Hey Jaba, I think you touched on something worth noting when you say,
Quote: " typically on a dusty old C172 "
I have worked on aircraft that live central Aus, and the dry climate does play a part in the longevity of such, think Arizona. I picked up a 182 from central Aus, not internally primed (typical and maybe a little unique for Australia more so than other places due to saving a couple grand when ordering from the factory in the 70's-80's, but that's another story) and it was like a coke can inside, absolutely pristine, now it lives on the coast any surface not inhibited was quickly corroding.
Jas24, Typically when you file a blade, personally I come from a minimalist point of view, it is difficult to know how much material has been removed, and considering most of the damage is toward the tip where the centrifugal forces are at most play, has the most effect on balance, and will very quickly go out of balance, yes we do dynamically balance props, but sending a fixed pitch to the shop allows them to measure at incremental stages the remaining chord and statically balance also, along with check blade angles etc.
You would think blade angles wouldn't change much but it is not uncommon to find when trouble shooting an imbalance a blade out by more than half a degree at the tip which is significant.
Whilst a blanket change to AD/Prop/1 to Service/Overhaul in accordance with the manufacturers Data (i.e. 6Yr) may seem counter productive at times, I think the incorporation of a geographically guiding covenant would be appropriate.
Ultra, Solid.