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14 CFR Ch. I (1–1–18 Edition) 

Pt. 135, App. B 

(3) Be installed according to limitations 

specified for that equipment; and 

(4) Function properly when installed. 
(b) Systems and installations must be de-

signed to safeguard against hazards to the 
aircraft in the event of their malfunction or 

(c) Where an installation, the functioning 

of which is necessary in showing compliance 
with the applicable requirements, requires a 
power supply, that installation must be con-
sidered an essential load on the power sup-
ply, and the power sources and the distribu-
tion system must be capable of supplying the 
following power loads in probable operation 
combinations and for probable durations: 

(1) All essential loads after failure of any 

prime mover, power converter, or energy 
storage device. 

(2) All essential loads after failure of any 

one engine on two-engine airplanes. 

(3) In determining the probable operating 

combinations and durations of essential 
loads for the power failure conditions de-
scribed in paragraphs (1) and (2) of this para-
graph, it is permissible to assume that the 
power loads are reduced in accordance with a 
monitoring procedure which is consistent 
with safety in the types of operations au-

60.  Ventilation.  The ventilation system of 

the airplane must meet FAR 23.831, and in 
addition, for pressurized aircraft, the ven-
tilating air in flight crew and passenger com-
partments must be free of harmful or haz-
ardous concentrations of gases and vapors in 
normal operation and in the event of reason-
ably probable failures or malfunctioning of 
the ventilating, heating, pressurization, or 
other systems, and equipment. If accumula-
tion of hazardous quantities of smoke in the 
cockpit area is reasonably probable, smoke 
evacuation must be readily accomplished. 

Electrical Systems and Equipment 

61.  General.  The electrical systems and 

equipment of the airplane must meet FAR 
23.1351, and the following: 

(a)  Electrical system capacity. The required 

generating capacity, and number and kinds 
of power sources must— 

(1) Be determined by an electrical load 

analysis; and 

(2) Meet FAR 23.1301. 

(b)  Generating system. The generating sys-

tem includes electrical power sources, main 
power busses, transmission cables, and asso-
ciated control, regulation and protective de-
vices. It must be designed so that— 

(1) The system voltage and frequency (as 

applicable) at the terminals of all essential 
load equipment can be maintained within 
the limits for which the equipment is de-
signed, during any probable operating condi-

(2) System transients due to switching, 

fault clearing, or other causes do not make 
essential loads inoperative, and do not cause 
a smoke or fire hazard; 

(3) There are means, accessible in flight to 

appropriate crewmembers, for the individual 
and collective disconnection of the electrical 
power sources from the system; and 

(4) There are means to indicate to appro-

priate crewmembers the generating system 
quantities essential for the safe operation of 
the system, including the voltage and cur-
rent supplied by each generator. 

62.  Electrical equipment and installation. 

Electrical equipment, controls, and wiring 
must be installed so that operation of any 
one unit or system of units will not ad-
versely affect the simultaneous operation of 
any other electrical unit or system essential 
to the safe operation. 

63.  Distribution system. (a) For the purpose 

of complying with this section, the distribu-
tion system includes the distribution busses, 
their associated feeders, and each control 
and protective device. 

(b) Each system must be designed so that 

essential load circuits can be supplied in the 
event of reasonably probable faults or open 
circuits, including faults in heavy current 
carrying cables. 

(c) If two independent sources of electrical 

power for particular equipment or systems 
are required under this appendix, their elec-
trical energy supply must be ensured by 
means such as duplicate electrical equip-
ment, throwover switching, or multichannel 
or loop circuits separately routed. 

64.  Circuit protective devices. The circuit 

protective devices for the electrical circuits 
of the airplane must meet FAR 23.1357, and 
in addition circuits for loads which are es-
sential to safe operation must have indi-
vidual and exclusive circuit protection. 















Parameters Range 

Installed system



accuracy (to recovered data) 

Sampling inter-

val (per second) 




read out 

Relative time (from recorded 

on prior to takeoff).

25 hr minimum ...............

±0.125% per hour .................

1 ........................

1 sec. 

Indicated airspeed ..................



to V


(KIAS) .............

±5% or ±10 kts., whichever is 

greater. Resolution 2 kts. 
below 175 KIAS.

1 ........................



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