213
Federal Aviation Administration, DOT
§ 23.343
§ 23.337
Limit maneuvering load fac-
tors.
(a) The positive limit maneuvering
load factor
n may not be less than—
(1) 2.1+(24,000
÷
(W+10,000)) for normal
and commuter category airplanes,
where W=design maximum takeoff
weight, except that n need not be more
than 3.8;
(2) 4.4 for utility category airplanes;
or
(3) 6.0 for acrobatic category air-
planes.
(b) The negative limit maneuvering
load factor may not be less than—
(1) 0.4 times the positive load factor
for the normal utility and commuter
categories; or
(2) 0.5 times the positive load factor
for the acrobatic category.
(c) Maneuvering load factors lower
than those specified in this section
may be used if the airplane has design
features that make it impossible to ex-
ceed these values in flight.
[Doc. No. 4080, 29 FR 17955, Dec. 18, 1964, as
amended by Amdt. 23–7, 34 FR 13088, Aug. 13,
1969; Amdt. 23–34, 52 FR 1829, Jan. 15, 1987;
Amdt. 23–48, 61 FR 5144, Feb. 9, 1996]
§ 23.341
Gust loads factors.
(a) Each airplane must be designed to
withstand loads on each lifting surface
resulting from gusts specified in
§ 23.333(c).
(b) The gust load for a canard or tan-
dem wing configuration must be com-
puted using a rational analysis, or may
be computed in accordance with para-
graph (c) of this section, provided that
the resulting net loads are shown to be
conservative with respect to the gust
criteria of § 23.333(c).
(c) In the absence of a more rational
analysis, the gust load factors must be
computed as follows—
n
K U V a
W S
g
de
= +
1
498 (
/ )
Where—
K
g
=0.88
μ
g
/5.3+
μ
g
=gust alleviation factor;
μ
g
=2(W/S)/
r Cag=airplane mass ratio;
U
de
=Derived gust velocities referred to in
§ 23.333(c) (f.p.s.);
r=Density of air (slugs/cu.ft.);
W/S=Wing loading (p.s.f.) due to the applica-
ble weight of the airplane in the par-
ticular load case.
W/S=Wing loading (p.s.f.);
C=Mean geometric chord (ft.);
g=Acceleration due to gravity (ft./sec.
2
)
V=Airplane equivalent speed (knots); and
a=Slope of the airplane normal force coeffi-
cient curve
C
NA
per radian if the gust
loads are applied to the wings and hori-
zontal tail surfaces simultaneously by a
rational method. The wing lift curve
slope
C
L
per radian may be used when the
gust load is applied to the wings only and
the horizontal tail gust loads are treated
as a separate condition.
[Amdt. 23–7, 34 FR 13088, Aug. 13, 1969, as
amended by Amdt. 23–42, 56 FR 352, Jan. 3,
1991; Amdt. 23–48, 61 FR 5144, Feb. 9, 1996]
§ 23.343
Design fuel loads.
(a) The disposable load combinations
must include each fuel load in the
range from zero fuel to the selected
maximum fuel load.
(b) If fuel is carried in the wings, the
maximum allowable weight of the air-
plane without any fuel in the wing
tank(s) must be established as ‘‘max-
imum zero wing fuel weight,’’ if it is
less than the maximum weight.
(c) For commuter category airplanes,
a structural reserve fuel condition, not
exceeding fuel necessary for 45 minutes
of operation at maximum continuous
power, may be selected. If a structural
reserve fuel condition is selected, it
must be used as the minimum fuel
weight condition for showing compli-
ance with the flight load requirements
prescribed in this part and—
(1) The structure must be designed to
withstand a condition of zero fuel in
the wing at limit loads corresponding
to:
(i) Ninety percent of the maneu-
vering load factors defined in § 23.337,
and
(ii) Gust velocities equal to 85 per-
cent of the values prescribed in
§ 23.333(c).
(2) The fatigue evaluation of the
structure must account for any in-
crease in operating stresses resulting
from the design condition of paragraph
(c)(1) of this section.
(3) The flutter, deformation, and vi-
bration requirements must also be met
with zero fuel in the wings.
[Doc. No. 27805, 61 FR 5144, Feb. 9, 1996]
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