The document that specifies the requirements of a Flight Review is AC 61-98B. From 61-98B:

Under § 61.56(c) no person may act as PIC of an aircraft unless within the preceding 24 calendar-months that person has accomplished a satisfactory flight review in an aircraft for which that pilot is appropriately rated. An appropriately-rated instructor or other designated person must conduct the flight review. The purpose of the flight review is to provide for a regular evaluation of pilot skills and aeronautical
knowledge.

Pilots and CFIs should be aware that, under § 61.56(d), there is no requirement for pilots who have completed certain proficiency checks and ratings within the preceding 24 calendar-months to accomplish a separate flight review. These accomplishments include satisfactory completion of pilot proficiency checks conducted by the FAA, an approved pilot check airman, a Designated Pilot Examiner (DPE), or a U.S. Armed Force for a pilot certificate, rating, or operating privilege. However, the FAA recommends that pilots consider also accomplishing a review under some of the following circumstances. For example, a pilot with an Airplane Single-Engine Land (ASEL) rating may have recently obtained a glider rating, but may still wish to consider obtaining a flight review in a single-engine airplane if the appropriate 24-month period has nearly expired.

Review of Maneuvers and Procedures:
(1) The maneuvers and procedures covered during the review are those which, in the opinion of the CFI conducting the review, are necessary for the pilot to perform in order to demonstrate that he or she can safely exercise the privileges of his or her pilot certificate.
Accordingly, the CFI should evaluate the pilot’s skills and knowledge to the extent necessary to ensure that he or she can safely operate within regulatory requirements throughout a wide range of conditions. The CFI should always include abnormal and emergency procedures applicable to
the aircraft flown in the flight review.
(2) The CFI may wish to prepare a preliminary plan for the flight review based on an interview or other assessment of the pilot’s qualifications and skills. The CFI should outline a sequence of maneuvers to the pilot taking the review. For example, this may include a cross-country flight to another airport with maneuvers accomplished while en route. It could also include a period of simulated instrument flight time. The CFI should request that the pilot conduct whatever preflight preparation is necessary to complete the planned flight. This preparation should include all items required in part 91, § 91.103, such as checking weather, calculating required runway lengths, calculating Weight and Balance (W&B), completing a flight log, filing a flight plan, and conducting the preflight inspection.
(3) Before beginning the flight portion of the review, the CFI should discuss various operational areas with the pilot. This oral review should include, but not be limited to, areas such as aircraft systems, speeds, performance, meteorological and other hazards (e.g., windshear and wake turbulence), operations in controlled airspace, and abnormal and emergency procedures.
The emphasis during this discussion should be on practical knowledge of recommended procedures and regulatory requirements.
(4) Regardless of the pilot’s experience, the CFI may wish to review at least those maneuvers considered critical to safe flight, such as stalls, slow flight, and takeoffs and landings. Based on his or her in-flight assessment of the pilot’s skills, the CFI may wish to add other maneuvers from the PTS appropriate to the pilot’s grade of certificate. All reviews should include those areas within the PTS identified as “Special Emphasis.” Appendix 5 includes a list of suggested maneuvers. The FAA does not intend this list to be all-inclusive, nor does it limit a CFI’s discretion in selecting other appropriate maneuvers and procedures. To the greatest possible extent, the CFI should organize and sequence the selected maneuvers in a realistic
scenario appropriate to the kind of flying normally done by the pilot.
(5) The role of the CFI during the review is to provide an evaluation. However, the instructor is not limited to this role and may provide specific instruction to an airman on any areas the instructor notes as being weak. This additional instruction does not preclude the pilot’s successful completion of the review as long as the deficiencies are corrected. If the additional instruction does not correct the deficiencies, and/or it becomes apparent to the instructor that additional flights will be necessary, the CFI should discuss the situation with the pilot and proceed accordingly.

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