395 

Federal Aviation Administration, DOT 

Pt. 25, App. F 

measured by a calibrated thermocouple py-
rometer 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 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. 

(7) 

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

° 

with the horizontal 

in the cabinet specified in subparagraph (3) 
of this paragraph with the cabinet door open 
during the test, or must be placed within a 
chamber approximately 2 feet high by 1 foot 
by 1 foot, open at the top and at one vertical 
side (front), and which allows sufficient flow 
of air for complete combustion, but which is 
free from drafts. The specimen must be par-
allel 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 mount-
ed underneath the test mark on the speci-
men, perpendicular to the specimen and at 
an angle of 30

° 

to the vertical plane of the 

specimen. The burner must have a nominal 
bore of 

3

⁄

8

-inch and be adjusted to provide a 

3-inch high flame with an inner cone ap-
proximately 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 1750 

°

F. The burner must be posi-

tioned so that the hottest portion of the 
flame is applied to the test mark on the 
wire. Flame time, burn length, and flaming 
time of drippings, if any, must be recorded. 
The burn length determined in accordance 
with paragraph (8) of this paragraph must be 
measured to the nearest tenth of an inch. 
Breaking of the wire specimens is not consid-
ered a failure. 

(8) 

Burn length. 

Burn length is the distance 

from the original edge to the farthest evi-
dence of damage to the test specimen due to 
flame impingement, including areas of par-
tial or complete consumption, charring, or 
embrittlement, but not including areas soot-
ed, stained, warped, or discolored, nor areas 
where material has shrunk or melted away 
from the heat source. 

Part II—Flammability of Seat Cushions 

(a) 

Criteria for Acceptance. 

Each seat cush-

ion must meet the following criteria: 

(1) At least three sets of seat bottom and 

seat back cushion specimens must be tested. 

(2) If the cushion is constructed with a fire 

blocking material, the fire blocking material 
must completely enclose the cushion foam 
core material. 

(3) Each specimen tested must be fab-

ricated using the principal components (i.e., 
foam core, flotation material, fire blocking 
material, if used, and dress covering) and as-
sembly processes (representative seams and 
closures) intended for use in the production 
articles. If a different material combination 
is used for the back cushion than for the bot-
tom cushion, both material combinations 
must be tested as complete specimen sets, 
each set consisting of a back cushion speci-
men and a bottom cushion specimen. If a 
cushion, including outer dress covering, is 
demonstrated to meet the requirements of 
this appendix using the oil burner test, the 
dress covering of that cushion may be re-
placed with a similar dress covering provided 
the burn length of the replacement covering, 
as determined by the test specified in 
§ 25.853(c), does not exceed the corresponding 
burn length of the dress covering used on the 
cushion subjected to the oil burner test. 

(4) For at least two-thirds of the total 

number of specimen sets tested, the burn 
length from the burner must not reach the 
side of the cushion opposite the burner. The 
burn length must not exceed 17 inches. Burn 
length is the perpendicular distance from the 
inside edge of the seat frame closest to the 
burner to the farthest evidence of damage to 
the test specimen due to flame impingement, 
including areas of partial or complete con-
sumption, charring, or embrittlement, but 
not including areas sooted, stained, warped, 
or discolored, or areas where material has 
shrunk or melted away from the heat source. 

(5) The average percentage weight loss 

must not exceed 10 percent. Also, at least 
two-thirds of the total number of specimen 
sets tested must not exceed 10 percent 
weight loss. All droppings falling from the 
cushions and mounting stand are to be dis-
carded before the after-test weight is deter-
mined. The percentage weight loss for a spec-
imen set is the weight of the specimen set 
before testing less the weight of the speci-
men set after testing expressed as the per-
centage of the weight before testing. 

(b) 

Test Conditions. 

Vertical air velocity 

should average 25 fpm

±

10 fpm at the top of 

the back seat cushion. Horizontal air veloc-
ity should be below 10 fpm just above the 
bottom seat cushion. Air velocities should be 
measured with the ventilation hood oper-
ating and the burner motor off. 

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