837 

Federal Aviation Administration, DOT 

Pt. 36, App. K 

A

PPENDIX

K 

TO

P

ART

36—N

OISE

R

E

-

QUIREMENTS FOR

T

ILTROTORS

U

NDER

 

S

UBPART

K 

K1 

General 

K2 

Noise Evaluation Measure 

K3 

Noise Measurement Reference Points 

K4 

Noise Limits 

K5 

Trade-offs 

K6 

Noise Certification Reference Procedures 

K7 

Test Procedures 

Section K1 General 

This appendix prescribes noise limits and 

procedures for measuring noise and adjusting 
the data to standard conditions for tiltrotors 
as specified in § 36.1 of this part. 

Section K2 Noise Evaluation Measure 

The noise evaluation measure is the effec-

tive perceived noise level in EPNdB, to be 
calculated in accordance with section A36.4 
of Appendix A to this part, except correc-
tions for spectral irregularities must be de-
termined using the 50 Hz sound pressure 
level found in section H36.201 of Appendix H 
to this part. 

Section K3 Noise Measurement Reference Points 

The following noise reference points must 

be used when demonstrating tiltrotor com-
pliance with section K6 (Noise Certification 
Reference Procedures) and section K7 (Test 
Procedures) of this appendix: 

(a) 

Takeoff reference noise measurement 

points

— 

As shown in Figure K1 below: 
(1) The centerline noise measurement 

flight path reference point, designated A, is 
located on the ground vertically below the 
reference takeoff flight path. The measure-
ment point is located 1,640 feet (500 m) in the 
horizontal direction of flight from the point 
Cr where transition to climbing flight is ini-
tiated, as described in section K6.2 of this ap-
pendix; 

(2) Two sideline noise measurement points, 

designated as S(starboard) and S(port), are 
located on the ground perpendicular to and 
symmetrically stationed at 492 feet (150 m) 
on each side of the takeoff reference flight 
path. The measurement points bisect the 
centerline flight path reference point A. 

(b) 

Flyover reference noise measurement 

points

— 

As shown in Figure K2 below: 

(1) The centerline noise measurement 

flight path reference point, designated A, is 
located on the ground 492 feet (150 m) 
vertically below the reference flyover flight 

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