645 

Federal Aviation Administration, DOT 

§ 29.1093 

(b) With maximum continuous power, 

maximum weight, and at the altitude 
resulting in zero rate of climb for this 
configuration, until at least five min-
utes after the occurrence of the highest 
temperature recorded. 

I

NDUCTION

S

YSTEM

 

§ 29.1091

Air induction. 

(a) The air induction system for each 

engine and auxiliary power unit must 
supply the air required by that engine 
and auxiliary power unit under the op-
erating conditions for which certifi-
cation is requested. 

(b) Each engine and auxiliary power 

unit air induction system must provide 
air for proper fuel metering and mix-
ture distribution with the induction 
system valves in any position. 

(c) No air intake may open within 

the engine accessory section or within 
other areas of any powerplant compart-
ment where emergence of backfire 
flame would constitute a fire hazard. 

(d) Each reciprocating engine must 

have an alternate air source. 

(e) Each alternate air intake must be 

located to prevent the entrance of rain, 
ice, or other foreign matter. 

(f) For turbine engine powered rotor-

craft and rotorcraft incorporating aux-
iliary power units— 

(1) There must be means to prevent 

hazardous quantities of fuel leakage or 
overflow from drains, vents, or other 
components of flammable fluid systems 
from entering the engine or auxiliary 
power unit intake system; and 

(2) The air inlet ducts must be lo-

cated or protected so as to minimize 
the ingestion of foreign matter during 
takeoff, landing, and taxiing. 

(Secs. 313(a), 601, 603, 604, Federal Aviation 
Act of 1958 (49 U.S.C. 1354(a), 1421, 1423, 1424), 
sec. 6(c), Dept. of Transportation Act (49 
U.S.C. 1655(c))) 

[Doc. No. 5084, 29 FR 16150, Dec. 3, 1964, as 
amended by Amdt. 29–3, 33 FR 969, Jan. 26, 
1968; Amdt. 29–17, 43 FR 50601, Oct. 30, 1978] 

§ 29.1093

Induction system icing pro-

tection. 

(a) 

Reciprocating engines. Each recip-

rocating engine air induction system 
must have means to prevent and elimi-
nate icing. Unless this is done by other 
means, it must be shown that, in air 

free of visible moisture at a tempera-
ture of 30 

°

F., and with the engines at 

60 percent of maximum continuous 
power— 

(1) Each rotorcraft with sea level en-

gines using conventional venturi car-
buretors has a preheater that can pro-
vide a heat rise of 90 

°

F.; 

(2) Each rotorcraft with sea level en-

gines using carburetors tending to pre-
vent icing has a preheater that can 
provide a heat rise of 70 

°

F.; 

(3) Each rotorcraft with altitude en-

gines using conventional venturi car-
buretors has a preheater that can pro-
vide a heat rise of 120 

°

F.; and 

(4) Each rotorcraft with altitude en-

gines using carburetors tending to pre-
vent icing has a preheater that can 
provide a heat rise of 100 

°

F. 

(b) 

Turbine engines. (1) It must be 

shown that each turbine engine and its 
air inlet system can operate through-
out the flight power range of the en-
gine (including idling)— 

(i) Without accumulating ice on en-

gine or inlet system components that 
would adversely affect engine oper-
ation or cause a serious loss of power 
under the icing conditions specified in 
appendix C of this Part; and 

(ii) In snow, both falling and blowing, 

without adverse effect on engine oper-
ation, within the limitations estab-
lished for the rotorcraft. 

(2) Each turbine engine must idle for 

30 minutes on the ground, with the air 
bleed available for engine icing protec-
tion at its critical condition, without 
adverse effect, in an atmosphere that is 
at a temperature between 15

° 

and 30 

°

F 

(between 

¥

9

° 

and 

¥

1 

°

C) and has a liq-

uid water content not less than 0.3 
grams per cubic meter in the form of 
drops having a mean effective diameter 
not less than 20 microns, followed by 
momentary operation at takeoff power 
or thrust. During the 30 minutes of idle 
operation, the engine may be run up 
periodically to a moderate power or 
thrust setting in a manner acceptable 
to the Administrator. 

(c) 

Supercharged reciprocating engines. 

For each engine having a supercharger 
to pressurize the air before it enters 
the carburetor, the heat rise in the air 
caused by that supercharging at any 
altitude may be utilized in determining 
compliance with paragraph (a) of this 

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