A mechanic changed an airplane in a way that may change its flight characteristics. What must happen before the airplane carries passengers?

1. 1A rated pilot makes and logs an operational check flight
2. 2The owner signs a release for each passenger
3. 3An FAA inspector approves the next flight in writing first
4. 4The airplane flies five hours with only crewmembers on board

Source: 14 CFR Part 91, § 91.407 Operation after maintenance, preventive maintenance, rebuilding, or alteration.