I tried to squeeze some info out of Cessna and Pratt, but no real new stuff there. No guidelines, no ash concentration or anything
The MM for our P&W306C says:
9. Aircraft Flown Through a Cloud of Volcanic Ash
A. Procedure
(1) Do a compressor and turbine wash (Ref. 71-00-00, CLEANING).
(2) Drain and refill oil system with new oil (Ref. 72-00-00, SERVICING).
(3) Replace oil filter (Ref. 72-00-00, SERVICING).
(4) Do a boroscope inspection of the compressor (Ref. 72-00-00, INSPECTION).
(5) Do a boroscope inspection of the HP turbines (Ref. 72-00-00, INSPECTION) and check for glass-like deposits on turbine blades.
If found, do a hot section inspection.
(6) Return engine to service if no unsatisfactory conditions are found.
(7) Drain and refill oil system with new oil (Ref. 72-00-00, SERVICING),
50 +/-10 flight hours after original oil change done at step 2.
I venture a guess, its about the same for all jet/TP engines. There is no definition of "ash cloud" though.
I just wonder what the boss says IF weŽd catch same Ash and weŽll be grounded for 2 HSIŽs way before they are due in normal ops...
When they lift the ban with particles still in the air, then the ball is in our garden and I frankly have no experience whatsoever with that stuff. Annoying to say the least.