Section 29.1093

14 CFR Ch. I (1-1-19 Edition)

and auxiliary power unit under the operating conditions for which certification is requested.
(b) Each engine and auxiliary power
unit air induction system must provide
air for proper fuel metering and mixture 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 compartment 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 rotorcraft and rotorcraft incorporating auxiliary 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 located 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]

spaschal on DSK3GDR082PROD with CFR

Section 29.1093 Induction system icing protection.
(a) Reciprocating engines. Each reciprocating engine air induction system
must have means to prevent and eliminate icing. Unless this is done by other
means, it must be shown that, in air
free of visible moisture at a temperature of 30 SectionF., and with the engines at
60 percent of maximum continuous
power - 
(1) Each rotorcraft with sea level engines using conventional venturi carburetors has a preheater that can provide a heat rise of 90 SectionF.;
(2) Each rotorcraft with sea level engines using carburetors tending to prevent icing has a preheater that can
provide a heat rise of 70 SectionF.;

(3) Each rotorcraft with altitude engines using conventional venturi carburetors has a preheater that can provide a heat rise of 120 SectionF.; and
(4) Each rotorcraft with altitude engines using carburetors tending to prevent icing has a preheater that can
provide a heat rise of 100 SectionF.
(b) Turbine engines. (1) It must be
shown that each turbine engine and its
air inlet system can operate throughout the flight power range of the engine (including idling) - 
(i) Without accumulating ice on engine or inlet system components that
would adversely affect engine operation 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 operation, within the limitations established for the rotorcraft.
(2) Each turbine engine must idle for
30 minutes on the ground, with the air
bleed available for engine icing protection at its critical condition, without
adverse effect, in an atmosphere that is
at a temperature between 15Section and 30 SectionF
(between Section9Section and Section1 SectionC) and has a liquid 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
section if the heat rise utilized is that
which will be available, automatically,

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