C of G
could change - if you moved the helicopter from one end of the box to the other, but the total weight on both scales wouldn't.
If you entered autorotation or did a low-G pushover, for a moment the box would show less weight.
If you flew long enough, the box would show less total weight, as some of the mass of your fuel would have been converted into energy (heat and noise). Probably wouldn't be able to measure it on a bathroom scale though.
What if the box were on the back of a truck and you drove it through a TFR while hovering the helicopter inside the box? Is it a bust?
