191 

Federal Aviation Administration, DOT 

§ 23.2515 

within or through each designated fire 
zone. This means must— 

(1) Not restrict flow or limit oper-

ation of any remaining powerplant or 
auxiliary power unit, or equipment 
necessary for safety; 

(2) Prevent inadvertent operation; 

and 

(3) Be located outside the fire zone 

unless an equal degree of safety is pro-
vided with a means inside the fire zone. 

(e) A means to ensure the prompt de-

tection of fire must be provided for 
each designated fire zone— 

(1) On a multiengine airplane where 

detection will mitigate likely hazards 
to the airplane; or 

(2) That contains a fire extinguisher. 
(f) A means to extinguish fire within 

a fire zone, except a combustion heater 
fire zone, must be provided for— 

(1) Any fire zone located outside the 

pilot’s view; 

(2) Any fire zone embedded within the 

fuselage, which must also include a re-
dundant means to extinguish fire; and 

(3) Any fire zone on a level 4 airplane. 

Subpart F—Equipment 

§ 23.2500

Airplane level systems re-

quirements. 

This section applies generally to in-

stalled equipment and systems unless a 
section of this part imposes require-
ments for a specific piece of equipment, 
system, or systems. 

(a) The equipment and systems re-

quired for an airplane to operate safely 
in the kinds of operations for which 
certification is requested (Day VFR, 
Night VFR, IFR) must be designed and 
installed to— 

(1) Meet the level of safety applicable 

to the certification and performance 
level of the airplane; and 

(2) Perform their intended function 

throughout the operating and environ-
mental limits for which the airplane is 
certificated. 

(b) The systems and equipment not 

covered by paragraph (a), considered 
separately and in relation to other sys-
tems, must be designed and installed so 
their operation does not have an ad-
verse effect on the airplane or its occu-
pants. 

§ 23.2505

Function and installation. 

When installed, each item of equip-

ment must function as intended. 

§ 23.2510

Equipment, systems, and in-

stallations. 

For any airplane system or equip-

ment whose failure or abnormal oper-
ation has not been specifically ad-
dressed by another requirement in this 
part, the applicant must design and in-
stall each system and equipment, such 
that there is a logical and acceptable 
inverse relationship between the aver-
age probability and the severity of fail-
ure conditions to the extent that: 

(a) Each catastrophic failure condi-

tion is extremely improbable; 

(b) Each hazardous failure condition 

is extremely remote; and 

(c) Each major failure condition is 

remote. 

§ 23.2515

Electrical and electronic sys-

tem lightning protection. 

An airplane approved for IFR oper-

ations must meet the following re-
quirements, unless an applicant shows 
that exposure to lightning is unlikely: 

(a) Each electrical or electronic sys-

tem that performs a function, the fail-
ure of which would prevent the contin-
ued safe flight and landing of the air-
plane, must be designed and installed 
such that— 

(1) The function at the airplane level 

is not adversely affected during and 
after the time the airplane is exposed 
to lightning; and 

(2) The system recovers normal oper-

ation of that function in a timely man-
ner after the airplane is exposed to 
lightning unless the system’s recovery 
conflicts with other operational or 
functional requirements of the system. 

(b) Each electrical and electronic 

system that performs a function, the 
failure of which would significantly re-
duce the capability of the airplane or 
the ability of the flightcrew to respond 
to an adverse operating condition, 
must be designed and installed such 
that the system recovers normal oper-
ation of that function in a timely man-
ner after the airplane is exposed to 
lightning. 

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