"Does the low rotor rpm warning horn sound before starting the engine? The check which I was tought was starting the engine first, and then while running up check if the low rotor rpm audio warning goes off at approximately 360 rpm."
BA & B2 you can press the "horn" button with the engine off and master electrical on, it should sound. Horn is muted (with button in) when hyd pressure > 30 bar & RPM < 250. And when RPM > 360 (& < 410 *B2*)