Good information. One thought - if you're talking to ATC use full N-number, obviously. But when on a non-towered CTAF why not keep the call signs a bit simpler so that the brain is processing the information being said, instead of trying to remember a complicated call sign... eg, use "Helicopter Echo Fox." Or even use “Red Helicopter” as the call sign so other traffic can affirm what they’re looking for. What say you?