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Federal Aviation Administration, DOT
§ 25.613
design detail and part must be estab-
lished by tests.
§ 25.603
Materials.
The suitability and durability of ma-
terials used for parts, the failure of
which could adversely affect safety,
must—
(a) Be established on the basis of ex-
perience or tests;
(b) Conform to approved specifica-
tions (such as industry or military
specifications, or Technical Standard
Orders) 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 tem-
perature and humidity, expected in
service.
[Doc. No. 5066, 29 FR 18291, Dec. 24, 1964, as
amended by Amdt. 25–38, 41 FR 55466, Dec. 20,
1976; Amdt. 25–46, 43 FR 50595, Oct. 30, 1978]
§ 25.605
Fabrication methods.
(a) The methods of fabrication used
must produce a consistently sound
structure. If a fabrication process (such
as gluing, spot welding, or heat treat-
ing) requires close control to reach this
objective, the process must be per-
formed under an approved process spec-
ification.
(b) Each new aircraft fabrication
method must be substantiated by a
test program.
[Doc. No. 5066, 29 FR 18291, Dec. 24, 1964, as
amended by Amdt. 25–46, 43 FR 50595, Oct. 30,
1978]
§ 25.607
Fasteners.
(a) Each removable bolt, screw, nut,
pin, or other removable fastener must
incorporate two separate locking de-
vices if—
(1) Its loss could preclude continued
flight and landing within the design
limitations of the airplane using nor-
mal pilot skill and strength; or
(2) Its loss could result in reduction
in pitch, yaw, or roll control capability
or response below that required by
Subpart B of this chapter.
(b) The fasteners specified in para-
graph (a) of this section and their lock-
ing devices may not be adversely af-
fected by the environmental conditions
associated with the particular installa-
tion.
(c) No self-locking nut may be used
on any bolt subject to rotation in oper-
ation unless a nonfriction locking de-
vice is used in addition to the self-lock-
ing device.
[Amdt. 25–23, 35 FR 5674, Apr. 8, 1970]
§ 25.609
Protection of structure.
Each part of the structure must—
(a) Be suitably protected against de-
terioration or loss of strength in serv-
ice due to any cause, including—
(1) Weathering;
(2) Corrosion; and
(3) Abrasion; and
(b) Have provisions for ventilation
and drainage where necessary for pro-
tection.
§ 25.611
Accessibility provisions.
(a)Means must be provided to allow
inspection (including inspection of
principal structural elements and con-
trol systems), replacement of parts
normally requiring replacement, ad-
justment, and lubrication as necessary
for continued airworthiness. The in-
spection means for each item must be
practicable for the inspection interval
for the item. Nondestructive inspection
aids may be used to inspect structural
elements where it is impracticable to
provide means for direct visual inspec-
tion if it is shown that the inspection
is effective and the inspection proce-
dures are specified in the maintenance
manual required by § 25.1529.
(b) EWIS must meet the accessibility
requirements of § 25.1719.
[Amdt. 25–23, 35 FR 5674, Apr. 8, 1970, as
amended by Amdt. 25–123, 72 FR 63404, Nov. 8,
2007]
§ 25.613
Material strength properties
and material design values.
(a) Material strength properties must
be based on enough tests of material
meeting approved specifications to es-
tablish design values on a statistical
basis.
(b) Material design values must be
chosen to minimize the probability of
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