405
Federal Aviation Administration, DOT
§ 25.361
(a)
Maneuvering. The following condi-
tions, speeds, and aileron deflections
(except as the deflections may be lim-
ited by pilot effort) must be considered
in combination with an airplane load
factor of zero and of two-thirds of the
positive maneuvering factor used in de-
sign. In determining the required aile-
ron deflections, the torsional flexi-
bility of the wing must be considered
in accordance with § 25.301(b):
(1) Conditions corresponding to
steady rolling velocities must be inves-
tigated. In addition, conditions cor-
responding to maximum angular accel-
eration must be investigated for air-
planes with engines or other weight
concentrations outboard of the fuse-
lage. For the angular acceleration con-
ditions, zero rolling velocity may be
assumed in the absence of a rational
time history investigation of the ma-
neuver.
(2) At
V
A,
a sudden deflection of the
aileron to the stop is assumed.
(3) At
V
C,
the aileron deflection must
be that required to produce a rate of
roll not less than that obtained in
paragraph (a)(2) of this section.
(4) At
V
D,
the aileron deflection must
be that required to produce a rate of
roll not less than one-third of that in
paragraph (a)(2) of this section.
(b)
Unsymmetrical gusts. The airplane
is assumed to be subjected to unsym-
metrical vertical gusts in level flight.
The resulting limit loads must be de-
termined from either the wing max-
imum airload derived directly from
§ 25.341(a), or the wing maximum air-
load derived indirectly from the
vertical load factor calculated from
§ 25.341(a). It must be assumed that 100
percent of the wing air load acts on one
side of the airplane and 80 percent of
the wing air load acts on the other
side.
[Doc. No. 5066, 29 FR 18291, Dec. 24, 1964, as
amended by Amdt. 25–23, 35 FR 5672, Apr. 8,
1970; Amdt. 25–86, 61 FR 5222, Feb. 9, 1996;
Amdt. 25–94, 63 FR 8848, Feb. 23, 1998]
§ 25.351
Yaw maneuver conditions.
The airplane must be designed for
loads resulting from the yaw maneuver
conditions specified in paragraphs (a)
through (d) of this section at speeds
from V
MC
to V
D
. Unbalanced aero-
dynamic moments about the center of
gravity must be reacted in a rational
or conservative manner considering the
airplane inertia forces. In computing
the tail loads the yawing velocity may
be assumed to be zero.
(a) With the airplane in unacceler-
ated flight at zero yaw, it is assumed
that the cockpit rudder control is sud-
denly displaced to achieve the result-
ing rudder deflection, as limited by:
(1) The control system on control
surface stops; or
(2) A limit pilot force of 300 pounds
from V
MC
to V
A
and 200 pounds from V
C
/
M
C
to V
D
/M
D
, with a linear variation
between V
A
and V
C
/M
C
.
(b) With the cockpit rudder control
deflected so as always to maintain the
maximum rudder deflection available
within the limitations specified in
paragraph (a) of this section, it is as-
sumed that the airplane yaws to the
overswing sideslip angle.
(c) With the airplane yawed to the
static equilibrium sideslip angle, it is
assumed that the cockpit rudder con-
trol is held so as to achieve the max-
imum rudder deflection available with-
in the limitations specified in para-
graph (a) of this section.
(d) With the airplane yawed to the
static equilibrium sideslip angle of
paragraph (c) of this section, it is as-
sumed that the cockpit rudder control
is suddenly returned to neutral.
[Amdt. 25–91, 62 FR 40704, July 29, 1997]
S
UPPLEMENTARY
C
ONDITIONS
§ 25.361
Engine torque.
(a) Each engine mount and its sup-
porting structure must be designed for
the effects of—
(1) A limit engine torque cor-
responding to takeoff power and pro-
peller speed acting simultaneously
with 75 percent of the limit loads from
flight condition A of § 25.333(b);
(2) A limit torque corresponding to
the maximum continuous power and
propeller speed, acting simultaneously
with the limit loads from flight condi-
tion A of § 25.333(b); and
(3) For turbopropeller installations,
in addition to the conditions specified
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