Huey skid tubes
Bristow used to run a training school at Galehmorgi in southern Teheran for the Iranian Military in the early 70's.
The UH-1H's used to practice EOL's on a strip to the south and would get through a set of skid tubes in 2-3 days until the Chief Engineer (john Snow) came up with the idea of reinforcing the shoes.
New shoes were fitted to a pair of old tubes and then taken to a local welding shop where they would be built up with 10mm of weld; Stellite from memory and that resulted in much improved life.
Tail rotors used to cop a lot of stone damage and the solution there was to fill up the dents/holes with Metalset A4 last thing at night. Part of the preflight inspection by engineers the following morning would involve sanding the filler down to a smooth profile and off she went.
Pilots didn't like this one little bit but flew anyway; I never heard of any blades failing so proving what a great machine the 205/ Huey was!