Complex sentence: HFF's aircraft have been fully restored to flying condition, and fly regularly at monthly summer Fly Days (1), HFF's September Vintage Aircraft Weekend (2), and Paine Field's Aviation Day (3) in May.
Split into simpler sentences: HFF's aircraft have been fully restored to flying condition, and fly regularly at monthly summer Fly Days 1. Historic Flight Foundation, HFF's September Vintage Aircraft Weekend (2), and Paine Field's Aviation Day (3) in May.