I think you're out of luck there;
the Let 410 was never certified in the US by the FAA. I did a search on the FAA website and I could not find a Type Certificate Data Sheet.
Apperently the 420 was certified by the FAA in 1998 but according to these guys there are no US operators:
Why some LET -410 airplanes are not allowed by the FAA to fly in the U.S territory