As the title says, it is really terrible to have Maintenance Drones suddenly go up in an oily explosion just because they left the Z-Level. So my suggestion is that they should be allowed to leave the Station Z-level. It can be very helpful, especially when it comes to maintaining the Outposts and the Telecomms Satellite. If maintenance drones try to leave with the CT shuttle, they can be warned, just like robots, that it is not allowed to do so, except during emergencies.