840 

14 CFR Ch. I (1–1–19 Edition) 

Pt. 36, App. K 

Section K5 Trade-Offs 

If the noise evaluation measurement ex-

ceeds the noise limits described in K4 of this 
appendix at one or two measurement points: 

(a) The sum of excesses must not be great-

er than 4 EPNdB; 

(b) The excess at any single point must not 

be greater than 3 EPNdB; and 

(c) Any excess must be offset by the re-

maining noise margin at the other point or 
points. 

Section K6 Noise Certification Reference 

Procedures 

K6.1 General Conditions 

(a)–(b) [Reserved] 
(c) The takeoff, flyover and approach ref-

erence procedures must be established in ac-
cordance with sections K6.2, K6.3 and K6.4 of 

this appendix, except as specified in section 
K6.1(d) of this appendix. 

(d) If the design characteristics of the 

tiltrotor prevent test flights from being con-
ducted in accordance with section K6.2, K6.3 
or K6.4 of this appendix, the applicant must 
revise the test procedures and resubmit the 
procedures for approval. 

(e) The following reference atmospheric 

conditions must be used to establish the ref-
erence procedures: 

(1) Sea level atmospheric pressure of 2,116 

pounds per square foot (1,013.25 hPa); 

(2) Ambient air temperature of 77 

°

Fahrenheit (25 

°

Celsius, i.e. ISA + 10 

°

C); 

(3) Relative humidity of 70 percent; and 
(4) Zero wind. 
(f) For tests conducted in accordance with 

sections K6.2, K6.3, and K6.4 of this appendix, 
use the maximum normal operating RPM 

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