Here is something I received today from a former neighbor this evening, thought it might interest some of you.

Cheers!
Bill

This is an interesting photo of a very rare event in today's world. The photographer was very lucky to catch this because the fire in the engine inlet resides there for only about a 1/20th of a second for each surge cycle. This is more than an engine fire as the title implies.

This is typical of a low pressure compressor surge (backfire) where there are 1 to 3 successive "cannon shots" of fire balls spaced about 3/4 a second apart. This means the engine is operating in excess of 160,000 Horsepower and 1/40th of a second later all the Mach .70+ airflow reverses direction from inside the engine. It projects a fireball from the power generating core combustor of the engine out the front of the engine (surge phase). That fire ball is driven back into the engine (the point of this photo at about 1/3 of a second into the event cycle) by the forward speed of the aircraft and the residual inertia of the rotating fan. The airflow tries to re-establish normal direction in the engine at this point due to the rotating inertia of the engine rotors (recovery phase). Pratt & Rolls (this is a Rolls) engines may recover and operate at a reduced power level at this point.

But...

If the engine has been damaged too much (e.g. broken blades & parts particularly light built GE engines), the airflow will not resume a normal path and the engine disintegrates. If the engine is only partially damaged, it will give you 1 or 2 more cannon shots 3/4 seconds apart before the engine completely disintegrates. Either path the engine takes, that is the almost complete loss of a $12M engine and a guaranteed sweeping job for the runway. The occupants seated next to the failed engine will be temporarily deaf in one ear and all the other cabin occupants will complain of ringing ears. The pilot will think the controls have "whip sawed" him as the forces of the airplane are redistributed and then he forces them back to where they should be. Looking from behind or in front of the airplane, it will appear to "swerve" to the airplane's left, dip the nose down and then slowly lumber into the air at a shallow angle on the remaining engine. With all of the messed up airflow paths, the ECS system will receive a big slug of raw fuel, partially burnt fuel & parts from the bleed system. The cabin will fill with a haze from the contaminated hot bleed air.

Typical causes of this event are ingestion of a very large bird or object, thrown fan blade, bad engine control commands from the computer, a poorly maintained engine or an engine that has simply Worn out.