Federal Aviation Administration, DOT

Pt. 25, App. O

TABLE 2. - FLIGHT LENGTH DISTRIBUTION - Continued
Flight length (NM)
From
7000
7200
7400
7600
7800
8000
8200
8400
8600
8800
9000
9200
9400
9600
9800

To

Airplane maximum range - nautical miles (NM)
1000

7200
7400
7600
7800
8000
8200
8400
8600
8800
9000
9200
9400
9600
9800
10000

2000

0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0

3000

0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0

0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0

4000

5000

0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0

(c) Overnight Temperature Drop. For airplanes on which FRM is installed, the overnight temperature drop for this appendix is
defined using:
(1) A temperature at the beginning of the
overnight period that equals the landing
temperature of the previous flight that is a
random value based on a Gaussian distribution; and
(2) An overnight temperature drop that is
a random value based on a Gaussian distribution.
(3) For any flight that will end with an
overnight ground period (one flight per day
out of an average number of flights per day,
depending on utilization of the particular
airplane model being evaluated), the landing
outside air temperature (OAT) is to be chosen as a random value from the following
Gaussian curve:

TABLE 3. - LANDING OUTSIDE AIR TEMPERATURE
Landing outside
air temperature SectionF

Parameter
Mean Temperature ..................................
negative 1 std dev ...................................
positive 1 std dev ....................................

58.68
20.55
13.21

(4) The outside ambient air temperature
(OAT) overnight temperature drop is to be
chosen as a random value from the following
Gaussian curve:

TABLE 4. - OUTSIDE AIR TEMPERATURE (OAT)
DROP
OAT drop
temperature SectionF

Parameter

spaschal on DSK3GDR082PROD with CFR

Mean Temp ...................................................
1 std dev ........................................................

12.0
6.0

(d) Number of Simulated Flights Required
in Analysis. In order for the Monte Carlo
analysis to be valid for showing compliance

0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0

6000
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0

7000

8000

0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0

9000

0.4
0.3
0.2
0.1
0.1
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0

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0.8
0.7
0.6
0.7
0.8
0.8
1.0
1.3
1.1
0.8
0.5
0.2
0.1
0.1
0.1

with the fleet average and warm day flammability exposure requirements, the applicant must run the analysis for a minimum
number of flights to ensure that the fleet average and warm day flammability exposure
for the fuel tank under evaluation meets the
applicable flammability limits defined in
Table 5 of this appendix.

TABLE 5. - FLAMMABILITY EXPOSURE LIMIT

Minimum number of
flights in Monte
Carlo analysis

Maximum
acceptable Monte
Carlo average fuel
tank flammability
exposure
(percent) to meet
3 percent
requirements

Maximum
acceptable Monte
Carlo average fuel
tank flammability
exposure
(percent) to meet
7 percent part 26
requirements

10,000 ....................
100,000 ..................
1,000,000 ...............

2.91
2.98
3.00

6.79
6.96
7.00

[Doc. No. FAA-2005-22997, 73 FR 42495, July
21, 2008, as amended by Doc. No. FAA-2018-
0119, Amdt. 25-145, 83 FR 9169, Mar. 5, 2018]

APPENDIX O TO PART 25 - SUPERCOOLED
LARGE DROP ICING CONDITIONS
This Appendix consists of two parts. Part I
defines this Appendix as a description of
supercooled large drop icing conditions in
which the drop median volume diameter
(MVD) is less than or greater than 40 Sectionm, the
maximum mean effective drop diameter
(MED) of Appendix C of this part continuous
maximum (stratiform clouds) icing conditions. For this Appendix, supercooled large
drop icing conditions consist of freezing drizzle and freezing rain occurring in and/or
below stratiform clouds. Part II defines ice
accretions used to show compliance with the
airplane performance and handling qualities
requirements of subpart B of this part.

459

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10000

0.7
0.5
0.5
0.5
0.6
0.5
0.5
0.6
0.4
0.2
0.0
0.0
0.0
0.0
0.0

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