All structures repair themselves to 50% life. All structure fires are automatically put out.
This all-in-one safety system automatically dispatches robotic drones to put out any fires and perform basic repairs on damaged structures. Although these drones are effective at doing basic repairs, they do not have a strong enough AI to perform the more delicate repairs needed to restore a structure past 50% structural integrity.
The StarCraft II engineering bay was designed to be a more simple structure than its predecessor. It was decided to make it a grounded structure as per the belief that only unit-producing structures should be able to lift off.