Not true of all helicopters.
Can depend in which way round the Main Rotor blades are travelling. Tail rotor - Main Rotor Thrust coupling in a anti-clockwise direction of the main rotor, when viewed from above, will give a left skid low position, so putting the pilot (
on their own) in the left seat would mean the Lateral Centre of gravity who exceed limits. By putting the
solo pilot on the Right seat you even up the Lateral C of G.
H3
