............ and in addition to CRAN's remarks. :) :) :)
My knowledge about helicopters is very limited, but one thing became very obvious, very quickly. There are two extremes in the rotorcraft industry.
One lunch-hour, while auditing a helicopter maintenance course, I was taking some dimensions and had placed a single sheet of paper on top of an engine. An engine, with display cutouts, that would never fly again. An instructor happened to be passing by and he reamed my ass out for what seemed like an hour, for laying something on an engine.
At the other extreme, there have been gyrocopter get-togethers at someone's farm. The farm owners keep their gyros in a shed, along with the antiquated tractor and plow. The most popular metal in these sheds was iron oxide.
Professional pilots are very fortunate to be backed up by other professionals on the ground.