220
14 CFR Ch. I (1–1–24 Edition)
§ 25.145
exceeding a pull control force of 50
pounds; and
(3) Any changes in force that the
pilot must apply to the pitch control to
maintain speed with increasing sideslip
angle must be steadily increasing with
no force reversals, unless the change in
control force is gradual and easily con-
trollable by the pilot without using ex-
ceptional piloting skill, alertness, or
strength.
(j) For flight in icing conditions be-
fore the ice protection system has been
activated and is performing its in-
tended function, it must be dem-
onstrated in flight with the most crit-
ical of the ice accretion(s) defined in
Appendix C, part II, paragraph (e) of
this part and Appendix O, part II, para-
graph (d) of this part, as applicable, in
accordance with § 25.21(g), that:
(1) The airplane is controllable in a
pull-up maneuver up to 1.5 g load fac-
tor; and
(2) There is no pitch control force re-
versal during a pushover maneuver
down to 0.5 g load factor.
[Doc. No. 5066, 29 FR 18291, Dec. 24, 1964, as
amended by Amdt. 25–42, 43 FR 2321, Jan. 16,
1978; Amdt. 25–84, 60 FR 30749, June 9, 1995;
Amdt. 25–108, 67 FR 70826, Nov. 26, 2002;
Amdt. 25–121, 72 FR 44667, Aug. 8, 2007; Amdt.
25–129, 74 FR 38339, Aug. 3, 2009; Amdt. 25–140,
79 FR 65525, Nov. 4, 2014]
§ 25.145
Longitudinal control.
(a) It must be possible, at any point
between the trim speed prescribed in
§ 25.103(b)(6) and stall identification (as
defined in § 25.201(d)), to pitch the nose
downward so that the acceleration to
this selected trim speed is prompt with
(1) The airplane trimmed at the trim
speed prescribed in § 25.103(b)(6);
(2) The landing gear extended;
(3) The wing flaps (i) retracted and
(ii) extended; and
(4) Power (i) off and (ii) at maximum
continuous power on the engines.
(b) With the landing gear extended,
no change in trim control, or exertion
of more than 50 pounds control force
(representative of the maximum short
term force that can be applied readily
by one hand) may be required for the
following maneuvers:
(1) With power off, flaps retracted,
and the airplane trimmed at 1.3 V
SR1
,
extend the flaps as rapidly as possible
while maintaining the airspeed at ap-
proximately 30 percent above the ref-
erence stall speed existing at each in-
stant throughout the maneuver.
(2) Repeat paragraph (b)(1) except ini-
tially extend the flaps and then retract
them as rapidly as possible.
(3) Repeat paragraph (b)(2), except at
the go-around power or thrust setting.
(4) With power off, flaps retracted,
and the airplane trimmed at 1.3 V
SR1
,
rapidly set go-around power or thrust
while maintaining the same airspeed.
(5) Repeat paragraph (b)(4) except
with flaps extended.
(6) With power off, flaps extended,
and the airplane trimmed at 1.3 V
SR1
,
obtain and maintain airspeeds between
V
SW
and either 1.6 V
SR1
or V
FE
, which-
ever is lower.
(c) It must be possible, without ex-
ceptional piloting skill, to prevent loss
of altitude when complete retraction of
the high lift devices from any position
is begun during steady, straight, level
flight at 1.08 V
SR1
for propeller powered
airplanes, or 1.13 V
SR1
for turbojet pow-
ered airplanes, with—
(1) Simultaneous movement of the
power or thrust controls to the go-
around power or thrust setting;
(2) The landing gear extended; and
(3) The critical combinations of land-
ing weights and altitudes.
(d) If gated high-lift device control
positions are provided, paragraph (c) of
this section applies to retractions of
the high-lift devices from any position
from the maximum landing position to
the first gated position, between gated
positions, and from the last gated posi-
tion to the fully retracted position.
The requirements of paragraph (c) of
this section also apply to retractions
from each approved landing position to
the control position(s) associated with
the high-lift device configuration(s)
used to establish the go-around proce-
dure(s) from that landing position. In
addition, the first gated control posi-
tion from the maximum landing posi-
tion must correspond with a configura-
tion of the high-lift devices used to es-
tablish a go-around procedure from a
landing configuration. Each gated con-
trol position must require a separate
and distinct motion of the control to
pass through the gated position and
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§ 25.149
must have features to prevent inad-
vertent movement of the control
through the gated position. It must
only be possible to make this separate
and distinct motion once the control
has reached the gated position.
