Final answer:
A pilot, acting as second in command, remains current for 6 calendar months after successfully completing the instrument competency check specified in FAR Part 61, if no further IFR flights are made.
Step-by-step explanation:
In order to remain current, a pilot, acting as second in command, must undergo regular instrument competency checks as specified in FAR Part 61, which is the Federal Aviation Regulation governing pilot certification. If no further IFR (Instrument Flight Rules) flights are made after successfully completing the check, the pilot's currency would expire after 6 calendar months. It is important for pilots to regularly practice and maintain their instrument flying skills to ensure safe and proficient operations.