It's unclear how the various levels of drone AI and the Skill Unit ability work. I can read it a couple of ways:
1. Does the Skill Unit is only specify a skill that can be used under Limited, Expert, or True AI? If so, you can't tell a drone to "fix the ship" and go off on an away mission since it would stop working once you go out of range unless it has True AI.
2. Does the Skill Unit specify a skill that the drone can use completely without direction? If so, it can fix stuff while you're on away missions. That also implies that it can take actions on its own related to those skills.