[Doc. No. 5066, 29 FR 18291, Dec. 24, 1964, as
amended by Amdt. 25–23, 35 FR 5671, Apr. 8,
1970; Amdt. 25–72, 55 FR 29774, July 20, 1990;
Amdt. 25–84, 60 FR 30749, June 9, 1995; Amdt.
25–98, 64 FR 6164, Feb. 8, 1999; 64 FR 10740,
Mar. 5, 1999; Amdt. 25–108, 67 FR 70827, Nov.
26, 2002]
§ 25.147
Directional and lateral con-
trol.
(a)
Directional control; general. It must
be possible, with the wings level, to
yaw into the operative engine and to
safely make a reasonably sudden
change in heading of up to 15 degrees in
the direction of the critical inoperative
engine. This must be shown at 1.3 V
S
R1
for heading changes up to 15 degrees
(except that the heading change at
which the rudder pedal force is 150
pounds need not be exceeded), and
with—
(1) The critical engine inoperative
and its propeller in the minimum drag
position;
(2) The power required for level flight
at 1.3
V
S
R1, but not more than max-
imum continuous power;
(3) The most unfavorable center of
gravity;
(4) Landing gear retracted;
(5) Flaps in the approach position;
and
(6) Maximum landing weight.
(b)
Directional control; airplanes with
four or more engines. Airplanes with
four or more engines must meet the re-
quirements of paragraph (a) of this sec-
tion except that—
(1) The two critical engines must be
inoperative with their propellers (if ap-
plicable) in the minimum drag posi-
tion;
(2) [Reserved]
(3) The flaps must be in the most fa-
vorable climb position.
(c)
Lateral control; general. It must be
possible to make 20
°
banked turns, with
and against the inoperative engine,
from steady flight at a speed equal to
1.3
V
S
R1, with—
(1) The critical engine inoperative
and its propeller (if applicable) in the
minimum drag position;
(2) The remaining engines at max-
imum continuous power;
(3) The most unfavorable center of
gravity;
(4) Landing gear (i) retracted and (ii)
extended;
(5) Flaps in the most favorable climb
position; and
(6) Maximum takeoff weight.
(d)
Lateral control; roll capability. With
the critical engine inoperative, roll re-
sponse must allow normal maneuvers.
Lateral control must be sufficient, at
the speeds likely to be used with one
engine inoperative, to provide a roll
rate necessary for safety without ex-
cessive control forces or travel.
(e)
Lateral control; airplanes with four
or more engines. Airplanes with four or
more engines must be able to make 20
°
banked turns, with and against the in-
operative engines, from steady flight at
a speed equal to 1.3
V
S
R1, with max-
imum continuous power, and with the
airplane in the configuration pre-
scribed by paragraph (b) of this section.
(f)
Lateral control; all engines oper-
ating. With the engines operating, roll
response must allow normal maneuvers
(such as recovery from upsets produced
by gusts and the initiation of evasive
maneuvers). There must be enough ex-
cess lateral control in sideslips (up to
sideslip angles that might be required
in normal operation), to allow a lim-
ited amount of maneuvering and to
correct for gusts. Lateral control must
be enough at any speed up to
V
FC
/
M
FC
to provide a peak roll rate necessary
for safety, without excessive control
forces or travel.
[Doc. No. 5066, 29 FR 18291, Dec. 24, 1964, as
amended by Amdt. 25–42, 43 FR 2321, Jan. 16,
1978; Amdt. 25–72, 55 FR 29774, July 20, 1990;
Amdt. 25–108, 67 FR 70827, Nov. 26, 2002;
Amdt. 25–115, 69 FR 40527, July 2, 2004]
§ 25.149
Minimum control speed.
(a) In establishing the minimum con-
trol speeds required by this section, the
method used to simulate critical en-
gine failure must represent the most
critical mode of powerplant failure
with respect to controllability ex-
pected in service.
(b) V
MC
is the calibrated airspeed at
which, when the critical engine is sud-
denly made inoperative, it is possible
to maintain control of the airplane
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