Erickson Aircrane is a classy act, in this day and age of squeezing royalties out of any stone found, Erickson's management has decided to be reasonable.
They have added a model page to their company website with a very reasonable royalty arrangement which basically comes down to do your best to represent the aircraft and they won't demand royalties.
They have a nice selection of drawings and photos to assist model builders.
http://www.ericksonaircrane.com/modelerzone.asp
I hope one of the model companies picks up on this, it would be nice to see a new S-64 since I understand the R-G kit has a lot of issues.