Code of Federal Regulations - Title 14

392

14 CFR Ch. I (1–1–14 Edition)

§ 25.181

steady sideslips, unless full lateral con-
trol input is achieved before reaching
either full rudder control input or a
rudder control force of 180 pounds; a
straight, steady sideslip need not be
maintained after achieving full lateral
control input. This requirement must
be met at all approved landing gear and
flap positions for the range of oper-
ating speeds and power conditions ap-
propriate to each landing gear and flap
position with all engines operating.

[Amdt. 25–135, 76 FR 74654, Dec. 1, 2011]

§ 25.181

Dynamic stability.

(a) Any short period oscillation, not

including combined lateral-directional
oscillations, occurring between 1.13 V

and maximum allowable speed appro-
priate to the configuration of the air-
plane must be heavily damped with the
primary controls—

(1) Free; and
(2) In a fixed position.
(b) Any combined lateral-directional

oscillations (‘‘Dutch roll’’) occurring
between 1.13 V

and maximum allow-

able speed appropriate to the configu-
ration of the airplane must be posi-
tively damped with controls free, and
must be controllable with normal use
of the primary controls without requir-
ing exceptional pilot skill.

[Amdt. 25–42, 43 FR 2322, Jan. 16, 1978, as
amended by Amdt. 25–72, 55 FR 29775, July 20,
1990; 55 FR 37607, Sept. 12, 1990; Amdt. 25–108,
67 FR 70827, Nov. 26, 2002]

TALLS

§ 25.201

Stall demonstration.

(a) Stalls must be shown in straight

flight and in 30 degree banked turns
with—

(1) Power off; and
(2) The power necessary to maintain

level flight at 1.5 V

SR1

(where V

SR1

cor-

responds to the reference stall speed at
maximum landing weight with flaps in
the approach position and the landing
gear retracted).

(b) In each condition required by

paragraph (a) of this section, it must
be possible to meet the applicable re-
quirements of § 25.203 with—

(1) Flaps, landing gear, and decelera-

tion devices in any likely combination
of positions approved for operation;

(2) Representative weights within the

range for which certification is re-
quested;

(3) The most adverse center of grav-

ity for recovery; and

(4) The airplane trimmed for straight

flight at the speed prescribed in
§ 25.103(b)(6).

used to show compliance with § 25.203;

(1) 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.

(2) In addition, for turning flight

stalls, apply the longitudinal control
to achieve airspeed deceleration rates
up to 3 knots per second.

(3) As soon as the airplane is stalled,

recover by normal recovery techniques.

(d) The airplane is considered stalled

when the behavior of the airplane gives
the pilot a clear and distinctive indica-
tion of an acceptable nature that the
airplane is stalled. Acceptable indica-
tions of a stall, occurring either indi-
vidually or in combination, are—

(1) A nose-down pitch that cannot be

readily arrested;

(2) Buffeting, of a magnitude and se-

verity that is a strong and effective de-
terrent to further speed reduction; or

(3) 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 re-
covery is initiated.

[Doc. No. 5066, 29 FR 18291, Dec. 24, 1964, as
amended by Amdt. 25–84, 60 FR 30750, June 9,
1995; Amdt. 25–108, 67 FR 70827, Nov. 26, 2002]

§ 25.203

Stall characteristics.

(a) It must be possible to produce and

to correct roll and yaw by unreversed
use of the aileron and rudder controls,
up to the time the airplane is stalled.
No abnormal nose-up pitching may
occur. The longitudinal control force
must be positive up to and throughout
the stall. In addition, it must be pos-
sible to promptly prevent stalling and
to recover from a stall by normal use
of the controls.

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