Shy torque,
I learn each time I log onto pprune!
There are differences between rotor blades, but the Sikorsky family uses nickel strips, as does Boeing on their family, at least according to the web sites I found about 5 minutes ago. The Bell 430 uses nickel caps on its steel strips, so the actual impact surface is nickel, I think. Perhaps it is that way for the other newer design Bell baldes.
I must say that I don't know if the spark response different than other helos, I hope ppruners can help out. We can guess that CH-47, Bell 430 and H-60's are the same. Are they in reality?
Anyone with specific knowledge of different spark response (under goggles and not), with different helo types under the same operating environment?