Code of Federal Regulations - Title 14

203

Federal Aviation Administration, DOT

§ 23.181

(c)

Landing. The stick force curve

must have a stable slope at speeds be-
tween 1.1 V

and 1.8 V

with—

(1) Flaps in the landing position;
(2) Landing gear extended; and
(3) The airplane trimmed at—
(i) V

REF

, or the minimum trim speed

if higher, with power off; and

(ii) V

REF

with enough power to main-

tain a 3 degree angle of descent.

[Doc. No. 27807, 61 FR 5190, Feb. 9, 1996]

§ 23.177

Static directional and lateral

stability.

(a)(1) The static directional stability,

as shown by the tendency to recover
from a wings level sideslip with the
rudder free, must be positive for any
landing gear and flap position appro-
priate to the takeoff, climb, cruise, ap-
proach, and landing configurations.
This must be shown with symmetrical
power up to maximum continuous
power, and at speeds from 1.2 V

up to

, V

FC,

whichever is ap-

propriate.

(2) The angle of sideslip for these

tests must be appropriate to the type
of airplane. The rudder pedal force
must not reverse at larger angles of
sideslip, up to that at which full rudder
is used or a control force limit in
§ 23.143 is reached, whichever occurs
first, and at speeds from 1.2 V

to V

(b)(1) The static lateral stability, as

shown by the tendency to raise the low
wing in a sideslip with the aileron con-
trols free, may not be negative for any
landing gear and flap position appro-
priate to the takeoff, climb, cruise, ap-
proach, and landing configurations.
This must be shown with symmetrical
power from idle up to 75 percent of
maximum continuous power at speeds
from 1.2 V

in the takeoff configura-

tion(s) and at speeds from 1.3 V

other configurations, up to the max-
imum allowable airspeed for the con-
figuration being investigated (V

, V

FC,

whichever is appropriate)

in the takeoff, climb, cruise, descent,
and approach configurations. For the
landing configuration, the power must
be that necessary to maintain a 3-de-
gree angle of descent in coordinated
flight.

(2) The static lateral stability may

not be negative at 1.2 V

in the takeoff

configuration, or at 1.3 V

in other

configurations.

(3) The angel of sideslip for these

tests must be appropriate to the type
of airplane, but in no case may the con-
stant heading sideslip angle be less
than that obtainable with a 10 degree
bank or, if less, the maximum bank
angle obtainable with full rudder de-
flection or 150 pound rudder force.

not apply to acrobatic category air-
planes certificated for inverted flight.

(d)(1) In straight, steady slips at 1.2

for any landing gear and flap posi-

tion appropriate to the takeoff, climb,
cruise, approach, and landing configu-
rations, and for any symmetrical power
conditions up to 50 percent of max-
imum continuous power, the aileron
and rudder control movements and
forces must increase steadily, but not
necessarily in constant proportion, as
the angle of sideslip is increased up to
the maximum appropriate to the type
of airplane.

(2) At larger slip angles, up to the

angle at which the full rudder or aile-
ron control is used or a control force
limit contained in § 23.143 is reached,
the aileron and rudder control move-
ments and forces may not reverse as
the angle of sideslip is increased.

(3) Rapid entry into, and recovery

from, a maximum sideslip considered
appropriate for the airplane may not
result in uncontrollable flight charac-
teristics.

[Doc. No. 27807, 61 FR 5190, Feb. 9, 1996, as
amended by Amdt. 23–62, 76 FR 75754, Dec. 2,
2011]

§ 23.181

Dynamic stability.

(a) Any short period oscillation not

including combined lateral-directional
oscillations occurring between the
stalling speed and the maximum allow-
able speed appropriate to the configu-
ration of the airplane must be heavily
damped with the primary controls—

(1) Free; and
(2) In a fixed position.
(b) Any combined lateral-directional

oscillations (Dutch roll) occurring be-
tween the stalling speed and the max-
imum allowable speed (V

, V

) appropriate to the configura-

tion of the airplane with the primary

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