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188 

14 CFR Ch. I (1–1–24 Edition) 

§ 23.2335 

(b) Engines in a designated fire zone 

must remain attached to the airplane 
in the event of a fire. 

(c) In designated fire zones, termi-

nals, equipment, and electrical cables 
used during emergency procedures 
must be fire-resistant. 

§ 23.2335

Lightning protection. 

The airplane must be protected 

against catastrophic effects from light-
ning. 

Subpart E—Powerplant 

§ 23.2400

Powerplant installation. 

(a) For the purpose of this subpart, 

the airplane powerplant installation 
must include each component nec-
essary for propulsion, which affects 
propulsion safety, or provides auxiliary 
power to the airplane. 

(b) Each airplane engine and pro-

peller must be type certificated, except 
for engines and propellers installed on 
level 1 low-speed airplanes, which may 
be approved under the airplane type 
certificate in accordance with a stand-
ard accepted by the Administrator that 
contains airworthiness criteria the Ad-
ministrator has found appropriate and 
applicable to the specific design and in-
tended use of the engine or propeller 
and provides a level of safety accept-
able to the Administrator. 

(c) The applicant must construct and 

arrange each powerplant installation 
to account for— 

(1) Likely operating conditions, in-

cluding foreign object threats; 

(2) Sufficient clearance of moving 

parts to other airplane parts and their 
surroundings; 

(3) Likely hazards in operation in-

cluding hazards to ground personnel; 
and 

(4) Vibration and fatigue. 
(d) Hazardous accumulations of 

fluids, vapors, or gases must be iso-
lated from the airplane and personnel 
compartments, and be safely contained 
or discharged. 

(e) Powerplant components must 

comply with their component limita-

tions and installation instructions or 
be shown not to create a hazard. 

[Doc. No. FAA–2015–1621, Amdt. 23–64, 81 FR 
96689, Dec. 30, 2016, as amended by Doc. No. 
FAA–2022–1355, Amdt. 23–65, 87 FR 75710, Dec. 
9, 2022] 

§ 23.2405

Automatic power or thrust 

control systems. 

(a) An automatic power or thrust 

control system intended for in-flight 
use must be designed so no unsafe con-
dition will result during normal oper-
ation of the system. 

(b) Any single failure or likely com-

bination of failures of an automatic 
power or thrust control system must 
not prevent continued safe flight and 
landing of the airplane. 

(c) Inadvertent operation of an auto-

matic power or thrust control system 
by the flightcrew must be prevented, or 
if not prevented, must not result in an 
unsafe condition. 

(d) Unless the failure of an automatic 

power or thrust control system is ex-
tremely remote, the system must— 

(1) Provide a means for the flightcrew 

to verify the system is in an operating 
condition; 

(2) Provide a means for the flightcrew 

to override the automatic function; 
and 

(3) Prevent inadvertent deactivation 

of the system. 

§ 23.2410

Powerplant installation haz-

ard assessment. 

The applicant must assess each pow-

erplant separately and in relation to 
other airplane systems and installa-
tions to show that any hazard resulting 
from the likely failure of any power-
plant system, component, or accessory 
will not— 

(a) Prevent continued safe flight and 

landing or, if continued safe flight and 
landing cannot be ensured, the hazard 
has been minimized; 

(b) Cause serious injury that may be 

avoided; and 

(c) Require immediate action by any 

crewmember for continued operation of 
any remaining powerplant system. 

§ 23.2415

Powerplant ice protection. 

(a) The airplane design, including the 

induction and inlet system, must pre-
vent foreseeable accumulation of ice or 

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189 

Federal Aviation Administration, DOT 

§ 23.2435 

snow that adversely affects powerplant 
operation. 

(b) The powerplant installation de-

sign must prevent any accumulation of 
ice or snow that adversely affects pow-
erplant operation, in those icing condi-
tions for which certification is re-
quested. 

§ 23.2420

Reversing systems. 

Each reversing system must be de-

signed so that— 

(a) No unsafe condition will result 

during normal operation of the system; 
and 

(b) The airplane is capable of contin-

ued safe flight and landing after any 
single failure, likely combination of 
failures, or malfunction of the revers-
ing system. 

§ 23.2425

Powerplant operational char-

acteristics. 

(a) The installed powerplant must op-

erate without any hazardous character-
istics during normal and emergency op-
eration within the range of operating 
limitations for the airplane and the en-
gine. 

(b) The pilot must have the capa-

bility to stop the powerplant in flight 
and restart the powerplant within an 
established operational envelope. 

§ 23.2430

Fuel systems. 

(a) Each fuel system must— 
(1) Be designed and arranged to pro-

vide independence between multiple 
fuel storage and supply systems so that 
failure of any one component in one 
system will not result in loss of fuel 
storage or supply of another system; 

(2) Be designed and arranged to pre-

vent ignition of the fuel within the sys-
tem by direct lightning strikes or 
swept lightning strokes to areas where 
such occurrences are highly probable, 
or by corona or streamering at fuel 
vent outlets; 

(3) Provide the fuel necessary to en-

sure each powerplant and auxiliary 
power unit functions properly in all 
likely operating conditions; 

(4) Provide the flightcrew with a 

means to determine the total useable 
fuel available and provide uninter-
rupted supply of that fuel when the 
system is correctly operated, account-
ing for likely fuel fluctuations; 

(5) Provide a means to safely remove 

or isolate the fuel stored in the system 
from the airplane; 

(6) Be designed to retain fuel under 

all likely operating conditions and 
minimize hazards to the occupants dur-
ing any survivable emergency landing. 
For level 4 airplanes, failure due to 
overload of the landing system must be 
taken into account; and 

(7) Prevent hazardous contamination 

of the fuel supplied to each powerplant 
and auxiliary power unit. 

(b) Each fuel storage system must— 
(1) Withstand the loads under likely 

operating conditions without failure; 

(2) Be isolated from personnel com-

partments and protected from hazards 
due to unintended temperature influ-
ences; 

(3) Be designed to prevent significant 

loss of stored fuel from any vent sys-
tem due to fuel transfer between fuel 
storage or supply systems, or under 
likely operating conditions; 

(4) Provide fuel for at least one-half 

hour of operation at maximum contin-
uous power or thrust; and 

(5) Be capable of jettisoning fuel safe-

ly if required for landing. 

(c) Each fuel storage refilling or re-

charging system must be designed to— 

(1) Prevent improper refilling or re-

charging; 

(2) Prevent contamination of the fuel 

stored during likely operating condi-
tions; and 

(3) Prevent the occurrence of any 

hazard to the airplane or to persons 
during refilling or recharging. 

§ 23.2435

Powerplant induction and 

exhaust systems. 

(a) The air induction system for each 

powerplant or auxiliary power unit and 
their accessories must— 

(1) Supply the air required by that 

powerplant or auxiliary power unit and 
its accessories under likely operating 
conditions; 

(2) Be designed to prevent likely haz-

ards in the event of fire or backfire; 

(3) Minimize the ingestion of foreign 

matter; and 

(4) Provide an alternate intake if 

blockage of the primary intake is like-
ly. 

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