I am a commercial multi-engine pilot with instrument rating. I have a current medical and BFR. I have previously received training in a specific turbojet aircraft (SIC) but am not current. Here are my questions: 1. For Part 91 flight operations what do I need to be current and qualified as a Second-in-command in this turbojet aircraft type? 2. If I am current in a complex multi-engine aircraft already what do I need to be qualified in the turbojet aircraft? 3. If all I need is (3) take-offs and landings while flying with a current qualified PIC in the aircraft and a mechanic is onboard, does he count as a crewmember (not required) or a passenger?