OT : Volcanic Ash Cloud

[Karlos Santos]

Ok back on topic:

[diezdiazgiant]

Not quite. The granulate is nasty stuff, hard and destructive. The way a turbine engine works, the compression fan outer tips run close to the outer walls of the engine at very high speeds (in fact the outer walls are wear strips that are designed to maintain minimum gap to the fans). In the volcanic ash, the fans work like sand blasters to the wear strips and other internal engine components wearing them out extremely quickly (minutes). Ounce the engine can no longer compress the air sufficiently, the burner runs out of oxygen and a "flame out" occurs. And as the engine is now worn out, it can no longer be re-lit. Game over.

Volcanic ash and water contamination are two of the biggest contributors to total engine loss in commercial aviation and it is taken VERY seriously. I currently work in aerospace and am finishing the certification of a flight control system, where this failure mechanism is clearly written in the regulations as one we have to cater for.

All that said, how much is too much? We can only err on the conservative side. Hence ground all of Europe.

But my weekend plans are still upset by no MotoGP...

Phil.

yeah it was just a gross simplification at work i had heard, i was under the impression that what would cause the engine to seize is that the granulate would get in the crevices of finer mechanical workings and restrict its ability to move. like sand in a gun. but the sand blaster effect makes sense too