314 

14 CFR Ch. I (1–1–14 Edition) 

§ 23.1431 

(b) Except as provided by paragraph 

(c) of this section, in addition to the 
analysis and physical evaluation pre-
scribed in paragraph (a) of this section, 
the effectiveness of the ice protection 
system and its components must be 
shown by flight tests of the airplane or 
its components in measured natural at-
mospheric icing conditions and by one 
or more of the following tests, as found 
necessary to determine the adequacy of 
the ice protection system— 

(1) Laboratory dry air or simulated 

icing tests, or a combination of both, of 
the components or models of the com-
ponents. 

(2) Flight dry air tests of the ice pro-

tection system as a whole, or its indi-
vidual components. 

(3) Flight test of the airplane or its 

components in measured simulated 
icing conditions. 

(c) If certification with ice protection 

has been accomplished on prior type 
certificated airplanes whose designs in-
clude components that are 
thermodynamically and aero-
dynamically equivalent to those used 
on a new airplane design, certification 
of these equivalent components may be 
accomplished by reference to pre-
viously accomplished tests, required in 
§ 23.1419 (a) and (b), provided that the 
applicant accounts for any differences 
in installation of these components. 

(d) A means must be identified or 

provided for determining the formation 
of ice on the critical parts of the air-
plane. Adequate lighting must be pro-
vided for the use of this means during 
night operation. Also, when monitoring 
of the external surfaces of the airplane 
by the flight crew is required for oper-
ation of the ice protection equipment, 
external lighting must be provided that 
is adequate to enable the monitoring to 
be done at night. Any illumination 
that is used must be of a type that will 
not cause glare or reflection that 
would handicap crewmembers in the 
performance of their duties. The Air-
plane Flight Manual or other approved 
manual material must describe the 
means of determining ice formation 
and must contain information for the 
safe operation of the airplane in icing 
conditions. 

[Doc. No. 26344, 58 FR 18977, Apr. 9, 1993] 

M

ISCELLANEOUS

E

QUIPMENT

 

§ 23.1431

Electronic equipment. 

(a) In showing compliance with 

§ 23.1309(a), (b), and (c) with respect to 
radio and electronic equipment and 
their installations, critical environ-
mental conditions must be considered. 

(b) Radio and electronic equipment, 

controls, and wiring must be installed 
so that operation of any unit or system 
of units will not adversely affect the si-
multaneous operation of any other 
radio or electronic unit, or system of 
units, required by this chapter. 

(c) For those airplanes required to 

have more than one flightcrew mem-
ber, or whose operation will require 
more than one flightcrew member, the 
cockpit must be evaluated to deter-
mine if the flightcrew members, when 
seated at their duty station, can con-
verse without difficulty under the ac-
tual cockpit noise conditions when the 
airplane is being operated. If the air-
plane design includes provision for the 
use of communication headsets, the 
evaluation must also consider condi-
tions where headsets are being used. If 
the evaluation shows conditions under 
which it will be difficult to converse, 
an intercommunication system must 
be provided. 

(d) If installed communication equip-

ment includes transmitter ‘‘off-on’’ 
switching, that switching means must 
be designed to return from the ‘‘trans-
mit’’ to the ‘‘off’’ position when it is 
released and ensure that the trans-
mitter will return to the off (non trans-
mitting) state. 

(e) If provisions for the use of com-

munication headsets are provided, it 
must be demonstrated that the 
flightcrew members will receive all 
aural warnings under the actual cock-
pit noise conditions when the airplane 
is being operated when any headset is 
being used. 

[Doc. No. 26344, 58 FR 18977, Apr. 9, 1993, as 
amended by Amdt. 23–49, 61 FR 5169, Feb. 9, 
1996; Amdt. 23–62, 76 FR 75761, Dec. 2, 2011] 

§ 23.1435

Hydraulic systems. 

(a) 

Design.  Each hydraulic system 

must be designed as follows: 

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