Groove o' the day: Airto's samba in 3

Here's a favorite piece of drumming by Airto, from Chick Corea's Return to Forever album on ECM. I'd like to transcribe this entire track, but today I just have the primary grooves for you. The tune is a samba in 3; I've written it in 3/2, but it could also be counted in 6/4 or as 16th notes in 3/4. The intro, and various other points in the tune keeps a simpler bass drum part, buzzing the snare drum accent on 2:

As it develops, he also uses the standard samba pattern on the bass drum, and plays the snare accent as a stronger rim shot:

Get Return to Forever by Chick Corea

YouTube audio after the break: