299 

Federal Aviation Administration, DOT 

§ 23.1308 

(1) For each engine, an indicator to 

indicate thrust or to indicate a param-
eter that can be related to thrust, in-
cluding a free air temperature indi-
cator if needed for this purpose. 

(2) For each engine, a position indi-

cating means to indicate to the flight 
crew when the thrust reverser, if in-
stalled, is in the reverse thrust posi-
tion. 

(e) 

For turbopropeller-powered air-

planes.  In addition to the powerplant 
instruments required by paragraphs (a) 
and (c) of this section, the following 
powerplant instruments are required: 

(1) A torque indicator for each en-

gine. 

(2) A position indicating means to in-

dicate to the flight crew when the pro-
peller blade angle is below the flight 
low pitch position, for each propeller, 
unless it can be shown that such occur-
rence is highly improbable. 

[Doc. No. 26344, 58 FR 18975, Apr. 9, 1993; 58 
FR 27060, May 6, 1993; Amdt. 23–51, 61 FR 5138, 
Feb. 9, 1996; Amdt. 23–52, 61 FR 13644, Mar. 27, 
1996] 

§ 23.1306

Electrical and electronic sys-

tem lightning protection. 

(a) Each electrical and electronic 

system that performs a function, for 
which failure would prevent the contin-
ued safe flight and landing of the air-
plane, must be designed and installed 
so that— 

(1) The function is not adversely af-

fected during and after the time the 
airplane is exposed to lightning; and 

(2) The system automatically recov-

ers normal operation of that function 
in a timely manner after the airplane 
is exposed to lightning. 

(b) For airplanes approved for instru-

ment flight rules operation, each elec-
trical and electronic system that per-
forms a function, for which failure 
would reduce the capability of the air-
plane or the ability of the flightcrew to 
respond to an adverse operating condi-
tion, must be designed and installed so 
that the function recovers normal op-
eration in a timely manner after the 
airplane is exposed to lightning. 

[Doc. No. FAA–2010–0224; 76 FR 33135, June 8, 
2011] 

§ 23.1307

Miscellaneous equipment. 

The equipment necessary for an air-

plane to operate at the maximum oper-
ating altitude and in the kinds of oper-
ation and meteorological conditions 
for which certification is requested and 
is approved in accordance with § 23.1559 
must be included in the type design. 

[Doc. No. 4080, 29 FR 17955, Dec. 18, 1964; 30 
FR 258, Jan. 9, 1965, as amended by Amdt. 23– 
23, 43 FR 50593, Oct. 30, 1978; Amdt. 23–43, 58 
FR 18976, Apr. 9, 1993; Amdt. 23–49, 61 FR 5168, 
Feb. 9, 1996] 

§ 23.1308

High-intensity Radiated 

Fields (HIRF) Protection. 

(a) Except as provided in paragraph 

(d) of this section, each electrical and 
electronic system that performs a func-
tion whose failure would prevent the 
continued safe flight and landing of the 
airplane must be designed and installed 
so that— 

(1) The function is not adversely af-

fected during and after the time the 
airplane is exposed to HIRF environ-
ment I, as described in appendix J to 
this part; 

(2) The system automatically recov-

ers normal operation of that function, 
in a timely manner, after the airplane 
is exposed to HIRF environment I, as 
described in appendix J to this part, 
unless the system’s recovery conflicts 
with other operational or functional 
requirements of the system; and 

(3) The system is not adversely af-

fected during and after the time the 
airplane is exposed to HIRF environ-
ment II, as described in appendix J to 
this part. 

(b) Each electrical and electronic 

system that performs a function whose 
failure would significantly reduce the 
capability of the airplane or the ability 
of the flightcrew to respond to an ad-
verse operating condition must be de-
signed and installed so the system is 
not adversely affected when the equip-
ment providing the function is exposed 
to equipment HIRF test level 1 or 2, as 
described in appendix J to this part. 

(c) Each electrical and electronic sys-

tem that performs a function whose 
failure would reduce the capability of 
the airplane or the ability of the 
flightcrew to respond to an adverse op-
erating condition must be designed and 
installed so the system is not adversely 

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