In short: the transport prosecutor's office issued a penalty for launching a copter in a residential area. Article - Part 2, Article 11.4 of the Administrative Code of the Russian Federation "Violation of the rules for the use of airspace". They write that for such a flight it is necessary to request permission to use the airspace and in general created a threat to the safety of the movement of aircraft.
Well what can I say. On the one hand, there is some reason for this. If we ignore all the details of the implementation, then the copter may be trivial to fall on someone's head. This situation is advisable to warn. But the line between adequate application of the law and inadequate is very thin. So you can screw and kids with paper airplanes. It would be interesting to learn the regulation of such small flying technology in other countries.