Sunfish
At the risk of squandering what little credibility I have by posting on this thread, I need to explain something to some of you....
The fact that someone can make a "Test flight" and return the aircraft in one piece after exposure to some level of volcanic ash proves absolutely nothing. Detailed examination of the hot section of the engine is required, probably right down to the microscopic level and including sectioning of first stage turbine blades and nozzle guide vanes to check the cooling passages for contamination.
I'm not sure what turbine blade life is these days, but it must be of the order of at least 6000 hours plus, and probably well over 10,000 engine hours. If volcanic ash contamination compromises the figures for blade life in the slightest then airlines cannot fly because they are buying themselves a simply massive maintenance cost increase in the future. Furthermore, there would not be enough blade and vane manufacturing capacity available to satisfy demand.
To put it another way, I can take the air filter off my car and still run it up and down the road today and nothing will happen, however I would be wrong to conclude from that experiment that the provision of air filters by the car manufacturer was unnecessary overkill designed merely to boost profits.
To put it another way, If the engines will get their lives shortened by dust contamination, then the aircraft cannot fly, at least not at todays ticket prices anyway.
This is a long term business consideration in decision making and not a short term concern to salvaging your current customer base
To put it another way, the operators already make decisions like this on a real time basis everyday.
Perhaps we can revisit this months from now.