Sand storm V Volcanic Ash
@loc22550
I can directly answer your question about sand storms v volcanic ash.
Sand (in its many forms) really has only effect on the engine. Abrasion.
Volcanic Ash is 'harder' than sand, and has sharper edges therefore dramatically increasing the abrasive properties of the particles. Over time, this abrasion will render an engine U/S. How much time? we don't know yet hence the problem.
The bigger problem with the Volc. Ash, is that it melts inside the combustion chamber turning to a fluid. When it cools, it forms on the surfaces of the engine causing blockages of cooling holes and veins, imbalancing of rotating parts etc.
Since the turbine engines operating temperatures reach far beyond the melting point of metal components within the engine, when these cooling holes and veins are blocked, the engine fails soon thereafter.
You don't get this problem with a sandstorm.
In Germany, we have the airspace open above FL355. no one has used it yet and sadly i think more of the same tomorrow and tuesday too.
Lets all just hope, and pray if you are so inclined that this disaster is over sooner rather than any kind of later.