Take a good look in your engine maint manuals. This is from PWC.
J. Aircraft Flown through Volcanic Ash or Smoke.
(1) Do a compressor wash - performance recovery (Ref. Chapter 71-00-00, POWER
PLANT - CLEANING).
(2) Drain and refill the engine oil system (Ref. Chapter 72-00-00, ENGINE GENERALSERVICING).
(3) Replace the oil filter (Ref. Chapter 79-21-00, OIL SYSTEM (DISTRIBUTION)-
MAINTENANCE PRACTICE).
(4) Do a function check of the chip detector (Ref. Chapter 72-00-00, ENGINE
GENERAL-SERVICING).
(5) Inspect the compressor for damage (Ref. Chapter 72-00-00, ENGINE
GENERAL-INSPECTION).
(6) Do a power assurance check as per the Applicable Aircraft Manual.
(7) Drain and refill the engine oil system with new oil after 50 ±10 hour (Ref. Chapter
72-00-00, ENGINE GENERAL-SERVICING).