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761 

Federal Aviation Administration, DOT 

§ 35.34 

by the declared environmental condi-
tions, including temperature, electro-
magnetic interference (EMI), high in-
tensity radiated fields (HIRF) and 
lightning. The environmental limits to 
which the system has been satisfac-
torily validated must be documented in 
the appropriate propeller manuals. 

(3) A method is provided to indicate 

that an operating mode change has oc-
curred if flight crew action is required. 
In such an event, operating instruc-
tions must be provided in the appro-
priate manuals. 

(b) The propeller control system 

must be designed and constructed so 
that, in addition to compliance with 
§ 35.15: 

(1) No single failure or malfunction of 

electrical or electronic components in 
the control system results in a haz-
ardous propeller effect. 

(2) Failures or malfunctions directly 

affecting the propeller control system 
in a typical airplane, such as struc-
tural failures of attachments to the 
control, fire, or overheat, do not lead 
to a hazardous propeller effect. 

(3) The loss of normal propeller pitch 

control does not cause a hazardous pro-
peller effect under the intended oper-
ating conditions. 

(4) The failure or corruption of data 

or signals shared across propellers does 
not cause a hazardous propeller effect. 

(c) Electronic propeller control sys-

tem imbedded software must be de-
signed and implemented by a method 
approved by the Administrator that is 
consistent with the criticality of the 
performed functions and that mini-
mizes the existence of software errors. 

(d) The propeller control system 

must be designed and constructed so 
that the failure or corruption of air-
plane-supplied data does not result in 
hazardous propeller effects. 

(e) The propeller control system 

must be designed and constructed so 
that the loss, interruption or abnormal 
characteristic of airplane-supplied 
electrical power does not result in haz-
ardous propeller effects. The power 
quality requirements must be described 
in the appropriate manuals. 

[Amdt. 35–8, 73 FR 63347, Oct. 24, 2008] 

§ 35.24

Strength. 

The maximum stresses developed in 

the propeller may not exceed values ac-
ceptable to the Administrator consid-
ering the particular form of construc-
tion and the most severe operating 
conditions. 

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

Subpart C—Tests and Inspections 

§ 35.31

[Reserved] 

§ 35.33

General. 

(a) Each applicant must furnish test 

article(s) and suitable testing facili-
ties, including equipment and com-
petent personnel, and conduct the re-
quired tests in accordance with part 21 
of this chapter. 

(b) All automatic controls and safety 

systems must be in operation unless it 
is accepted by the Administrator as 
impossible or not required because of 
the nature of the test. If needed for 
substantiation, the applicant may test 
a different propeller configuration if 
this does not constitute a less severe 
test. 

(c) Any systems or components that 

cannot be adequately substantiated by 
the applicant to the requirements of 
this part are required to undergo addi-
tional tests or analysis to demonstrate 
that the systems or components are 
able to perform their intended func-
tions in all declared environmental and 
operating conditions. 

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

§ 35.34

Inspections, adjustments and 

repairs. 

(a) Before and after conducting the 

tests prescribed in this part, the test 
article must be subjected to an inspec-
tion, and a record must be made of all 
the relevant parameters, calibrations 
and settings. 

(b) During all tests, only servicing 

and minor repairs are permitted. If 
major repairs or part replacement is 
required, the Administrator must ap-
prove the repair or part replacement 

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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. 

(c) Components used with or attached 

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. 

(c) A fatigue evaluation of the pro-

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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