Just made this old fellow (#8412). Found a box of my old technic lego and still had the book inside. It's complete expect for 1 black piece I had to replace with
A brief look at LEGO Technic helicopters through the years
Lego 8640 Polar Copter - Lego Technic set for sale best price
LEGO® Technic™ Airbus H175 Rescue Helicopter 42145 Model Building Kit (2,001 Pieces)