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542 

14 CFR Ch. I (1–1–24 Edition) 

§ 27.1093 

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 

¥

9

° 

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] 

E

XHAUST

S

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; 

(c) Exhaust gases must discharge 

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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543 

Federal Aviation Administration, DOT 

§ 27.1143 

any part of the exhaust system includ-
ing shields for the exhaust system; 

(e) Exhaust gases may not impair 

pilot vision at night due to glare; 

(f) If significant traps exist, each tur-

bine engine exhaust system must have 
drains discharging clear of the rotor-
craft, in any normal ground and flight 
attitudes, to prevent fuel accumulation 
after the failure of an attempted en-
gine start; 

(g) Each exhaust heat exchanger 

must incorporate means to prevent 
blockage of the exhaust port after any 
internal heat exchanger failure. 

(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. 27–12, 42 FR 15045, Mar. 17, 
1977] 

§ 27.1123

Exhaust piping. 

(a) Exhaust piping must be heat and 

corrosion resistant, and must have pro-
visions to prevent failure due to expan-
sion by operating temperatures. 

(b) Exhaust piping must be supported 

to withstand any vibration and inertia 
loads to which it would be subjected in 
operations. 

(c) Exhaust piping connected to com-

ponents between which relative motion 
could exist must have provisions for 
flexibility. 

[Amdt. 27–11, 41 FR 55470, Dec. 20, 1976] 

P

OWERPLANT

C

ONTROLS AND

 

A

CCESSORIES

 

§ 27.1141

Powerplant controls: general. 

(a) Powerplant controls must be lo-

cated and arranged under § 27.777 and 
marked under § 27.1555. 

(b) Each flexible powerplant control 

must be approved. 

(c) Each control must be able to 

maintain any set position without— 

(1) Constant attention; or 
(2) Tendency to creep due to control 

loads or vibration. 

(d) Controls of powerplant valves re-

quired for safety must have— 

(1) For manual valves, positive stops 

or in the case of fuel valves suitable 
index provisions, in the open and closed 
position; and 

(2) For power-assisted valves, a 

means to indicate to the flight crew 
when the valve— 

(i) Is in the fully open or fully closed 

position; or 

(ii) Is moving between the fully open 

and fully closed position. 

(e) For turbine engine powered rotor-

craft, no single failure or malfunction, 
or probable combination thereof, in 
any powerplant control system may 
cause the failure of any powerplant 
function necessary for safety. 

(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. 27–12, 42 FR 15045, Mar. 17, 
1977; Amdt. 27–23, 53 FR 34214, Sept. 2, 1988; 
Amdt. 27–33, 61 FR 21907, May 10, 1996] 

§ 27.1143

Engine controls. 

(a) There must be a separate power 

control for each engine. 

(b) Power controls must be grouped 

and arranged to allow— 

(1) Separate control of each engine; 

and 

(2) Simultaneous control of all en-

gines. 

(c) Each power control must provide 

a positive and immediately responsive 
means of controlling its engine. 

(d) If a power control incorporates a 

fuel shutoff feature, the control must 
have a means to prevent the inad-
vertent movement of the control into 
the shutoff position. The means must— 

(1) Have a positive lock or stop at the 

idle position; and 

(2) Require a separate and distinct 

operation to place the control in the 
shutoff position. 

(e) For rotorcraft to be certificated 

for a 30-second OEI power rating, a 
means must be provided to automati-
cally activate and control the 30-sec-
ond OEI power and prevent any engine 
from exceeding the installed engine 
limits associated with the 30-second 
OEI power rating approved for the 
rotorcraft. 

[Doc. No. 5074, 29 FR 15695, Nov. 24, 1964, as 
amended by Amdt. 27–11, 41 FR 55470, Dec. 20, 
1976; Amdt. 27–23, 53 FR 34214, Sept. 2, 1988; 
Amdt. 27–29, 59 FR 47767, Sept. 16, 1994] 

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