Pt. 33, App. B

14 CFR Ch. I (1-1-19 Edition)

tests or equivalent service engine test experience on engines of similar design and evaluations of service usage of the 30-second OEI
or 2-minute OEI ratings.
[Amdt. 33-9, 45 FR 60181, Sept. 11, 1980, as
amended by Amdt. 33-13, 54 FR 34330, Aug. 18,
1989; Amdt. 33-21, 72 FR 1878, Jan. 16, 2007;
Amdt. 33-25, 73 FR 48124, Aug. 18, 2008]

APPENDIX B TO PART 33 - CERTIFICATION
STANDARD
ATMOSPHERIC
CONCENTRATIONS OF RAIN AND HAIL
Figure B1, Table B1, Table B2, Table B3,
and Table B4 specify the atmospheric con-

centrations and size distributions of rain and
hail for establishing certification, in accordance with the requirements of Section 33.78(a)(2). In
conducting tests, normally by spraying liquid water to simulate rain conditions and by
delivering hail fabricated from ice to simulate hail conditions, the use of water droplets and hail having shapes, sizes and distributions of sizes other than those defined
in this appendix B, or the use of a single size
or shape for each water droplet or hail, can
be accepted, provided that applicant shows
that the substitution does not reduce the severity of the test.

TABLE B1 - CERTIFICATION STANDARD
ATMOSPHERIC RAIN CONCENTRATIONS

TABLE B2 - CERTIFICATION STANDARD
ATMOSPHERIC HAIL CONCENTRATIONS

Rain water content (RWC)
(grams water/meter 3 air)

Altitude (feet)
0 .................................................
20,000 ........................................
26,300 ........................................
32,700 ........................................
39,300 ........................................
46,000 ........................................

20.0
20.0
15.2
10.8
7.7
5.2

Hail water content (HWC)
(grams water/meter 3 air)

0 .................................................
7,300 ..........................................
8,500 ..........................................
10,000 ........................................
12,000 ........................................
15,000 ........................................
16,000 ........................................
17,700 ........................................
19,300 ........................................
21,500 ........................................
24,300 ........................................
29,000 ........................................
46,000 ........................................

6.0
8.9
9.4
9.9
10.0
10.0
8.9
7.8
6.6
5.6
4.4
3.3
0.2

HWC values at other altitudes may be determined by linear
interpolation. The hail threat below 7,300 feet and above
29,000 feet is based on linearly extrapolated data.

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RWC values at other altitudes may be determined by linear
interpolation.
NOTE: Source of data - Results of the Aerospace Industries
Association (AIA) Propulsion Committee Study, Project PC
338-1, June 1990.

Altitude (feet)