Can my mechanic rig a jetpack on his combat drone if he takes the armor slot mod for it?
Armor slot doesn't have anything specifying what armor mods can go in it. Jetpack is an armor mod. So I first though "why wouldn't you be able to?"
Ah... the "can install only in light or heavy armor stipulation." Armor Slot doesn't say anything about considering the drone to be a certain class of armor, either. So, technically no.
It should probably be allowed, but in SFS you might find someone dinging you on the technicality. That said, I'm not sure there are too many GMs digging that far into the weeds when you show up with a jetpack drone.