Section 35.16

14 CFR Ch. I (1-1-19 Edition)

(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]

Section 35.16 Propeller critical parts.
The integrity of each propeller critical part identified by the safety analysis required by Section 35.15 must be established 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 critical part as required by the engineering
process, and
(c) A defined service management
process that identifies the continued
airworthiness requirements of the propeller critical part as required by the
engineering process.
[Amdt. 35-9, 78 FR 4042, Jan. 18, 2013]

Section 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 experience, tests, or both.
(2) Account for environmental conditions expected in service.
(b) All materials and manufacturing
methods must conform to specifications 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 applicable conditions expected in service.
[Amdt. 35-8, 73 FR 63347, Oct. 24, 2008]

spaschal on DSK3GDR082PROD with CFR

Section 35.19 Durability.
Each part of the propeller must be
designed and constructed to minimize
the development of any unsafe condition of the propeller between overhaul
periods.
Section 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 lowpitch position must be documented by
the applicant in the appropriate manuals. Failure of structural elements need
not be considered if the occurrence of
such a failure is shown to be extremely
remote under Section 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 position must be such that its failure
does not affect the control of the propeller.
[Amdt. 35-8, 73 FR 63347, Oct. 24, 2008]

Section 35.22

Feathering propellers.

(a) Feathering propellers are intended to feather from all flight conditions, taking into account expected
wear and leakage. Any feathering and
unfeathering limitations must be documented in the appropriate manuals.
(b) Propeller pitch control systems
that use engine oil to feather must incorporate a method to allow the propeller to feather if the engine oil system fails.
(c) Feathering propellers must be designed to be capable of unfeathering
after the propeller system has stabilized to the minimum declared outside air temperature.
[Amdt. 35-8, 73 FR 63347, Oct. 24, 2008]

Section 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 validated to show that:
(1) The propeller control system, operating in normal and alternative operating modes and in transition between
operating modes, performs the functions defined by the applicant throughout the declared operating conditions
and flight envelope.
(2) The propeller control system
functionality is not adversely affected

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