March 11, 1996 FAR 23.853:
Appendix F to Part 23 — Test Procedure |
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March 11, 1996
Appendix F to Part 23: Test Procedure
Acceptable test procedure
for self-extinguishing materials for showing compliance with Secs. 23.853,
23.855 and 23.1359.
(a) Conditioning. Specimens must be conditioned to 70 degrees F,
plus or minus 5 degrees, and at 50 percent plus or minus 5 percent relative
humidity until moisture equilibrium is reached or for 24 hours. Only one
specimen at a time may be removed from the conditioning environment immediately
before subjecting it to the flame.
(b) Specimen configuration. Except as provided for materials
used in electrical wire and cable insulation and in small parts, materials must
be tested either as a 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 a test. The specimen thickness must
be no thicker than the minimum thickness to be qualified for use in the
airplane, except that:
(1) Thick foam parts, such as seat cushions, must be tested in
1/2 inch thickness;
(2) when showing compliance with Sec. 23.853(d)(3)(v) for
materials used in small parts that must be tested, the materials must be tested
in no more than 1/8 inch thickness;
(3) when showing compliance with Sec. 23.1359(c) for materials
used in electrical wire and cable insulation, the 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 conditions. When performing the tests prescribed in paragraphs (d)
and (e) of this appendix, the specimen must be mounted in a metal frame so that
(1) in the vertical tests of paragraph (d) of this appendix, the two long edges
and the upper edge are held securely; (2) in the horizontal test of paragraph
(e) of this appendix, the two long edges and the edge away from the flame are
held securely; (3) the exposed area of the specimen is at least 2 inches wide
and 12 inches long, unless the actual size used in the airplane is smaller; and
(4) 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 installed in the airplane. When
performing the test prescribed in paragraph (f) of this appendix, the specimen
must be mounted in 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.
(c) Apparatus. Except as provided in paragraph (g) of this
Appendix, tests must be conducted in a draft-free cabinet in accordance with
Federal Test Method Standard 191 Method 5903 (revised Method 5902) which is
available from the General Services Administration, Business Service Center,
Region 3, Seventh and D Streets SW., Washington, D.C. 20407, or with some other
approved equivalent method. Specimens which are too large for the cabinet must
be tested in similar draft-free conditions.
(d) Vertical test. A minimum of three specimens must be tested
and the 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 3/8 -inch I.D. tube
adjusted to give a flame of 1 1/2 inches in height. The minimum flame
temperature measured by a calibrated thermocouple pryometer in the center of the
flame must be 1550 deg. F. The lower edge of the specimen must be three- fourths
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 Secs.
23.853(d)(3)(i) and 23.853(f), the flame must be applied for 60 seconds and then
removed. For materials covered by Sec. 23.853(d)(3)(ii), the flame must be
applied for 12 seconds and then removed. Flame time, burn length, and flaming
time of drippings, if any, must be recorded. The burn length determined in
accordance with paragraph (h) of this Appendix must be measured to the nearest
one-tenth inch.
(e) 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 airplane must be face down for the test.
The specimen must be exposed to a Bunsen burner or Tirrill burner with a nominal
3/8 -inch I.D. tube adjusted to give a flame of 1 1/2 inches in height. The
minimum flame temperature measured by a calibrated thermocouple pyrometer in the
center of the flame must be 1550 deg. F. The specimen must be positioned so that
the edge being tested is three-fourths of an inch above the top of, and on the
center line of, the burner. The flame must be applied for 15 seconds and then
removed. A minimum of 10 inches of the specimen must be used for timing
purposes, approximately 1 1/2 inches must burn before the burning front reaches
the timing zone, and the average burn rate must be recorded.
(f) 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
45 degrees 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 1 1/2 inches in height. The minimum flame temperature measured by a
calibrated thermocouple pyrometer in the center of the flame must be 1550 deg.F.
Suitable precautions must be taken to avoid drafts. The flame must be applied
for 30 seconds with one-third contacting the material at the center of the
specimen and then removed. Flame time, glow time, and whether the flame
penetrates (passes through) the specimen must be recorded.
(g) Sixty-degree test. A minimum of three specimens of each wire
specification (make and size) must be tested. The specimen of wire or cable
(including insulation) must be placed at an angle of 60 degrees with the
horizontal in the cabinet specified in paragraph (c) of this appendix, with the
cabinet door open during the test or placed within a chamber approximately 2
feet high x 1 foot x 1 foot, open at the top and at one vertical side (front),
that allows sufficient flow of air for complete combustion but is free from
drafts. The specimen must be parallel to and approximately 6 inches from the
front of the chamber. The lower end of the specimen must be held rigidly
clamped. The upper end of the specimen must pass over a pulley or rod and must
have an appropriate weight attached to it so that the specimen is held tautly
throughout the flammability test. The test specimen span between lower clamp and
upper pulley or rod must be 24 inches and must be marked 8 inches from the lower
end to indicate the central point for flame application. A flame from a Bunsen
or Tirrill burner must be applied for 30 seconds at the test mark. The burner
must be mounted underneath the test mark on the specimen, perpendicular to the
specimen and at an angle of 30 degrees to the vertical plane of the specimen.
The burner must have a nominal bore of three-eighths inch, and must be adjusted
to provide a three-inch-high flame with an inner cone approximately one-third of
the flame height. The minimum temperature of the hottest portion of the flame,
as measured with a calibrated thermocouple pyrometer, may not be less than 1,750
deg.F. The burner must be positioned so that the hottest portion of the flame is
applied to the test mark on the wire. Flame time, burn length, and flaming time
drippings, if any, must be recorded. The burn length determined in accordance
with paragraph (h) of this appendix must be measured to the nearest one-tenth
inch. Breaking of the wire specimen is not considered a failure.
(h) Burn length. Burn length is the distance from the original
edge to the farthest evidence of damage to the test specimen due to flame
impingement, including areas of partial or complete consumption, charring, or
embrittlement, but not including areas sooted, stained, warped, or discolored,
nor areas where material has shrunk or melted away from the heat source.
[Amdt. 23-23, 43 FR 50594, Oct. 30, 1978, as amended by Amdt.
23-34, 52 FR 1835, Jan. 15, 1987; 52 FR 34745, Sept. 14, 1987; Amdt. 23-49, 61
FR 5170, Feb. 9, 1996]
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