Complex sentence: Around 1970, Powell found work as a roadie for the band Lynyrd Skynyrd and remained a member of the Skynyrd crew for two years, during which the band secured a support role for Mountain.
Split into simpler sentences: Around 1970, Powell found work as a roadie for the band Lynyrd Skynyrd. Billy remained a member of the Skynyrd crew for two years, during which the band secured a support role for Mountain.