224 

14 CFR Ch. I (1–1–19 Edition) 

§ 25.161 

(4) The most unfavorable weight, or, 

at the option of the applicant, as a 
function of weight; 

(5) For propeller airplanes, the pro-

peller of the more critical inoperative 
engine in the position it achieves with-
out pilot action, assuming the engine 
fails while at the power or thrust nec-
essary to maintain a three degree ap-
proach path angle, and the propeller of 
the other inoperative engine feathered; 

(6) The power or thrust on the oper-

ating engine(s) necessary to maintain 
an approach path angle of three de-
grees when one critical engine is inop-
erative; and 

(7) The power or thrust on the oper-

ating engine(s) rapidly changed, imme-
diately after the second critical engine 
is made inoperative, from the power or 
thrust prescribed in paragraph (g)(6) of 
this section to— 

(i) Minimum power or thrust; and 
(ii) Go-around power or thrust set-

ting. 

(h) In demonstrations of V

MCL

and 

V

MCL-2

— 

(1) The rudder force may not exceed 

150 pounds; 

(2) The airplane may not exhibit haz-

ardous flight characteristics or require 
exceptional piloting skill, alertness, or 
strength; 

(3) Lateral control must be sufficient 

to roll the airplane, from an initial 
condition of steady flight, through an 
angle of 20 degrees in the direction nec-
essary to initiate a turn away from the 
inoperative engine(s), in not more than 
5 seconds; and 

(4) For propeller airplanes, hazardous 

flight characteristics must not be ex-
hibited due to any propeller position 
achieved when the engine fails or dur-
ing any likely subsequent movements 
of the engine or propeller controls. 

[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; 55 
FR 37607, Sept. 12, 1990; Amdt. 25–84, 60 FR 
30749, June 9, 1995; Amdt. 25–108, 67 FR 70827, 
Nov. 26, 2002] 

T

RIM

 

§ 25.161

Trim. 

(a) 

General. 

Each airplane must meet 

the trim requirements of this section 
after being trimmed, and without fur-
ther pressure upon, or movement of, ei-

ther the primary controls or their cor-
responding trim controls by the pilot 
or the automatic pilot. 

(b) 

Lateral and directional trim. 

The 

airplane must maintain lateral and di-
rectional trim with the most adverse 
lateral displacement of the center of 
gravity within the relevant operating 
limitations, during normally expected 
conditions of operation (including op-
eration at any speed from 1.3 

V

SR

1

to 

V

MO

/M

MO

). 

(c) 

Longitudinal trim. 

The airplane 

must maintain longitudinal trim dur-
ing— 

(1) A climb with maximum contin-

uous power at a speed not more than 
1.3 

V

SR

1

, with the landing gear re-

tracted, and the flaps (i) retracted and 
(ii) in the takeoff position; 

(2) Either a glide with power off at a 

speed not more than 1.3 V

SR1

, or an ap-

proach within the normal range of ap-
proach speeds appropriate to the 
weight and configuration with power 
settings corresponding to a 3 degree 
glidepath, whichever is the most se-
vere, with the landing gear extended, 
the wing flaps (i) retracted and (ii) ex-
tended, and with the most unfavorable 
combination of center of gravity posi-
tion and weight approved for landing; 
and 

(3) Level flight at any speed from 1.3 

V

SR

1

, to 

V

MO

/M

MO,

with the landing gear 

and flaps retracted, and from 1.3 

V

SR

1

to 

V

LE

with the landing gear extended. 

(d) 

Longitudinal, directional, and lat-

eral trim. 

The airplane must maintain 

longitudinal, directional, and lateral 
trim (and for the lateral trim, the 
angle of bank may not exceed five de-
grees) at 1.3 

V

SR

1

during climbing flight 

with— 

(1) The critical engine inoperative; 
(2) The remaining engines at max-

imum continuous power; and 

(3) The landing gear and flaps re-

tracted. 

(e) Airplanes with four or more en-

gines. Each airplane with four or more 
engines must also maintain trim in 
rectilinear flight with the most unfa-
vorable center of gravity and at the 
climb speed, configuration, and power 
required by § 25.123(a) for the purpose of 

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