605 

Federal Aviation Administration, DOT 

§ 29.672 

§ 29.561(b)(3) multiplied by a fitting fac-
tor of 1.33. 

[Doc. No. 5084, 29 FR 16150, Dec. 3, 1964, as 
amended by Amdt. 29–42, 63 FR 43285, Aug. 12, 
1998] 

§ 29.629

Flutter and divergence. 

Each aerodynamic surface of the 

rotorcraft must be free from flutter 
and divergence under each appropriate 
speed and power condition. 

[Doc. No. 28008, 61 FR 21907, May 10, 1996] 

§ 29.631

Bird strike. 

The rotorcraft must be designed to 

ensure capability of continued safe 
flight and landing (for Category A) or 
safe landing (for Category B) after im-
pact with a 2.2-lb (1.0 kg) bird when the 
velocity of the rotorcraft (relative to 
the bird along the flight path of the 
rotorcraft) is equal to V

NE

or V

H

 

(whichever is the lesser) at altitudes up 
to 8,000 feet. Compliance must be 
shown by tests or by analysis based on 
tests carried out on sufficiently rep-
resentative structures of similar de-
sign. 

[Doc. No. 28008, 61 FR 21907, May 10, 1996; 61 
FR 33963, July 1, 1996] 

R

OTORS

 

§ 29.653

Pressure venting and drain-

age of rotor blades. 

(a) For each rotor blade— 
(1) There must be means for venting 

the internal pressure of the blade; 

(2) Drainage holes must be provided 

for the blade; and 

(3) The blade must be designed to pre-

vent water from becoming trapped in 
it. 

(b) Paragraphs (a)(1) and (2) of this 

section does not apply to sealed rotor 
blades capable of withstanding the 
maximum pressure differentials ex-
pected in service. 

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

§ 29.659

Mass balance. 

(a) The rotor and blades must be 

mass balanced as necessary to— 

(1) Prevent excessive vibration; and 
(2) Prevent flutter at any speed up to 

the maximum forward speed. 

(b) The structural integrity of the 

mass balance installation must be sub-
stantiated. 

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

§ 29.661

Rotor blade clearance. 

There must be enough clearance be-

tween the rotor blades and other parts 
of the structure to prevent the blades 
from striking any part of the structure 
during any operating condition. 

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

§ 29.663

Ground resonance prevention 

means. 

(a) The reliability of the means for 

preventing ground resonance must be 
shown either by analysis and tests, or 
reliable service experience, or by show-
ing through analysis or tests that mal-
function or failure of a single means 
will not cause ground resonance. 

(b) The probable range of variations, 

during service, of the damping action 
of the ground resonance prevention 
means must be established and must be 
investigated during the test required 
by § 29.241. 

[Amdt. 27–26, 55 FR 8003, Mar. 6, 1990] 

C

ONTROL

S

YSTEMS

 

§ 29.671

General. 

(a) Each control and control system 

must operate with the ease, smooth-
ness, and positiveness appropriate to 
its function. 

(b) Each element of each flight con-

trol system must be designed, or dis-
tinctively and permanently marked, to 
minimize the probability of any incor-
rect assembly that could result in the 
malfunction of the system. 

(c) A means must be provided to 

allow full control movement of all pri-
mary flight controls prior to flight, or 
a means must be provided that will 
allow the pilot to determine that full 
control authority is available prior to 
flight. 

[Doc. No. 5084, 29 FR 16150, Dec. 3, 1964, as 
amended by Amdt. 29–24, 49 FR 44437, Nov. 6, 
1984] 

§ 29.672

Stability augmentation, auto-

matic, and power-operated systems. 

If the functioning of stability aug-

mentation or other automatic or 

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