title-14-part-25-sec25-207

227

Federal Aviation Administration, DOT

§ 25.207

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.

(b) For level wing stalls, the roll oc-

curring between the stall and the com-
pletion of the recovery may not exceed
approximately 20 degrees.

tion of the airplane after the stall may
not be so violent or extreme as to
make it difficult, with normal piloting
skill, to effect a prompt recovery and
to regain control of the airplane. The
maximum bank angle that occurs dur-
ing the recovery may not exceed—

(1) Approximately 60 degrees in the

original direction of the turn, or 30 de-
grees in the opposite direction, for de-
celeration rates up to 1 knot per sec-
ond; and

(2) Approximately 90 degrees in the

original direction of the turn, or 60 de-
grees in the opposite direction, for de-
celeration rates in excess of 1 knot per
second.

[Doc. No. 5066, 29 FR 18291, Dec. 24, 1964, as
amended by Amdt. 25–84, 60 FR 30750, June 9,
1995]

§ 25.207

Stall warning.

(a) Stall warning with sufficient mar-

gin to prevent inadvertent stalling
with the flaps and landing gear in any
normal position must be clear and dis-
tinctive to the pilot in straight and
turning flight.

(b) The warning must be furnished ei-

ther through the inherent aerodynamic
qualities of the airplane or by a device
that will give clearly distinguishable
indications under expected conditions
of flight. However, a visual stall warn-
ing device that requires the attention
of the crew within the cockpit is not
acceptable by itself. If a warning de-
vice is used, it must provide a warning
in each of the airplane configurations
prescribed in paragraph (a) of this sec-
tion at the speed prescribed in para-
graphs (c) and (d) of this section. Ex-
cept for the stall warning prescribed in
paragraph (h)(3)(ii) of this section, the
stall warning for flight in icing condi-
tions must be provided by the same
means as the stall warning for flight in
non-icing conditions.

not exceeding one knot per second,
stall warning must begin, in each nor-
mal configuration, at a speed, V

, ex-

ceeding the speed at which the stall is
identified in accordance with § 25.201(d)
by not less than five knots or five per-
cent CAS, whichever is greater. Once
initiated, stall warning must continue
until the angle of attack is reduced to
approximately that at which stall
warning began.

(d) In addition to the requirement of

paragraph (c) of this section, when the
speed is reduced at rates not exceeding
one knot per second, in straight flight
with engines idling and at the center-
of-gravity position specified in
§ 25.103(b)(5), V

, in each normal con-

figuration, must exceed V

by not less

than three knots or three percent CAS,
whichever is greater.

(e) In icing conditions, the stall

warning margin in straight and turn-
ing flight must be sufficient to allow
the pilot to prevent stalling (as defined
in § 25.201(d)) when the pilot starts a re-
covery maneuver not less than three
seconds after the onset of stall warn-
ing. When demonstrating compliance
with this paragraph, the pilot must
perform the recovery maneuver in the

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14 CFR Ch. I (1–1–24 Edition)

§ 25.231

same way as for the airplane in non-
icing conditions. Compliance with this
requirement must be demonstrated in
flight with the speed reduced at rates
not exceeding one knot per second,
with—

(1) The most critical of the takeoff

ice and final takeoff ice accretions de-
fined in Appendices C and O of this
part, as applicable, in accordance with
§ 25.21(g), for each configuration used in
the takeoff phase of flight;

(2) The most critical of the en route

ice accretion(s) defined in Appendices C
and O of this part, as applicable, in ac-
cordance with § 25.21(g), for the en
route configuration;

(3) The most critical of the holding

ice accretion(s) defined in Appendices C
and O of this part, as applicable, in ac-
cordance with § 25.21(g), for the holding
configuration(s);

(4) The most critical of the approach

ice accretion(s) defined in Appendices C
and O of this part, as applicable, in ac-
cordance with § 25.21(g), for the ap-
proach configuration(s); and

(5) The most critical of the landing

ice accretion(s) defined in Appendices C
and O of this part, as applicable, in ac-
cordance with § 25.21(g), for the landing
and go-around configuration(s).

(f) The stall warning margin must be

sufficient in both non-icing and icing
conditions to allow the pilot to prevent
stalling when the pilot starts a recov-
ery maneuver not less than one second
after the onset of stall warning in slow-
down turns with at least 1.5 g load fac-
tor normal to the flight path and air-
speed deceleration rates of at least 2
knots per second. When demonstrating
compliance with this paragraph for
icing conditions, the pilot must per-
form the recovery maneuver in the
same way as for the airplane in non-
icing conditions. Compliance with this
requirement must be demonstrated in
flight with—

(1) The flaps and landing gear in any

normal position;

(2) The airplane trimmed for straight

flight at a speed of 1.3 V

; and

(3) The power or thrust necessary to

maintain level flight at 1.3 V

(g) Stall warning must also be pro-

vided in each abnormal configuration
of the high lift devices that is likely to
be used in flight following system fail-

ures (including all configurations cov-
ered by Airplane Flight Manual proce-
dures).

(h) The following stall warning mar-

gin is required for flight in icing condi-
tions before the ice protection system
has been activated and is performing
its intended function. Compliance must
be shown using the most critical of the
ice accretion(s) defined in Appendix C,
part II, paragraph (e) of this part and
Appendix O, part II, paragraph (d) of
this part, as applicable, in accordance
with § 25.21(g). The stall warning mar-
gin in straight and turning flight must
be sufficient to allow the pilot to pre-
vent stalling without encountering any
adverse flight characteristics when:

(1) The speed is reduced at rates not

exceeding one knot per second;

(2) The pilot performs the recovery

maneuver in the same way as for flight
in non-icing conditions; and

(3) The recovery maneuver is started

no earlier than:

(i) One second after the onset of stall

warning if stall warning is provided by
the same means as for flight in non-
icing conditions; or

(ii) Three seconds after the onset of

stall warning if stall warning is pro-
vided by a different means than for
flight in non-icing conditions.

(i) In showing compliance with para-

graph (h) of this section, if stall warn-
ing is provided by a different means in
icing conditions than for non-icing con-
ditions, compliance with § 25.203 must
be shown using the accretion defined in
appendix C, part II(e) of this part. Com-
pliance with this requirement must be
shown using the demonstration pre-
scribed by § 25.201, except that the de-
celeration rates of § 25.201(c)(2) need not
be demonstrated.

[Doc. No. 5066, 29 FR 18291, Dec. 24, 1964, as
amended by Amdt. 25–7, 30 FR 13118, Oct. 15,
1965; Amdt. 25–42, 43 FR 2322, Jan. 16, 1978;
Amdt. 25–108, 67 FR 70827, Nov. 26, 2002;
Amdt. 25–121, 72 FR 44668, Aug. 8, 2007; Amdt.
25–129, 74 FR 38339, Aug. 3, 2009; Amdt. 25–140,
79 FR 65526, Nov. 4, 2014]

ROUND AND

ATER

ANDLING

HARACTERISTICS

§ 25.231

Longitudinal stability and

control.

(a) Landplanes may have no uncon-

trollable tendency to nose over in any