554 

14 CFR Ch. I (1–1–19 Edition) 

§ 27.1391 

specified in §§ 27.1391 and 27.1393, if the 
overlap intensities in relation to the 
main beam intensities do not adversely 
affect signal clarity. When the peak in-
tensity of the forward position lights is 
greater than 100 candles, the maximum 
overlap intensities between them may 
exceed the values in § 27.1395 if the 
overlap intensity in Area A is not more 
than 10 percent of peak position light 
intensity and the overlap intensity in 
Area B is not more than 2.5 percent of 
peak position light intensity. 

§ 27.1391

Minimum intensities in the 

horizontal plane of forward and 
rear position lights. 

Each position light intensity must 

equal or exceed the applicable values in 
the following table: 

Dihedral angle (light in-

cluded) 

Angle from right or left 

of longitudinal axis, 

measured from dead 

ahead 

Intensity 

(candles) 

L 

and 

R 

(forward red 

and green).

10

° 

to 10

°

...................

10

° 

to 20

°

...................

20

° 

to 110

°

.................

40 
30 

5 

A 

(rear white) ..............

110

° 

to 180

°

...............

20 

§ 27.1393

Minimum intensities in any 

vertical plane of forward and rear 
position lights. 

Each position light intensity must 

equal or exceed the applicable values in 
the following table: 

Angle above or below the horizontal plane 

Intensity, 

l 

0

°

.........................................................................

1.00 

0

° 

to 5

°

................................................................

0.90 

5

° 

to 10

°

..............................................................

0.80 

10

° 

to 15

°

............................................................

0.70 

15

° 

to 20

°

............................................................

0.50 

20

° 

to 30

°

............................................................

0.30 

30

° 

to 40

°

............................................................

0.10 

40

° 

to 90

°

............................................................

0.05 

§ 27.1395

Maximum intensities in over-

lapping beams of forward and rear 
position lights. 

No position light intensity may ex-

ceed the applicable values in the fol-
lowing table, except as provided in 
§ 27.1389(b)(3). 

Overlaps 

Maximum Intensity 

Area A 

(candles) 

Area B 

(candles) 

Green in dihedral angle 

L

.............

10 1 

Red in dihedral angle 

R

................

10 1 

Green in dihedral angle 

A

.............

5 1 

Red in dihedral angle 

A

................

5 1 

Rear white in dihedral angle 

L

......

5 1 

Overlaps 

Maximum Intensity 

Area A 

(candles) 

Area B 

(candles) 

Rear white in dihedral angle 

R

.....

5 1 

Where— 

(a) Area A includes all directions in 

the adjacent dihedral angle that pass 
through the light source and intersect 
the common boundary plane at more 
than 10 degrees but less than 20 de-
grees, and 

(b) Area B includes all directions in 

the adjacent dihedral angle that pass 
through the light source and intersect 
the common boundary plane at more 
than 20 degrees. 

§ 27.1397

Color specifications. 

Each position light color must have 

the applicable International Commis-
sion on Illumination chromaticity co-
ordinates as follows: 

(a) 

Aviation red

— 

y 

is not greater than 0.335; and 

z 

is not greater than 0.002. 

(b) 

Aviation green

— 

x 

is not greater than 0.440

¥

0.320

y

; 

x 

is not greater than 

y

¥

0.170; and 

y 

is not less than 0.390

¥

0.170

x. 

(c) 

Aviation white

— 

x 

is not less than 0.300 and not greater than 

0.540; 

y 

is not less than 

x

¥

0.040’’ or 

y

c

¥

0.010, 

whichever is the smaller; and 

y 

is not greater than 

x 

+ 0.020 nor 

0.636

¥

0.400

x

; 

Where 

y

c

is the 

y 

coordinate of the Planck-

ian radiator for the value of 

x 

considered. 

[Doc. No. 5074, 29 FR 15695, Nov. 24, 1964, as 
amended by Amdt. 27–6, 36 FR 12972, July 10, 
1971] 

§ 27.1399

Riding light. 

(a) Each riding light required for 

water operation must be installed so 
that it can— 

(1) Show a white light for at least 

two nautical miles at night under clear 
atmospheric conditions; and 

(2) Show a maximum practicable un-

broken light with the rotorcraft on the 
water. 

VerDate Sep<11>2014 

12:50 Apr 30, 2019

Jkt 247046

PO 00000

Frm 00564

Fmt 8010

Sfmt 8010

Y:\SGML\247046.XXX

247046

spaschal on DSK3GDR082PROD with CFR