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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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221 

Federal Aviation Administration, DOT 

§ 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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