthy here. It means there is too little fuel in the air-fuel mix to keep the flame burning.
Example Sentence 1
The pilot pulled the throttle back too quickly during the descent and caused a lean blow out, requiring an in-flight engine restart.
Example Sentence 2
Proper fuel scheduling prevents lean blow out when operating near the engine's lean limit.