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740 

14 CFR Ch. I (1–1–19 Edition) 

Pt. 33, App. B 

tests or equivalent service engine test expe-
rience on engines of similar design and eval-
uations 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] 

A

PPENDIX

TO

P

ART

33—C

ERTIFICATION

 

S

TANDARD

A

TMOSPHERIC

C

ON

-

CENTRATIONS OF

R

AIN AND

H

AIL

 

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 accord-
ance with the requirements of § 33.78(a)(2). In 
conducting tests, normally by spraying liq-
uid water to simulate rain conditions and by 
delivering hail fabricated from ice to simu-
late hail conditions, the use of water drop-
lets and hail having shapes, sizes and dis-
tributions 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 se-
verity of the test. 

T

ABLE

B1—C

ERTIFICATION

S

TANDARD

 

A

TMOSPHERIC

R

AIN

C

ONCENTRATIONS

 

Altitude (feet) 

Rain water content (RWC) 

(grams water/meter

3

air) 

0 .................................................

20.0 

20,000 ........................................

20.0 

26,300 ........................................

15.2 

32,700 ........................................

10.8 

39,300 ........................................

7.7 

46,000 ........................................

5.2 

RWC values at other altitudes may be determined by linear 

interpolation. 

N

OTE

: Source of data—Results of the Aerospace Industries 

Association (AIA) Propulsion Committee Study, Project PC 
338–1, June 1990. 

T

ABLE

B2—C

ERTIFICATION

S

TANDARD

 

A

TMOSPHERIC

H

AIL

C

ONCENTRATIONS

 

Altitude (feet) 

Hail water content (HWC) 

(grams water/meter

3

air) 

0 .................................................

6.0 

7,300 ..........................................

8.9 

8,500 ..........................................

9.4 

10,000 ........................................

9.9 

12,000 ........................................

10.0 

15,000 ........................................

10.0 

16,000 ........................................

8.9 

17,700 ........................................

7.8 

19,300 ........................................

6.6 

21,500 ........................................

5.6 

24,300 ........................................

4.4 

29,000 ........................................

3.3 

46,000 ........................................

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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