Originally Posted by
brooksjg
Err - no. The (now very old) USGS report on Pinatubo includes several notes about aircraft damage found well AFTER flights that could have caused it! The authors commented that the reason that there's no location given for some of the tabulated incidents is that no-one knew where they happened!
Some perspective on this. The only incident where there is no indication the crew knew about the ash at the time is
Originally Posted by USGC incident 91-14
Indications that aircraft flew through volcanic ash cloud were apparent only after aircraft underwent ground inspection in Kuala Lumpur, which revealed abrasion of plexiglass landing light covers and navigation lights, which were totally opaque. Cowling intakes were abraded and rough to the touch, while compressor blades were remarkably clean. Landing gear bays were covered in ash with ash sticking to oily surfaces. No apparent damage to windshields
There is very little additional information on this flight (not even who the operator was) so unclear if this was CAVU damage, night or IMC.
USCG to make the point that for several years there were issues with window and paint degrading and sulphate build up in hot sections for aircraft effected by the gas cloud (which was across the whole of the Northern Hemisphere).