Compressor stalls are a leading cause for emergency shutdowns on gas turbine engines. Here's how it happens...
1) Airflow normally moves uniformly through a jet engine. When it's disrupted or distorted as it enters the engine, there's a high risk for a compressor stall.
2) The most common reasons for disrupted air entering the engine are: foreign object damage (like a bird strike), worn or dirty compressor components, in-flight icing, operations outside the design envelope, and improper engine handling.
3) Air separation and stalls inside the engine occur at a blade's critical angle of attack, just like on the wing of your plane. Disrupted, turbulent airflow follows this airflow separation around the blades, entering the engine.
4) This turbulent airflow entering a turbine engine is bad news. The ratio of air to the set RPM is now incompatible.
5) Just because you see a flame doesn't mean the engine is on fire. When the airflow is disrupted, there's an excess of fuel compared to the amount of air required. This excess fuel is burning off when you see flames.
6) Compressor stalls are serious business, because they can either result in short, rapid loss of compressor performance or engine surging and complete loss of compression.
7) In the case of US Airways Flight 1549, multiple bird strikes damaged both engines on the Airbus A320, causing compressor stalls and engine failures.
