394
14 CFR Ch. I (1–1–14 Edition)
§ 25.231
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
SR
; and
(3) The power or thrust necessary to
maintain level flight at 1.3 V
SR
.
(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) For flight in icing conditions be-
fore the ice protection system has been
activated and is performing its in-
tended function, with the ice accretion
defined in appendix C, part II(e) of this
part, the stall warning margin in
straight and turning flight must be suf-
ficient to allow the pilot to prevent
stalling without encountering any ad-
verse 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]
G
ROUND AND
W
ATER
H
ANDLING
C
HARACTERISTICS
§ 25.231
Longitudinal stability and
control.
(a) Landplanes may have no uncon-
trollable tendency to nose over in any
reasonably expected operating condi-
tion or when rebound occurs during
landing or takeoff. In addition—
(1) Wheel brakes must operate
smoothly and may not cause any undue
tendency to nose over; and
(2) If a tail-wheel landing gear is
used, it must be possible, during the
takeoff ground run on concrete, to
maintain any attitude up to thrust line
level, at 75 percent of
V
SR1
.
(b) For seaplanes and amphibians,
the most adverse water conditions safe
for takeoff, taxiing, and landing, must
be established.
[Docket No. 5066, 29 FR 18291, Dec. 24, 1964, as
amended by Amdt. 25–108, 67 FR 70828, Nov.
26, 2002]
§ 25.233
Directional stability and con-
trol.
(a) There may be no uncontrollable
ground-looping tendency in 90
°
cross
winds, up to a wind velocity of 20 knots
or 0.2
V
SR0
, whichever is greater, except
that the wind velocity need not exceed
25 knots at any speed at which the air-
plane may be expected to be operated
on the ground. This may be shown
while establishing the 90
°
cross compo-
nent of wind velocity required by
§ 25.237.
(b) Landplanes must be satisfactorily
controllable, without exceptional pilot-
ing skill or alertness, in power-off land-
ings at normal landing speed, without
using brakes or engine power to main-
tain a straight path. This may be
shown during power-off landings made
in conjunction with other tests.
(c) The airplane must have adequate
directional control during taxiing. This
may be shown during taxiing prior to
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