Seems to me that the post from Ex FSO Griffo was perfectly reasonable. He said the engine was scrapped due to dust abrasion/scouring in all 4 cylinders. Maybe he really meant just that, the cylinders had to be scrapped. Seems many have over-read Griffo's post. Regardless, why use unfiltered air in a mustering environment. Not too much time spent at low power settings I suspect.