Hey, been working on some other sprites for this game..it's been awhile. But I have this massive helicopter sprite I'm working on, and I'm just kinda at a loss of what to do with the form...I am happy with the lineart but the actual shading part has been throwing me a curveball. I was hoping someone else more experienced might be able to help me out.

In the game, the rotors move indepently from the body, so I'm not sure how to handle the shading there, perhaps animation. This is with only four shades of gray..I plan on using 8 or 12 perhaps, we shall see. All C&C is welcome.
Thanks
Sokota