spaschal on DSK3GDR082PROD with CFR

Pt. 25, App. F

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

(3) Electrical system components. Insulation
on electrical wire or cable installed in any
area of the fuselage must be self-extinguishing when subjected to the 60 degree test
specified in part I of this appendix. The average burn length may not exceed 3 inches, and
the average flame time after removal of the
flame source may not exceed 30 seconds.
Drippings from the test specimen may not
continue to flame for more than an average
of 3 seconds after falling.
(b) Test Procedures - (1) Conditioning. Specimens must be conditioned to 70 Section5 F., and at
50 percent Section5 percent relative humidity until
moisture equilibrium is reached or for 24
hours. Each specimen must remain in the
conditioning environment until it is subjected to the flame.
(2) Specimen configuration. Except for small
parts and electrical wire and cable insulation, materials must be tested either as section cut from a fabricated part as installed
in the airplane or as a specimen simulating
a cut section, such as a specimen cut from a
flat sheet of the material or a model of the
fabricated part. The specimen may be cut
from any location in a fabricated part; however, fabricated units, such as sandwich panels, may not be separated for test. Except as
noted below, the specimen thickness must be
no thicker than the minimum thickness to
be qualified for use in the airplane. Test
specimens of thick foam parts, such as seat
cushions, must be 1-2-inch in thickness. Test
specimens of materials that must meet the
requirements of paragraph (a)(1)(v) of part I
of this appendix must be no more than 1-8inch in thickness. Electrical wire and cable
specimens must be the same size as used in
the airplane. In the case of fabrics, both the
warp and fill direction of the weave must be
tested to determine the most critical flammability condition. Specimens must be
mounted in a metal frame so that the two
long edges and the upper edge are held securely during the vertical test prescribed in
subparagraph (4) of this paragraph and the
two long edges and the edge away from the
flame are held securely during the horizontal
test prescribed in subparagraph (5) of this
paragraph. The exposed area of the specimen
must be at least 2 inches wide and 12 inches
long, unless the actual size used in the airplane is smaller. The edge to which the burner flame is applied must not consist of the
finished or protected edge of the specimen
but must be representative of the actual
cross-section of the material or part as installed in the airplane. The specimen must
be mounted in a metal frame so that all four
edges are held securely and the exposed area
of the specimen is at least 8 inches by 8
inches during the 45Section test prescribed in subparagraph (6) of this paragraph.
(3) Apparatus. Except as provided in subparagraph (7) of this paragraph, tests must
be conducted in a draft-free cabinet in ac-

cordance with Federal Test Method Standard
191 Model 5903 (revised Method 5902) for the
vertical test, or Method 5906 for horizontal
test (available from the General Services Administration, Business Service Center, Region 3, Seventh Section D Streets SW., Washington, DC 20407). Specimens which are too
large for the cabinet must be tested in similar draft-free conditions.
(4) Vertical test. A minimum of three specimens must be tested and results averaged.
For fabrics, the direction of weave corresponding to the most critical flammability
conditions must be parallel to the longest dimension. Each specimen must be supported
vertically. The specimen must be exposed to
a Bunsen or Tirrill burner with a nominal 3-8inch I.D. tube adjusted to give a flame of 11-2
inches in height. The minimum flame temperature measured by a calibrated thermocouple pyrometer in the center of the flame
must be 1550 SectionF. The lower edge of the specimen must be 3-4-inch above the top edge of
the burner. The flame must be applied to the
center line of the lower edge of the specimen.
For materials covered by paragraph (a)(1)(i)
of part I of this appendix, the flame must be
applied for 60 seconds and then removed. For
materials covered by paragraph (a)(1)(ii) of
part I of this appendix, the flame must be applied for 12 seconds and then removed. Flame
time, burn length, and flaming time of drippings, if any, may be recorded. The burn
length determined in accordance with subparagraph (7) of this paragraph must be
measured to the nearest tenth of an inch.
(5) Horizontal test. A minimum of three
specimens must be tested and the results
averaged. Each specimen must be supported
horizontally. The exposed surface, when installed in the aircraft, must be face down for
the test. The specimen must be exposed to a
Bunsen or Tirrill burner with a nominal 3-8inch I.D. tube adjusted to give a flame of 11-2
inches in height. The minimum flame temperature measured by a calibrated thermocouple pyrometer in the center of the flame
must be 1550 SectionF. The specimen must be positioned so that the edge being tested is centered 3-4-inch above the top of the burner.
The flame must be applied for 15 seconds and
then removed. A minimum of 10 inches of
specimen must be used for timing purposes,
approximately 11-2 inches must burn before
the burning front reaches the timing zone,
and the average burn rate must be recorded.
(6) Forty-five degree test. A minimum of
three specimens must be tested and the results averaged. The specimens must be supported at an angle of 45Section to a horizontal surface. The exposed surface when installed in
the aircraft must be face down for the test.
The specimens must be exposed to a Bunsen
or Tirrill burner with a nominal 3-8-inch I.D.
tube adjusted to give a flame of 11-2 inches in
height. The minimum flame temperature

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