14 CFR § 23.2110 - Stall speed.
§ 23.2110 Stall speed.
The applicant must determine the airplane stall speed or the minimum steady flight speed for each flight configuration used in normal operations, including takeoff, climb, cruise, descent, approach, and landing. The stall speed or minimum steady flight speed determination must account for the most adverse conditions for each flight configuration with power set at—
(a) Idle or zero thrust for propulsion systems that are used primarily for thrust; and
(b) A nominal thrust for propulsion systems that are used for thrust, flight control, and/or high-lift systems.