ovl_Boss_Fd (Flying Volvagia) is one of two actors that make up Volvagia. Specifically, this actor makes up the Volvagia that rises from underneath the ground and flies around the boss room, whereas ovl_Boss_Fd2 (Hole Vovlagia) is the actor that pops up out of the ground and attacks Link.
Flying Volvagia (0x0096) is used to spawn Hole Volvagia.
Debug Rom Notes
ROM - C9B530 - RAM - 22F630 - ADDIU - T4, R0, 0x012C - Timer for Volvagia's Flight in Flight form (240C012C) ROM - C9B4CC - RAM - 22F5CC - ADDIU - T6, R0, 0x0014 - Timer for Volvagia's preparation for diving and rising. (240E0014) ROM - C9B5E0 - RAM - 22F6E0 - ADDIU - T1, R0, 0x0096 - Timer for Volvagia's diving (24090096) ROM - C9B708 - RAM - 22F808 - ADDIU - T1, R0, 0x0032 - Timer for Volvagia's Emergence from hole (240D0032) ROM - C9D978 - RAM - 231A78 - ADDIU - T9, T8, 0xFFFE - Deal 2 Damage (Negative Hex) to Volvagia while in Flight Form. (2719FFFE) ROM - C9D98C - RAM - 231A8C - ANDI - T1, T0, 0x1000 - Is the Weapon Ice Arrows? (Refer to Damage Identifier Bytes) (31091000) ROM - C9D998 - RAM - 231A98 - ADDIU - T9, T8, 0xFFFE - Then deal an additional 2 Damage (Negative Hex) to Volvagia while in Flight Form. (272BFFFE) ROM - C9D9A4 - RAM - 231AA4 - ADDIU - T5, R0, 0x0002 - Amount of HP Volvagia recovers if he was to be killed while in the air. (240D0002)