Federal Aviation Administration, DOT

Section 27.653

(i) The strength requirements of
Section 27.305 at an ultimate load corresponding to a casting factor of 1.25;
and
(ii) The deformation requirements of
Section 27.305 at a load of 1.15 times the limit
load.
(d) Noncritical castings. For each casting other than those specified in paragraph (c) of this section, the following
apply:
(1) Except as provided in paragraphs
(d)(2) and (3) of this section, the casting
factors and corresponding inspections
must meet the following table:
Casting factor

Inspection

2.0 or greater ...............
Less than 2.0, greater
than 1.5.

100 percent visual.
100 percent visual, and magnetic
particle (ferromagnetic materials),
penetrant (nonferromagnetic materials), or approved equivalent
inspection methods.
100 percent visual, and magnetic
particle (ferromagnetic materials).
penetrant (nonferromagnetic materials), and radiographic or approved
equivalent
inspection
methods.

1.25 through 1.50 ........

(2) The percentage of castings inspected by nonvisual methods may be
reduced below that specified in paragraph (d)(1) of this section when an approved quality control procedure is established.
(3) For castings procured to a specification that guarantees the mechanical properties of the material in the
casting and provides for demonstration
of these properties by test of coupons
cut from the castings on a sampling
basis - 
(i) A casting factor of 1.0 may be
used; and
(ii) The castings must be inspected as
provided in paragraph (d)(1) of this section for casting factors of  - 1.25 through
1.50 -  and tested under paragraph (c)(2)
of this section.
[Doc. No. 5074, 29 FR 15695, Nov. 24, 1964, as
amended by Amdt. 27-34, 62 FR 46173, Aug. 29,
1997]

spaschal on DSK3GDR082PROD with CFR

Section 27.623

Bearing factors.

(a) Except as provided in paragraph
(b) of this section, each part that has
clearance (free fit), and that is subject
to pounding or vibration, must have a
bearing factor large enough to provide

for the effects of normal relative motion.
(b) No bearing factor need be used on
a part for which any larger special factor is prescribed.
Section 27.625 Fitting factors.
For each fitting (part or terminal
used to join one structural member to
another) the following apply:
(a) For each fitting whose strength is
not proven by limit and ultimate load
tests in which actual stress conditions
are simulated in the fitting and surrounding structures, a fitting factor of
at least 1.15 must be applied to each
part of - 
(1) The fitting;
(2) The means of attachment; and
(3) The bearing on the joined members.
(b) No fitting factor need be used - 
(1) For joints made under approved
practices and based on comprehensive
test data (such as continuous joints in
metal plating, welded joints, and scarf
joints in wood); and
(2) With respect to any bearing surface for which a larger special factor is
used.
(c) For each integral fitting, the part
must be treated as a fitting up to the
point at which the section properties
become typical of the member.
(d) Each seat, berth, litter, safety
belt, and harness attachment to the
structure must be shown by analysis,
tests, or both, to be able to withstand
the
inertia
forces
prescribed
in
Section 27.561(b)(3) multiplied by a fitting factor of 1.33.
[Doc. No. 5074, 29 FR 15695, Nov. 24, 1964, as
amended by Amdt. 27-35, 63 FR 43285, Aug. 12,
1998]

Section 27.629 Flutter.
Each aerodynamic surface of the
rotorcraft must be free from flutter
under each appropriate speed and
power condition.
[Doc. No. 5074, 29 FR 15695, Nov. 24, 1964, as
amended by Amdt. 27-26, 55 FR 8000, Mar. 6,
1990]

ROTORS
Section 27.653 Pressure venting and drainage of rotor blades.
(a) For each rotor blade - 

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