588 

14 CFR Ch. I (1–1–24 Edition) 

§ 29.309 

(3) Operation tests of the control sys-

tem; 

(4) Flight stress measurement tests; 
(5) Landing gear drop tests; and 
(6) Any additional tests required for 

new or unusual design features. 

(Secs. 604, 605, 72 Stat. 778, 49 U.S.C. 1424, 
1425) 

[Doc. No. 5084, 29 FR 16150, Dec. 3, 1964, as 
amended by Amdt. 29–4, 33 FR 14106, Sept. 18, 
1968; Amdt. 27–26, 55 FR 8001, Mar. 6, 1990] 

§ 29.309

Design limitations. 

The following values and limitations 

must be established to show compli-
ance with the structural requirements 
of this subpart: 

(a) The design maximum and design 

minimum weights. 

(b) The main rotor r.p.m. ranges, 

power on and power off. 

(c) The maximum forward speeds for 

each main rotor r.p.m. within the 
ranges determined under paragraph (b) 
of this section. 

(d) The maximum rearward and side-

ward flight speeds. 

(e) The center of gravity limits cor-

responding to the limitations deter-
mined under paragraphs (b), (c), and (d) 
of this section. 

(f) The rotational speed ratios be-

tween each powerplant and each con-
nected rotating component. 

(g) The positive and negative limit 

maneuvering load factors. 

F

LIGHT

L

OADS

 

§ 29.321

General. 

(a) The flight load factor must be as-

sumed to act normal to the longitu-
dinal axis of the rotorcraft, and to be 
equal in magnitude and opposite in di-
rection to the rotorcraft inertia load 
factor at the center of gravity. 

(b) Compliance with the flight load 

requirements of this subpart must be 
shown— 

(1) At each weight from the design 

minimum weight to the design max-
imum weight; and 

(2) With any practical distribution of 

disposable load within the operating 
limitations in the Rotorcraft Flight 
Manual. 

§ 29.337

Limit maneuvering load fac-

tor. 

The rotorcraft must be designed for— 
(a) A limit maneuvering load factor 

ranging from a positive limit of 3.5 to 
a negative limit of 

¥

1.0; or 

(b) Any positive limit maneuvering 

load factor not less than 2.0 and any 
negative limit maneuvering load factor 
of not less than 

¥

0.5 for which— 

(1) The probability of being exceeded 

is shown by analysis and flight tests to 
be extremely remote; and 

(2) The selected values are appro-

priate to each weight condition be-
tween the design maximum and design 
minimum weights. 

[Doc. No. 5084, 29 FR 16150, Dec. 3, 1964, as 
amended by Amdt. 27–26, 55 FR 8002, Mar. 6, 
1990] 

§ 29.339

Resultant limit maneuvering 

loads. 

The loads resulting from the applica-

tion of limit maneuvering load factors 
are assumed to act at the center of 
each rotor hub and at each auxiliary 
lifting surface, and to act in directions 
and with distributions of load among 
the rotors and auxiliary lifting sur-
faces, so as to represent each critical 
maneuvering condition, including 
power-on and power-off flight with the 
maximum design rotor tip speed ratio. 
The rotor tip speed ratio is the ratio of 
the rotorcraft flight velocity compo-
nent in the plane of the rotor disc to 
the rotational tip speed of the rotor 
blades, and is expressed as follows: 

μ =

V cos a

R

Ω

where— 

V  = The airspeed along the flight path 

(f.p.s.); 

a = The angle between the projection, in the 

plane of symmetry, of the axis of no 
feathering and a line perpendicular to 
the flight path (radians, positive when 
axis is pointing aft); 

W 

= The angular velocity of rotor (radians 

per second); and 

R = The rotor radius (ft.). 

§ 29.341

Gust loads. 

Each rotorcraft must be designed to 

withstand, at each critical airspeed in-
cluding hovering, the loads resulting 

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