370 

14 CFR Ch. I (1–1–19 Edition) 

Pt. 60, App. C 

to the flight crew. These aural cues can ei-
ther assist the crew (as an indication of an 
abnormal situation), or hinder the crew (as a 
distraction or nuisance). For effective train-
ing, the flight simulator should provide 
flight deck sounds that are perceptible to the 
pilot during normal and abnormal oper-
ations, and that are comparable to those of 
the helicopter. The flight simulator operator 
should carefully evaluate background noises 
in the location where the device will be in-
stalled. To demonstrate compliance with the 
sound requirements, the objective or valida-
tion tests in this attachment were selected 
to provide a representative sample of normal 
static conditions typically experienced by a 
pilot. 

b. Alternate propulsion. For FFS with 

multiple propulsion configurations, any con-
dition listed in Table C2A in this attachment 
should be presented for evaluation as part of 
the QTG if identified by the helicopter man-
ufacturer or other data supplier as signifi-
cantly different due to a change in propul-
sion system (engine or propeller). 

c. Data and Data Collection System. 
(1) Information provided to the flight simu-

lator manufacturer should comply be pre-
sented in the format suggested by the 
‘‘International Air Transport Association 
(IATA) Flight Simulator Design and Per-
formance Data Requirements,’’ as amended. 
This information should contain calibration 
and frequency response data. 

(2) The system used to perform the tests 

listed in Table C2A should comply with the 
following standards: 

(a) The specifications for octave, half oc-

tave, and third octave band filter sets may 
be found in American National Standards In-
stitute (ANSI) S1.11–1986. 

(b) Measurement microphones should be 

type WS2 or better, as described in Inter-
national Electrotechnical Commission (IEC) 
1094–4–1995. 

(3) Headsets. If headsets are used during 

normal operation of the helicopter they 
should also be used during the flight simu-
lator evaluation. 

(4) Playback equipment. Playback equip-

ment and recordings of the QTG conditions 
should be provided during initial evalua-
tions. 

(5) Background noise. 
(a) Background noise is the noise in the 

flight simulator that is not associated with 
the helicopter, but is caused by the flight 
simulator’s cooling and hydraulic systems 
and extraneous noise from other locations in 
the building. Background noise can seriously 
impact the correct simulation of helicopter 
sounds, and should be kept below the heli-
copter sounds. In some cases, the sound level 
of the simulation can be increased to com-
pensate for the background noise. However, 
this approach is limited by the specified tol-
erances and by the subjective acceptability 

of the sound environment to the evaluation 
pilot. 

(b) The acceptability of the background 

noise levels is dependent upon the normal 
sound levels in the helicopter being rep-
resented. Background noise levels that fall 
below the lines defined by the following 
points, may be acceptable: 

(i) 70 dB @ 50 Hz; 
(ii) 55 dB @ 1000 Hz; 
(iii) 30 dB @ 16 kHz. 
(N

OTE

: These limits are for unweighted 

1

⁄

3

 

octave band sound levels. Meeting these lim-
its for background noise does not ensure an 
acceptable flight simulator. Helicopter 
sounds that fall below this limit require 
careful review and may require lower limits 
on background noise.) 

(6) Validation testing. Deficiencies in heli-

copter recordings should be considered when 
applying the specified tolerances to ensure 
that the simulation is representative of the 
helicopter. Examples of typical deficiencies 
are: 

(a) Variation of data between tail numbers. 
(b) Frequency response of microphones. 
(c) Repeatability of the measurements. 

T

ABLE

C2C—E

XAMPLE OF

C

ONTINUING

Q

UALI

-

FICATION

F

REQUENCY

R

ESPONSE

T

EST

T

OL

-

ERANCE

 

Band center 

frequency 

Initial results 

(dBSPL) 

Continuing 

qualification 

results 

(dBSPL) 

Absolute 

difference 

50 .....................

75.0 73.8 1.2 

63 .....................

75.9 75.6 0.3 

80 .....................

77.1 76.5 0.6 

100 ...................

78.0 78.3 0.3 

125 ...................

81.9 81.3 0.6 

160 ...................

79.8 80.1 0.3 

200 ...................

83.1 84.9 1.8 

250 ...................

78.6 78.9 0.3 

315 ...................

79.5 78.3 1.2 

400 ...................

80.1 79.5 0.9 

500 ...................

80.7 79.8 0.9 

630 ...................

81.9 80.4 1.5 

800 ...................

73.2 74.1 0.9 

1000 .................

79.2 80.1 0.9 

1250 .................

80.7 82.8 2.1 

1600 .................

81.6 78.6 3.0 

2000 .................

76.2 74.4 1.8 

2500 .................

79.5 80.7 1.2 

3150 .................

80.1 77.1 3.0 

4000 .................

78.9 78.6 0.3 

5000 .................

80.1 77.1 3.0 

6300 .................

80.7 80.4 0.3 

8000 .................

84.3 85.5 1.2 

10000 ...............

81.3 79.8 1.5 

12500 ...............

80.7 80.1 0.6 

16000 ...............

71.1 71.1 0.0 

Average 1.1 

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