222
14 CFR Ch. I (1–1–14 Edition)
§ 23.443
(1) Steady slip conditions;
(2) Uncoordinated rolls from steep
banks; or
(3) Sudden failure of the critical en-
gine with delayed corrective action.
[Doc. No. 4080, 29 FR 17955, Dec. 18, 1964, as
amended by Amdt. 23–7, 34 FR 13090, Aug. 13,
1969; Amdt. 23–14, 38 FR 31821, Nov. 19, 1973;
Amdt. 23–28, 47 FR 13315, Mar. 29, 1982; Amdt.
23–42, 56 FR 353, Jan. 3, 1991; Amdt. 23–48, 61
FR 5145, Feb. 9, 1996]
§ 23.443
Gust loads.
(a) Vertical surfaces must be de-
signed to withstand, in unaccelerated
flight at speed
V
C,
lateral gusts of the
values prescribed for
V
C
in § 23.333(c).
(b) In addition, for commuter cat-
egory airplanes, the airplane is as-
sumed to encounter derived gusts nor-
mal to the plane of symmetry while in
unaccelerated flight at V
B
, V
C
, V
D
, and
V
F
. The derived gusts and airplane
speeds corresponding to these condi-
tions, as determined by §§ 23.341 and
23.345, must be investigated. The shape
of the gust must be as specified in
§ 23.333(c)(2)(i).
(c) In the absence of a more rational
analysis, the gust load must be com-
puted as follows:
L
K
U
V a
S
vt
gt
de
vt
vt
=
498
Where—
L
vt
=Vertical surface loads (lbs.);
k
gt
gt
gt
=
+
=
0 88
5 3
.
.
μ
μ
gust alleviation factor;
μ
ρ
gt
t
vt
vt
vt
W
c g a S
K
l
lateral
=
=
2
2
massratio;
U
de
=Derived gust velocity (f.p.s.);
r=Air density (slugs/cu.ft.);
W=the applicable weight of the airplane in
the particular load case (lbs.);
S
vt
=Area of vertical surface (ft.
2
);
c
¯
t
=Mean geometric chord of vertical surface
(ft.);
a
vt
=Lift curve slope of vertical surface (per
radian);
K=Radius of gyration in yaw (ft.);
l
vt
=Distance from airplane c.g. to lift center
of vertical surface (ft.);
g=Acceleration due to gravity (ft./sec.
2
); and
V=Equivalent airspeed (knots).
[Amdt. 23–7, 34 FR 13090, Aug. 13, 1969, as
amended by Amdt. 23–34, 52 FR 1830, Jan. 15,
1987; 52 FR 7262, Mar. 9, 1987; Amdt. 23–24, 52
FR 34745, Sept. 14, 1987; Amdt. 23–42, 56 FR
353, Jan. 3, 1991; Amdt. 23–48, 61 FR 5147, Feb.
9, 1996]
§ 23.445
Outboard fins or winglets.
(a) If outboard fins or winglets are in-
cluded on the horizontal surfaces or
wings, the horizontal surfaces or wings
must be designed for their maximum
load in combination with loads induced
by the fins or winglets and moments or
forces exerted on the horizontal sur-
faces or wings by the fins or winglets.
(b) If outboard fins or winglets ex-
tend above and below the horizontal
surface, the critical vertical surface
loading (the load per unit area as de-
termined under §§ 23.441 and 23.443)
must be applied to—
(1) The part of the vertical surfaces
above the horizontal surface with 80
percent of that loading applied to the
part below the horizontal surface; and
(2) The part of the vertical surfaces
below the horizontal surface with 80
percent of that loading applied to the
part above the horizontal surface.
(c) The end plate effects of outboard
fins or winglets must be taken into ac-
count in applying the yawing condi-
tions of §§ 23.441 and 23.443 to the
vertical surfaces in paragraph (b) of
this section.
(d) When rational methods are used
for computing loads, the maneuvering
loads of § 23.441 on the vertical surfaces
and the one-g horizontal surface load,
including induced loads on the hori-
zontal surface and moments or forces
exerted on the horizontal surfaces by
the vertical surfaces, must be applied
simultaneously for the structural load-
ing condition.
[Doc. No. 4080, 29 FR 17955, Dec. 18, 1964, as
amended by Amdt. 23–14, 38 FR 31821, Nov. 19,
1973; Amdt. 23–42, 56 FR 353, Jan. 3, 1991]
A
ILERONS AND
S
PECIAL
D
EVICES
§ 23.455
Ailerons.
(a) The ailerons must be designed for
the loads to which they are subjected—
(1) In the neutral position during
symmetrical flight conditions; and
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