Federal Aviation Administration, DOT
Section 29.307

Section 29.339
FLIGHT LOADS

Proof of structure.

(a) Compliance with the strength and
deformation requirements of this subpart must be shown for each critical
loading condition accounting for the
environment to which the structure
will be exposed in operation. Structural analysis (static or fatigue) may
be used only if the structure conforms
to those structures for which experience has shown this method to be reliable. In other cases, substantiating
load tests must be made.
(b) Proof of compliance with the
strength requirements of this subpart
must include - 
(1) Dynamic and endurance tests of
rotors, rotor drives, and rotor controls;
(2) Limit load tests of the control
system, including control surfaces;
(3) Operation tests of the control system;
(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]

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Section 29.309

Design limitations.

The following values and limitations
must be established to show compliance 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 sideward flight speeds.
(e) The center of gravity limits corresponding to the limitations determined under paragraphs (b), (c), and (d)
of this section.
(f) The rotational speed ratios between each powerplant and each connected rotating component.
(g) The positive and negative limit
maneuvering load factors.

Section 29.321 General.
(a) The flight load factor must be assumed to act normal to the longitudinal axis of the rotorcraft, and to be
equal in magnitude and opposite in direction 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 maximum weight; and
(2) With any practical distribution of
disposable load within the operating
limitations in the Rotorcraft Flight
Manual.
Section 29.337 Limit maneuvering load factor.
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 Section1.0; or
(b) Any positive limit maneuvering
load factor not less than 2.0 and any
negative limit maneuvering load factor
of not less than Section0.5 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 appropriate to each weight condition between 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]

Section 29.339 Resultant limit maneuvering
loads.
The loads resulting from the application 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 surfaces, 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 component in the plane of the rotor disc to
the rotational tip speed of the rotor
blades, and is expressed as follows:

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