title-14-part-29-sec29-511

594

14 CFR Ch. I (1–1–24 Edition)

§ 29.505

(c)

Drag reactions in the level landing

attitude. In the level attitude, and with
the rotorcraft contacting the ground
along the bottom of both skids, the fol-
lowing apply:

(1) The vertical reactions must be

combined with horizontal drag reac-
tions of 50 percent of the vertical reac-
tion applied at the ground.

(2) The resultant ground loads must

equal the vertical load specified in
paragraph (b) of this section.

(d)

Sideloads in the level landing atti-

tude. In the level attitude, and with the
rotorcraft contacting the ground along
the bottom of both skids, the following
apply:

(1) The vertical ground reaction must

be—

(i) Equal to the vertical loads ob-

tained in the condition specified in
paragraph (b) of this section; and

(ii) Divided equally among the skids.
(2) The vertical ground reactions

must be combined with a horizontal
sideload of 25 percent of their value.

(3) The total sideload must be applied

equally between skids and along the
length of the skids.

(4) The unbalanced moments are as-

sumed to be resisted by angular iner-
tia.

(5) The skid gear must be inves-

tigated for—

(i) Inward acting sideloads; and
(ii) Outward acting sideloads.
(e)

One-skid landing loads in the level

attitude. In the level attitude, and with
the rotorcraft contacting the ground
along the bottom of one skid only, the
following apply:

(1) The vertical load on the ground

contact side must be the same as that
obtained on that side in the condition
specified in paragraph (b) of this sec-
tion.

(2) The unbalanced moments are as-

sumed to be resisted by angular iner-
tia.

(f)

Special conditions. In addition to

the conditions specified in paragraphs
(b) and (c) of this section, the rotor-
craft must be designed for the fol-
lowing ground reactions:

(1) A ground reaction load acting up

and aft at an angle of 45 degrees to the
longitudinal axis of the rotorcraft.
This load must be—

(i) Equal to 1.33 times the maximum

weight;

(ii) Distributed symmetrically among

the skids;

(iii) Concentrated at the forward end

of the straight part of the skid tube;
and

(iv) Applied only to the forward end

of the skid tube and its attachment to
the rotorcraft.

(2) With the rotorcraft in the level

landing attitude, a vertical ground re-
action load equal to one-half of the
vertical load determined under para-
graph (b) of this section. This load
must be—

(i) Applied only to the skid tube and

its attachment to the rotorcraft; and

(ii) Distributed equally over 33.3 per-

cent of the length between the skid
tube attachments and centrally located
midway between the skid tube attach-
ments.

[Amdt. 29–3, 33 FR 966, Jan. 26, 1968, as
amended by Amdt. 27–26, 55 FR 8002, Mar. 6,
1990]

§ 29.505

Ski landing conditions.

If certification for ski operation is

requested, the rotorcraft, with skis,
must be designed to withstand the fol-
lowing loading conditions (where

P is

the maximum static weight on each ski
with the rotorcraft at design maximum
weight, and

n is the limit load factor

determined under § 29.473(b)):

(a) Up-load conditions in which—
(1) A vertical load of

Pn and a hori-

zontal load of

Pn/4 are simultaneously

applied at the pedestal bearings; and

(2) A vertical load of 1.33

P is applied

at the pedestal bearings.

(b) A side load condition in which a

side load of 0.35

Pn is applied at the

pedestal bearings in a horizontal plane
perpendicular to the centerline of the
rotorcraft.

a torque load of 1.33

P (in foot-pounds)

is applied to the ski about the vertical
axis through the centerline of the ped-
estal bearings.

§ 29.511

Ground load: unsymmetrical

loads on multiple-wheel units.

(a) In dual-wheel gear units, 60 per-

cent of the total ground reaction for
the gear unit must be applied to one
wheel and 40 percent to the other.

