758
14 CFR Ch. I (1–1–24 Edition)
§ 35.4
operating pressure, and filtration lev-
els; and
(6) State the assumptions made to
comply with the requirements of this
part.
(b) Instructions for operating the
propeller which must specify all proce-
dures necessary for operating the pro-
peller within the limitations of the
propeller type design.
[Amdt. 35–8, 73 FR 63346, Oct. 24, 2008]
§ 35.4
Instructions for Continued Air-
worthiness.
The applicant must prepare Instruc-
tions for Continued Airworthiness in
accordance with appendix A to this
part that are acceptable to the Admin-
istrator. The instructions may be in-
complete at type certification if a pro-
gram exists to ensure their completion
prior to delivery of the first aircraft
with the propeller installed, or upon
issuance of a standard certificate of
airworthiness for an aircraft with the
propeller installed, whichever occurs
later.
[Amdt. 35–5, 45 FR 60181, Sept. 11, 1980]
§ 35.5
Propeller ratings and operating
limitations.
(a) Propeller ratings and operating
limitations must:
(1) Be established by the applicant
and approved by the Administrator.
(2) Be included directly or by ref-
erence in the propeller type certificate
data sheet, as specified in § 21.41 of this
chapter.
(3) Be based on the operating condi-
tions demonstrated during the tests re-
quired by this part as well as any other
information the Administrator re-
quires as necessary for the safe oper-
ation of the propeller.
(b) Propeller ratings and operating
limitations must be established for the
following, as applicable:
(1) Power and rotational speed:
(i) For takeoff.
(ii) For maximum continuous.
(iii) If requested by the applicant,
other ratings may also be established.
(2) Overspeed and overtorque limits.
[Amdt. 35–8, 73 FR 63346, Oct. 24, 2008]
§ 35.7
Features and characteristics.
(a) The propeller may not have fea-
tures or characteristics, revealed by
any test or analysis or known to the
applicant, that make it unsafe for the
uses for which certification is re-
quested.
(b) If a failure occurs during a certifi-
cation test, the applicant must deter-
mine the cause and assess the effect on
the airworthiness of the propeller. The
applicant must make changes to the
design and conduct additional tests
that the Administrator finds necessary
to establish the airworthiness of the
propeller.
[Amdt. 35–8, 73 FR 63346, Oct. 24, 2008]
Subpart B—Design and
Construction
§ 35.11
[Reserved]
§ 35.13
[Reserved]
§ 35.15
Safety analysis.
(a)(1) The applicant must analyze the
propeller system to assess the likely
consequences of all failures that can
reasonably be expected to occur. This
analysis will take into account, if ap-
plicable:
(i) The propeller system in a typical
installation. When the analysis de-
pends on representative components,
assumed interfaces, or assumed in-
stalled conditions, the assumptions
must be stated in the analysis.
(ii) Consequential secondary failures
and dormant failures.
(iii) Multiple failures referred to in
paragraph (d) of this section, or that
result in the hazardous propeller ef-
fects defined in paragraph (g)(1) of this
section.
(2) The applicant must summarize
those failures that could result in
major propeller effects or hazardous
propeller effects defined in paragraph
(g) of this section, and estimate the
probability of occurrence of those ef-
fects.
(3) The applicant must show that
hazardous propeller effects are not pre-
dicted to occur at a rate in excess of
that defined as extremely remote
(probability of 10
¥
7
or less per propeller
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§ 35.15
flight hour). Since the estimated prob-
ability for individual failures may be
insufficiently precise to enable the ap-
plicant to assess the total rate for haz-
ardous propeller effects, compliance
may be shown by demonstrating that
the probability of a hazardous propeller
effect arising from an individual fail-
ure can be predicted to be not greater
than 10
¥
8
per propeller flight hour. In
dealing with probabilities of this low
order of magnitude, absolute proof is
not possible and reliance must be
placed on engineering judgment and
previous experience combined with
sound design and test philosophies.
(b) If significant doubt exists as to
the effects of failures or likely com-
bination of failures, the Administrator
may require assumptions used in the
analysis to be verified by test.
(c) The primary failures of certain
single propeller elements (for example,
blades) cannot be sensibly estimated in
numerical terms. If the failure of such
elements is likely to result in haz-
ardous propeller effects, those ele-
ments must be identified as propeller
critical parts. For propeller critical
parts, applicants must meet the pre-
scribed integrity specifications of
§ 35.16. These instances must be stated
in the safety analysis.
(d) If reliance is placed on a safety
system to prevent a failure progressing
to hazardous propeller effects, the pos-
sibility of a safety system failure in
combination with a basic propeller fail-
ure must be included in the analysis.
Such a safety system may include safe-
ty devices, instrumentation, early
warning devices, maintenance checks,
and other similar equipment or proce-
dures. If items of the safety system are
outside the control of the propeller
manufacturer, the assumptions of the
safety analysis with respect to the reli-
ability of these parts must be clearly
stated in the analysis and identified in
the propeller installation and oper-
ation instructions required under § 35.3.
(e) If the safety analysis depends on
one or more of the following items,
those items must be identified in the
analysis and appropriately substan-
tiated.
