Rotor with Rotor Subgrids
This happens with large-grid construction (I didn't check small-grid construction):
1. Place an armor block.
2. Attach a small reactor, battery, or solar panel for power.
3. Attach a rotor (standard or advanced).
4. Attach an armor block (or conveyor junction if an advanced rotor) to the rotor head.
5. Attach a rotor (standard or advanced) to each of the four faces of the armor block, radially oriented.
6. Using copy/paste so the attached subgrids are identical, attach a structure, such as a contrived fan blade, to three of the rotors (see the first attached picture).
7. Again, using copy/paste so the attached subgrid is identical, attach the last structure to the fourth rotor (see the second attached picture).
Most of the time the structure immediately flies apart. If not, attach an armor block to any of the four subgrid structures and that'll trigger the event.