345
Federal Aviation Administration, DOT
Pt. 23, App. 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 para-
graph (g) of this appendix, tests must be con-
ducted 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 Admin-
istration, 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 simi-
lar draft-free conditions.
(d)
Vertical test. A minimum of three speci-
mens must be tested and the results aver-
aged. For fabrics, the direction of weave cor-
responding to the most critical flammability
conditions must be parallel to the longest di-
mension. 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 tem-
perature measured by a calibrated thermo-
couple pryometer in the center of the flame
must be 1550
°
F. The lower edge of the speci-
men 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
§§ 23.853(d)(3)(i) and 23.853(f), the flame must
be applied for 60 seconds and then removed.
For materials covered by § 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 re-
corded. The burn length determined in ac-
cordance 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 in-
stalled in the airplane must be face down for
the test. The specimen must be exposed to a
Bunsen burner or Tirrill burner with a nomi-
nal
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 ther-
mocouple pyrometer in the center of the
flame must be 1550
°
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 re-
moved. A minimum of 10 inches of the speci-
men must be used for timing purposes, ap-
proximately 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 re-
sults averaged. The specimens must be sup-
ported at an angle of 45 degrees to a hori-
zontal surface. The exposed surface when in-
stalled 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 tem-
perature measured by a calibrated thermo-
couple pyrometer in the center of the flame
must be 1550
°
F. Suitable precautions must
be taken to avoid drafts. The flame must be
applied for 30 seconds with one-third con-
tacting 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 re-
corded.
(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 hor-
izontal 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
×
1 foot
×
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 at-
tached 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 un-
derneath the test mark on the specimen, per-
pendicular 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 ad-
justed to provide a three-inch-high flame
with an inner cone approximately one-third
of the flame height. The minimum tempera-
ture of the hottest portion of the flame, as
measured with a calibrated thermocouple
pyrometer, may not be less than 1,750
°
F. The
burner must be positioned so that the hot-
test 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 deter-
mined in accordance with paragraph (h) of
this appendix must be measured to the near-
est one-tenth inch. Breaking of the wire
specimen is not considered a failure.
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