title-14-part-35-sec35-38

762

14 CFR Ch. I (1–1–24 Edition)

§ 35.35

prior to implementation and may re-
quire additional testing. Any unsched-
uled repair or action on the test article
must be recorded and reported.

[Amdt. 35–8, 73 FR 63348, Oct. 24, 2008]

§ 35.35

Centrifugal load tests.

The applicant must demonstrate that

a propeller complies with paragraphs
(a), (b) and (c) of this section without
evidence of failure, malfunction, or
permanent deformation that would re-
sult in a major or hazardous propeller
effect. When the propeller could be sen-
sitive to environmental degradation in
service, this must be considered. This
section does not apply to fixed-pitch
wood or fixed-pitch metal propellers of
conventional design.

(a) The hub, blade retention system,

and counterweights must be tested for
a period of one hour to a load equiva-
lent to twice the maximum centrifugal
load to which the propeller would be
subjected during operation at the max-
imum rated rotational speed.

(b) Blade features associated with

transitions to the retention system (for
example, a composite blade bonded to a
metallic retention) must be tested ei-
ther during the test of paragraph (a) of
this section or in a separate component
test for a period of one hour to a load
equivalent to twice the maximum cen-
trifugal load to which the propeller
would be subjected during operation at
the maximum rated rotational speed.

to the propeller (for example, spinners,
de-icing equipment, and blade erosion
shields) must be subjected to a load
equivalent to 159 percent of the max-
imum centrifugal load to which the
component would be subjected during
operation at the maximum rated rota-
tional speed. This must be performed
by either:

(1) Testing at the required load for a

period of 30 minutes; or

(2) Analysis based on test.

[Amdt. 35–8, 73 FR 63348, Oct. 24, 2008]

§ 35.36

Bird impact.

The applicant must demonstrate, by

tests or analysis based on tests or expe-
rience on similar designs, that the pro-
peller can withstand the impact of a 4-
pound bird at the critical location(s)

and critical flight condition(s) of a typ-
ical installation without causing a
major or hazardous propeller effect.
This section does not apply to fixed-
pitch wood propellers of conventional
design.

[Amdt. 35–8, 73 FR 63348, Oct. 24, 2008]

§ 35.37

Fatigue limits and evaluation.

This section does not apply to fixed-

pitch wood propellers of conventional
design.

(a) Fatigue limits must be estab-

lished by tests, or analysis based on
tests, for propeller:

(1) Hubs.
(2) Blades.
(3) Blade retention components.
(4) Components which are affected by

fatigue loads and which are shown
under § 35.15 to have a fatigue failure
mode leading to hazardous propeller ef-
fects.

(b) The fatigue limits must take into

account:

(1) All known and reasonably foresee-

able vibration and cyclic load patterns
that are expected in service; and

(2) Expected service deterioration,

variations in material properties, man-
ufacturing variations, and environ-
mental effects.

peller must be conducted to show that
hazardous propeller effects due to fa-
tigue will be avoided throughout the
intended operational life of the pro-
peller on either:

(1) The intended airplane by com-

plying with § 23.2400(c) or § 25.907 of this
chapter, as applicable; or

(2) A typical airplane.

[Amdt. 35–8, 73 FR 63348, Oct. 24, 2008, as
amended by Doc. FAA–2015–1621, Amdt. 35–10,
81 FR 96700, Dec. 30, 2016]

§ 35.38

Lightning strike.

The applicant must demonstrate, by

tests, analysis based on tests, or expe-
rience on similar designs, that the pro-
peller can withstand a lightning strike
without causing a major or hazardous
propeller effect. The limit to which the
propeller has been qualified must be
documented in the appropriate manu-
als. This section does not apply to

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763

Federal Aviation Administration, DOT

§ 35.41

fixed-pitch wood propellers of conven-
tional design.

[Amdt. 35–8, 73 FR 63348, Oct. 24, 2008]

§ 35.39

Endurance test.

Endurance tests on the propeller sys-

tem must be made on a representative
engine in accordance with paragraph
(a) or (b) of this section, as applicable,
without evidence of failure or malfunc-
tion.

(a) Fixed-pitch and ground adjust-

able-pitch propellers must be subjected
to one of the following tests:

(1) A 50-hour flight test in level flight

or in climb. The propeller must be op-
erated at takeoff power and rated rota-
tional speed during at least five hours
of this flight test, and at not less than
90 percent of the rated rotational speed
for the remainder of the 50 hours.

(2) A 50-hour ground test at takeoff

power and rated rotational speed.

(b) Variable-pitch propellers must be

subjected to one of the following tests:

(1) A 110-hour endurance test that

must include the following conditions:

(i) Five hours at takeoff power and

rotational speed and thirty 10-minute
cycles composed of:

(A) Acceleration from idle,
(B) Five minutes at takeoff power

and rotational speed,

uous power and rotational speed,

(iii) Fifty hours, consisting of ten 5-

hour cycles composed of:

(A) Five accelerations and decelera-

tions between idle and takeoff power
and rotational speed,

(B) Four and one half hours at ap-

proximately even incremental condi-
tions from idle up to, but not includ-
ing, maximum continuous power and
rotational speed, and

throughout the engine endurance tests
prescribed in part 33 of this chapter.

pellers of similar design may be used in
place of the tests of paragraphs (a) and
(b) of this section.

[Amdt. 35–8, 73 FR 63348, Oct. 24, 2008]

§ 35.40

Functional test.

The variable-pitch propeller system

must be subjected to the applicable
functional tests of this section. The
same propeller system used in the en-
durance test (§ 35.39) must be used in
the functional tests and must be driven
by a representative engine on a test
stand or on an airplane. The propeller
must complete these tests without evi-
dence of failure or malfunction. This
test may be combined with the endur-
ance test for accumulation of cycles.

(a) Manually-controllable propellers.

Five hundred representative flight cy-
cles must be made across the range of
pitch and rotational speed.

(b) Governing propellers. Fifteen

hundred complete cycles must be made
across the range of pitch and rota-
tional speed.

cles of feather and unfeather operation
must be made.

(d) Reversible-pitch propellers. Two

hundred complete cycles of control
must be made from lowest normal
pitch to maximum reverse pitch. Dur-
ing each cycle, the propeller must run
for 30 seconds at the maximum power
and rotational speed selected by the
applicant for maximum reverse pitch.

(e) An analysis based on tests of pro-

pellers of similar design may be used in
place of the tests of this section.

[Amdt. 35–8, 73 FR 63349, Oct. 24, 2008]

§ 35.41

Overspeed and overtorque.

(a) When the applicant seeks ap-

proval of a transient maximum pro-
peller overspeed, the applicant must
demonstrate that the propeller is capa-
ble of further operation without main-
tenance action at the maximum pro-
peller overspeed condition. This may
be accomplished by:

(1) Performance of 20 runs, each of 30

seconds duration, at the maximum pro-
peller overspeed condition; or

(2) Analysis based on test or service

experience.

(b) When the applicant seeks ap-

proval of a transient maximum pro-
peller overtorque, the applicant must

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