page-57

541

Federal Aviation Administration, DOT

§ 27.1121

from entering the engine intake sys-
tem; 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.

[Doc. No. 5074, 29 FR 15695, Nov. 24, 1964, as
amended by Amdt. 27–2, 33 FR 964, Jan. 26,
1968; Amdt. 27–23, 53 FR 34214, Sept. 2, 1988]

§ 27.1093

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 degrees F., and with the en-
gines at 75 percent of maximum contin-
uous 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 degrees F.;

(2) Each rotorcraft with sea level en-

gines using carburetors tending to pre-
vent icing has a sheltered alternate
source of air, and that the preheat sup-
plied to the alternate air intake is not
less than that provided by the engine
cooling air downstream of the cyl-
inders;

(3) Each rotorcraft with altitude en-

gines using conventional venturi car-
buretors has a preheater capable of
providing a heat rise of 120 degrees 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—

(i) 100 degrees F.; or
(ii) If a fluid deicing system is used,

at least 40 degrees F.

(b)

Turbine engine.

(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 Part 29 of this chapter;
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

(between

and

C) and has a liq-

uid water content not less than 0.3
gram 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 superchargers
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,
for the applicable altitude and oper-
ating condition because of super-
charging.

(Secs. 313(a), 601, and 603, 72 Stat. 752, 775, 49
U.S.C. 1354(a), 1421, and 1423; sec. 6(c), 49
U.S.C. 1655(c))

[Doc. No. 5074, 29 FR 15695, Nov. 24, 1964, as
amended by Amdt. 27–11, 41 FR 55470, Dec. 20,
1976; Amdt. 27–12, 42 FR 15045, Mar. 17, 1977;
Amdt. 27–20, 49 FR 6849, Feb. 23, 1984; Amdt.
27–23, 53 FR 34214, Sept. 2, 1988]

XHAUST

YSTEM

§ 27.1121

General.

For each exhaust system—
(a) There must be means for thermal

expansion of manifolds and pipes;

(b) There must be means to prevent

local hot spots;

clear of the engine air intake, fuel sys-
tem components, and drains;

(d) Each exhaust system part with a

surface hot enough to ignite flammable
fluids or vapors must be located or
shielded so that leakage from any sys-
tem carrying flammable fluids or va-
pors will not result in a fire caused by
impingement of the fluids or vapors on

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