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. 

(c) In determining the total load on a 

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] 

W

ATER

L

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] 

M

AIN

C

OMPONENT

R

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 

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