900
14 CFR Ch. I (1–1–14 Edition)
§ 35.7
(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
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
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