Question: I hold an FAA pilot certificate and will be doing some flying in Germany. Before my checkout flight at the FBO in Germany I realized that I am coming due for a flight review. Can I complete the flight review with a German flight instructor?
Answer: No. Although 14 CFR Part 61.41 provides authorization for foreign flight instructors to provide flight training, there are limitations on that privilege. An “authorized instructor,” meaning a U.S.-certified flight instructor, is required for completion of a flight review. Unless the European flight instructor also holds an FAA flight instructor certificate, he or she would not be able to provide an endorsement for satisfactory completion of a flight review.
Source: FARs Explained by Kent S. Jackson, Part 61, page 55