(1) Maintenance actions being carried
out at stated intervals. This includes
verifying that items that could fail in
a latent manner are functioning prop-
erly. When necessary to prevent haz-
ardous propeller effects, these mainte-
nance actions and intervals must be
published in the instructions for con-
tinued airworthiness required under
§ 35.4. Additionally, if errors in mainte-
nance of the propeller system could
lead to hazardous propeller effects, the
appropriate maintenance procedures
must be included in the relevant pro-
peller manuals.
(2) Verification of the satisfactory
functioning of safety or other devices
at pre-flight or other stated periods.
The details of this satisfactory func-
tioning must be published in the appro-
priate manual.
(3) The provision of specific instru-
mentation not otherwise required.
Such instrumentation must be pub-
lished in the appropriate documenta-
tion.
(4) A fatigue assessment.
(f) If applicable, the safety analysis
must include, but not be limited to, as-
sessment of indicating equipment,
manual and automatic controls, gov-
ernors and propeller control systems,
synchrophasers, synchronizers, and
propeller thrust reversal systems.
(g) Unless otherwise approved by the
Administrator and stated in the safety
analysis, the following failure defini-
tions apply to compliance with this
part.
(1) The following are regarded as haz-
ardous propeller effects:
(i) The development of excessive
drag.
(ii) A significant thrust in the oppo-
site direction to that commanded by
the pilot.
(iii) The release of the propeller or
any major portion of the propeller.
(iv) A failure that results in excessive
unbalance.
(2) The following are regarded as
major propeller effects for variable
pitch propellers:
(i) An inability to feather the pro-
peller for feathering propellers.
(ii) An inability to change propeller
pitch when commanded.
(iii) A significant uncommanded
change in pitch.
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14 CFR Ch. I (1–1–24 Edition)
§ 35.16
(iv) A significant uncontrollable
torque or speed fluctuation.
[Amdt. 35–8, 73 FR 63346, Oct. 24, 2008, as
amended by Amdt. 35–9, 78 FR 4041, Jan. 18,
2013; Amdt. 35–9A, 78 FR 45052, July 26, 2013]
§ 35.16
Propeller critical parts.
The integrity of each propeller crit-
ical part identified by the safety anal-
ysis required by § 35.15 must be estab-
lished by:
(a) A defined engineering process for
ensuring the integrity of the propeller
critical part throughout its service life,
(b) A defined manufacturing process
that identifies the requirements to
consistently produce the propeller crit-
ical part as required by the engineering
process, and
(c) A defined service management
process that identifies the continued
airworthiness requirements of the pro-
peller critical part as required by the
engineering process.
[Amdt. 35–9, 78 FR 4042, Jan. 18, 2013]
§ 35.17
Materials and manufacturing
methods.
(a) The suitability and durability of
materials used in the propeller must:
(1) Be established on the basis of ex-
perience, tests, or both.
(2) Account for environmental condi-
tions expected in service.
(b) All materials and manufacturing
methods must conform to specifica-
tions acceptable to the Administrator.
(c) The design values of properties of
materials must be suitably related to
the most adverse properties stated in
the material specification for applica-
ble conditions expected in service.
[Amdt. 35–8, 73 FR 63347, Oct. 24, 2008]
§ 35.19
Durability.
Each part of the propeller must be
designed and constructed to minimize
the development of any unsafe condi-
tion of the propeller between overhaul
periods.
§ 35.21
Variable and reversible pitch
propellers.
(a) No single failure or malfunction
in the propeller system will result in
unintended travel of the propeller
blades to a position below the in-flight
low-pitch position. The extent of any
intended travel below the in-flight low-
pitch position must be documented by
the applicant in the appropriate manu-
als. Failure of structural elements need
not be considered if the occurrence of
such a failure is shown to be extremely
remote under § 35.15.
(b) For propellers incorporating a
method to select blade pitch below the
in-flight low pitch position, provisions
must be made to sense and indicate to
the flight crew that the propeller
blades are below that position by an
amount defined in the installation
manual. The method for sensing and
indicating the propeller blade pitch po-
sition must be such that its failure
does not affect the control of the pro-
peller.
[Amdt. 35–8, 73 FR 63347, Oct. 24, 2008]
§ 35.22
Feathering propellers.
(a) Feathering propellers are in-
tended to feather from all flight condi-
tions, taking into account expected
wear and leakage. Any feathering and
unfeathering limitations must be docu-
mented in the appropriate manuals.
(b) Propeller pitch control systems
that use engine oil to feather must in-
corporate a method to allow the pro-
peller to feather if the engine oil sys-
tem fails.
(c) Feathering propellers must be de-
signed to be capable of unfeathering
after the propeller system has sta-
bilized to the minimum declared out-
side air temperature.
[Amdt. 35–8, 73 FR 63347, Oct. 24, 2008]
§ 35.23
Propeller control system.
The requirements of this section
apply to any system or component that
controls, limits or monitors propeller
functions.
(a) The propeller control system
must be designed, constructed and vali-
dated to show that:
(1) The propeller control system, op-
erating in normal and alternative oper-
ating modes and in transition between
operating modes, performs the func-
tions defined by the applicant through-
out the declared operating conditions
and flight envelope.
(2) The propeller control system
functionality is not adversely affected
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