The Sky Fortress Add-on for Just Cause 3 has 7 achievements worth 225 gamerscore.
Use the Bavarium Wingsuit to take off from water.
Use the Barrel Roll to evade 10 incoming missiles.
Beat the last mission of the Sky Fortress Expansion and complete the story arc.
Defeat the "Old Friend" (Boss at the end of "Taking Control").
Defeat 1 of each Drone type.
Earn at least 1 Gear in all Challenges of the Sky Fortress Expansion.
Earn 5 Gears in all Challenges of the Sky Fortress Expansion.