410 

14 CFR Ch. I (1–1–19 Edition) 

Pt. 25, App. F 

the specimen must be the same as that of the 
aircraft component it represents up to a 
maximum thickness of 1.75 inches (45 mm). 
Test specimens representing thicker compo-
nents must be 1.75 inches (45 mm). 

(2) 

Conditioning. 

Specimens must be condi-

tioned as described in Part 1 of this appen-
dix. 

(3) 

Mounting. 

Each test specimen must be 

wrapped tightly on all sides of the specimen, 
except for the one surface that is exposed 
with a single layer of .001 inch (.025 mm) alu-
minum foil. 

(e) 

Procedure. 

(1) The power supply to the 

radiant panel must be set to produce a radi-
ant flux of 3.5 

±

.05 W/cm

2

, as measured at the 

point the center of the specimen surface will 
occupy when positioned for the test. The ra-
diant flux must be measured after the air 
flow through the equipment is adjusted to 
the desired rate. 

(2) After the pilot flames are lighted, their 

position must be checked as described in 
paragraph (b)(8) of this part IV. 

(3) Air flow through the apparatus must be 

controlled by a circular plate orifice located 
in a 1.5 inch (38.1 mm) I.D. pipe with two 
pressure measuring points, located 1.5 inches 
(38 mm) upstream and .75 inches (19 mm) 
downstream of the orifice plate. The pipe 
must be connected to a manometer set at a 
pressure differential of 7.87 inches (200 mm) 
of Hg. (See Figure 1B of this part IV.) The 
total air flow to the equipment is approxi-
mately .04 m

3

/seconds. The stop on the 

vertical specimen holder rod must be ad-
justed so that the exposed surface of the 
specimen is positioned 3.9 inches (100 mm) 
from the entrance when injected into the en-
vironmental chamber. 

(4) The specimen must be placed in the 

hold chamber with the radiation doors 
closed. The airtight outer door must be se-
cured, and the recording devices must be 
started. The specimen must be retained in 
the hold chamber for 60 seconds, plus or 
minus 10 seconds, before injection. The ther-
mopile ‘‘zero’’ value must be determined dur-
ing the last 20 seconds of the hold period. 
The sample must not be injected before com-
pletion of the ‘‘zero’’ value determination. 

(5) When the specimen is to be injected, the 

radiation doors must be opened. After the 
specimen is injected into the environmental 
chamber, the radiation doors must be closed 
behind the specimen. 

(6) [Reserved] 
(7) Injection of the specimen and closure of 

the inner door marks time zero. A record of 
the thermopile output with at least one data 
point per second must be made during the 
time the specimen is in the environmental 
chamber. 

(8) The test duration is five minutes. The 

lower pilot burner and the upper pilot burner 
must remain lighted for the entire duration 
of the test, except that there may be inter-
mittent flame extinguishment for periods 
that do not exceed 3 seconds. Furthermore, if 
the optional three-hole upper burner is used, 
at least two flamelets must remain lighted 
for the entire duration of the test, except 
that there may be intermittent flame extin-
guishment of all three flamelets for periods 
that do not exceed 3 seconds. 

(9) A minimum of three specimens must be 

tested. 

(f) 

Calculations. 

(1) The calibration factor is 

calculated as follows: 

K

F

F

V

V

k

mole

T

P

P

mole CH STP

WATT

kcal

kw

w

h

O

O

cal

a

v

=

−

(

)

−

(

)

×

−

(

)

×

×

−

×

×

×

1

1

210 8

22

273

760

4

22

01433

1000

.

.41

min

.

 

 

F

0

= flow of methane at baseline (1pm) 

F

1

= higher preset flow of methane (1pm) 

V

0

= thermopile voltage at baseline (mv) 

V

1

= thermopile voltage at higher flow (mv) 

T

a

= Ambient temperature (K) 

P = Ambient pressure (mm Hg) 
P

v

= Water vapor pressure (mm Hg) 

(2) Heat release rates may be calculated 

from the reading of the thermopile output 
voltage at any instant of time as: 

HRR

V

V

K

m

m

b

n

=

−

(

)

.02323

2

HRR = heat release rate (kw/m

2

) 

V

b

= baseline voltage (mv) 

V

m

= measured thermopile voltage (mv) 

K

h

= calibration factor (kw/mv) 

(3) The integral of the heat release rate is 

the total heat release as a function of time 
and is calculated by multiplying the rate by 
the data sampling frequency in minutes and 
summing the time from zero to two minutes. 

(g) 

Criteria. 

The total positive heat release 

over the first two minutes of exposure for 
each of the three or more samples tested 
must be averaged, and the peak heat release 
rate for each of the samples must be aver-
aged. The average total heat release must 
not exceed 65 kilowatt-minutes per square 
meter, and the average peak heat release 
rate must not exceed 65 kilowatts per square 
meter. 

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