spaschal on DSK3GDR082PROD with CFR

Section 27.601

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

required by paragraph (d)(1)(iv) of this
section that may occur from fatigue or
other in-service causes before such
damage has grown to the extent that
the component cannot sustain the required residual strength capability. In
establishing these inspection intervals,
the following items must be considered:
(A) The growth rate, including nogrowth, of the damage under the repeated loads expected in-service determined by tests or analysis supported
by tests;
(B) The required residual strength for
the assumed damage established after
considering the damage type, inspection interval, detectability of damage,
and the techniques adopted for damage
detection. The minimum required residual strength is limit load; and
(C) Whether the inspection will detect the damage growth before the
minimum residual strength is reached
and restored to ultimate load capability, or whether the component will
require replacement.
(3) Each applicant must consider the
effects of damage on stiffness, dynamic
behavior, loads, and functional performance on all PSEs when substantiating the maximum assumed damage
size and inspection interval.
(e) Fatigue Evaluation: If an applicant establishes that the damage tolerance evaluation described in paragraph
(d) of this section is impractical within
the limits of geometry, inspectability,
or good design practice, the applicant
must do a fatigue evaluation of the
particular composite rotorcraft structure and:
(1) Identify all PSEs considered in
the fatigue evaluation;
(2) Identify the types of damage for
all PSEs considered in the fatigue evaluation;
(3) Establish supplemental procedures to minimize the risk of catastrophic failure associated with the
damages identified in paragraph (d) of
this section; and
(4) Include these supplemental procedures in the Airworthiness Limitations
section of the Instructions for Continued Airworthiness required by Section 27.1529.
[Doc. No. FAA-2009-0660, Amdt. 27-47, 76 FR
74663, Dec. 1, 2011]

Subpart D - Design and
Construction
GENERAL
Section 27.601

Design.

(a) The rotorcraft may have no design features or details that experience
has shown to be hazardous or unreliable.
(b) The suitability of each questionable design detail and part must be established by tests.
Section 27.602

Critical parts.

(a) Critical part. A critical part is a
part, the failure of which could have a
catastrophic effect upon the rotocraft,
and for which critical characteristics
have been identified which must be
controlled to ensure the required level
of integrity.
(b) If the type design includes crtical
parts, a critical parts list shall be established. Procedures shall be established to define the critical design
characteristics, identify processes that
affect those characteristics, and identify the design change and process
change controls necessary for showing
compliance with the quality assurance
requirements of part 21 of this chapter.
[Doc. No. 29311, 64 FR 46232, Aug. 24, 1999]

Section 27.603

Materials.

The suitability and durability of materials used for parts, the failure of
which could adversely affect safety,
must - 
(a) Be established on the basis of experience or tests;
(b) Meet approved specifications that
ensure their having the strength and
other properties assumed in the design
data; and
(c) Take into account the effects of
environmental conditions, such as temperature and humidity, expected in
service.
(Secs. 313(a), 601, 603, 604, Federal Aviation
Act of 1958 (49 U.S.C. 1354(a), 1421, 1423, 1424);
and sec. 6(c) of the Dept. of Transportation
Act (49 U.S.C. 1655(c)))
[Doc. No. 5074, 29 FR 15695, Nov. 24, 1964, as
amended by Amdt. 27-11, 41 FR 55469, Dec. 20,
1976; Amdt. 27-16, 43 FR 50599, Oct. 30, 1978]

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