14 CFR § 25.201

Stalls must be shown in straight flight and in 30 degree banked turns with—

Power off; and

The power necessary to maintain level flight at 1.5 VSR1 (where VSR1 corresponds to the reference stall speed at maximum landing weight with flaps in the approach position and the landing gear retracted).

In each condition required by paragraph (a) of this section, it must be possible to meet the applicable requirements of § 25.203 with—

Flaps, landing gear, and deceleration devices in any likely combination of positions approved for operation;

Representative weights within the range for which certification is requested;

The most adverse center of gravity for recovery; and

The airplane trimmed for straight flight at the speed prescribed in § 25.103(b)(6).

The following procedures must be used to show compliance with § 25.203;

Starting at a speed sufficiently above the stalling speed to ensure that a steady rate of speed reduction can be established, apply the longitudinal control so that the speed reduction does not exceed one knot per second until the airplane is stalled.

In addition, for turning flight stalls, apply the longitudinal control to achieve airspeed deceleration rates up to 3 knots per second.

As soon as the airplane is stalled, recover by normal recovery techniques.

The airplane is considered stalled when the behavior of the airplane gives the pilot a clear and distinctive indication of an acceptable nature that the airplane is stalled. Acceptable indications of a stall, occurring either individually or in combination, are—

A nose-down pitch that cannot be readily arrested;

Buffeting, of a magnitude and severity that is a strong and effective deterrent to further speed reduction; or

The pitch control reaches the aft stop and no further increase in pitch attitude occurs when the control is held full aft for a short time before recovery is initiated.