VerDate Sep<11>2014

09:06 Jun 28, 2024

Jkt 262046

PO 00000

Frm 00604

Fmt 8010

Sfmt 8010

Y:\SGML\262046.XXX

262046

jspears on DSK121TN23PROD with CFR

595

Federal Aviation Administration, DOT

§ 29.547

(b) To provide for the case of one de-

flated tire, 60 percent of the specified
load for the gear unit must be applied
to either wheel except that the vertical
ground reaction may not be less than
the full static value.

gear unit, the transverse shift in the
load centroid, due to unsymmetrical
load distribution on the wheels, may be
neglected.

[Amdt. 29–3, 33 FR 966, Jan. 26, 1968]

ATER

OADS

§ 29.519

Hull type rotorcraft: Water-

based and amphibian.

(a)

General. For hull type rotorcraft,

the structure must be designed to with-
stand the water loading set forth in
paragraphs (b), (c), and (d) of this sec-
tion considering the most severe wave
heights and profiles for which approval
is desired. The loads for the landing
conditions of paragraphs (b) and (c) of
this section must be developed and dis-
tributed along and among the hull and
auxiliary floats, if used, in a rational
and conservative manner, assuming a
rotor lift not exceeding two-thirds of
the rotorcraft weight to act through-
out the landing impact.

(b)

Vertical landing conditions. The

rotorcraft must initially contact the
most critical wave surface at zero for-
ward speed in likely pitch and roll atti-
tudes which result in critical design
loadings. The vertical descent velocity
may not be less than 6.5 feet per second
relative to the mean water surface.

(c)

Forward speed landing conditions.

The rotorcraft must contact the most
critical wave at forward velocities
from zero up to 30 knots in likely
pitch, roll, and yaw attitudes and with
a vertical descent velocity of not less
than 6.5 feet per second relative to the
mean water surface. A maximum for-
ward velocity of less than 30 knots may
be used in design if it can be dem-
onstrated that the forward velocity se-
lected would not be exceeded in a nor-
mal one-engine-out landing.

(d)

Auxiliary float immersion condition.

In addition to the loads from the land-
ing conditions, the auxiliary float, and
its support and attaching structure in
the hull, must be designed for the load
developed by a fully immersed float un-

less it can be shown that full immer-
sion of the float is unlikely, in which
case the highest likely float buoyancy
load must be applied that considers
loading of the float immersed to create
restoring moments compensating for
upsetting moments caused by side
wind, asymmetrical rotorcraft loading,
water wave action, and rotorcraft iner-
tia.

[Amdt. 29–3, 33 FR 966, Jan. 26, 196, as amend-
ed by Amdt. 27–26, 55 FR 8002, Mar. 6, 1990]

§ 29.521

Float landing conditions.

If certification for float operation

(including float amphibian operation)
is requested, the rotorcraft, with
floats, must be designed to withstand
the following loading conditions (where
the limit load factor is determined
under § 29.473(b) or assumed to be equal
to that determined for wheel landing
gear):

(a) Up-load conditions in which—
(1) A load is applied so that, with the

rotorcraft in the static level attitude,
the resultant water reaction passes
vertically through the center of grav-
ity; and

(2) The vertical load prescribed in

paragraph (a)(1) of this section is ap-
plied simultaneously with an aft com-
ponent of 0.25 times the vertical com-
ponent

(b) A side load condition in which—
(1) A vertical load of 0.75 times the

total vertical load specified in para-
graph (a)(1) of this section is divided
equally among the floats; and

(2) For each float, the load share de-

termined under paragraph (b)(1) of this
section, combined with a total side
load of 0.25 times the total vertical
load specified in paragraph (b)(1) of
this section, is applied to that float
only.

[Amdt. 29–3, 33 FR 967, Jan. 26, 1968]

AIN

OMPONENT

EQUIREMENTS

§ 29.547

Main and tail rotor structure.

(a) A rotor is an assembly of rotating

components, which includes the rotor
hub, blades, blade dampers, the pitch
control mechanisms, and all other
parts that rotate with the assembly.

(b) Each rotor assembly must be de-

signed as prescribed in this section and