title-14-part-25-sec25-1125

330

14 CFR Ch. I (1–1–24 Edition)

§ 25.1107

(d) It must be impossible for fuel to

strike any screen.

§ 25.1107

Inter-coolers and after-cool-

ers.

Each inter-cooler and after-cooler

must be able to withstand any vibra-
tion, inertia, and air pressure load to
which it would be subjected in oper-
ation.

XHAUST

YSTEM

§ 25.1121

General.

For powerplant and auxiliary power

unit installations the following apply:

(a) Each exhaust system must ensure

safe disposal of exhaust gases without
fire hazard or carbon monoxide con-
tamination in any personnel compart-
ment. For test purposes, any accept-
able carbon monoxide detection meth-
od may be used to show the absence of
carbon monoxide.

(b) 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
any part of the exhaust system includ-
ing shields for the exhaust system.

gases could strike, or that could be
subjected to high temperatures from
exhaust system parts, must be fire-
proof. All exhaust system components
must be separated by fireproof shields
from adjacent parts of the airplane
that are outside the engine and auxil-
iary power unit compartments.

(d) No exhaust gases may discharge

so as to cause a fire hazard with re-
spect to any flammable fluid vent or
drain.

(e) No exhaust gases may discharge

where they will cause a glare seriously
affecting pilot vision at night.

(f) Each exhaust system component

must be ventilated to prevent points of
excessively high temperature.

(g) Each exhaust shroud must be ven-

tilated or insulated to avoid, during
normal operation, a temperature high

enough to ignite any flammable fluids
or vapors external to the shroud.

[Doc. No. 5066, 29 FR 18291, Dec. 24, 1964, as
amended by Amdt. 25–40, 42 FR 15043, Mar. 17,
1977]

§ 25.1123

Exhaust piping.

For powerplant and auxiliary power

unit installations, the following apply:

(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) Piping must be supported to with-

stand any vibration and inertia loads
to which it would be subjected in oper-
ation; and

between which relative motion could
exist must have means for flexibility.

[Doc. No. 5066, 29 FR 18291, Dec. 24, 1964, as
amended by Amdt. 25–40, 42 FR 15044, Mar. 17,
1977]

§ 25.1125

Exhaust heat exchangers.

For reciprocating engine powered

airplanes, the following apply:

(a) Each exhaust heat exchanger

must be constructed and installed to
withstand each vibration, inertia, and
other load to which it would be sub-
jected in operation. In addition—

(1) Each exchanger must be suitable

for continued operation at high tem-
peratures and resistant to corrosion
from exhaust gases;

(2) There must be means for the in-

spection of the critical parts of each
exchanger;

(3) Each exchanger must have cooling

provisions wherever it is subject to
contact with exhaust gases; and

(4) No exhaust heat exchanger or

muff may have any stagnant areas or
liquid traps that would increase the
probability of ignition of flammable
fluids or vapors that might be present
in case of the failure or malfunction of
components carrying flammable fluids.

(b) If an exhaust heat exchanger is

used for heating ventilating air—

(1) There must be a secondary heat

exchanger between the primary ex-
haust gas heat exchanger and the ven-
tilating air system; or

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§ 25.1143

(2) Other means must be used to pre-

clude the harmful contamination of the
ventilating air.

[Doc. No. 5066, 29 FR 18291, Dec. 24, 1964, as
amended by Amdt. 25–38, 41 FR 55467, Dec. 20,
1976]

§ 25.1127

Exhaust driven turbo-super-

chargers.

(a) Each exhaust driven turbo-super-

charger must be approved or shown to
be suitable for the particular applica-
tion. It must be installed and sup-
ported to ensure safe operation be-
tween normal inspections and over-
hauls. In addition, there must be provi-
sions for expansion and flexibility be-
tween exhaust conduits and the tur-
bine.

(b) There must be provisions for lu-

bricating the turbine and for cooling
turbine parts where temperatures are
critical.

control system malfunctions, the tur-
bine speed may not exceed its max-
imum allowable value. Except for the
waste gate operating components, the
components provided for meeting this
requirement must be independent of
the normal turbo-supercharger con-
trols.

OWERPLANT

ONTROLS AND

CCESSORIES

§ 25.1141

Powerplant controls: general.

Each powerplant control must be lo-

cated, arranged, and designed under
§§ 25.777 through 25.781 and marked
under § 25.1555. In addition, it must
meet the following requirements:

(a) Each control must be located so

that it cannot be inadvertently oper-
ated by persons entering, leaving, or
moving normally in, the cockpit.

(b) Each flexible control must be ap-

proved or must be shown to be suitable
for the particular application.

strength and rigidity to withstand op-
erating loads without failure and with-
out excessive deflection.

(d) Each control must be able to

maintain any set position without con-
stant attention by flight crewmembers
and without creep due to control loads
or vibration.

(e) The portion of each powerplant

control located in a designated fire
zone that is required to be operated in
the event of fire must be at least fire
resistant.

(f) For powerplant valve controls lo-

cated in the flight deck there must be
a means:

(1) For the flightcrew to select each

intended position or function of the
valve; and

(2) To indicate to the flightcrew:
(i) The selected position or function

of the valve; and

(ii) When the valve has not responded

as intended to the selected position or
function.

[Doc. No. 5066, 29 FR 18291, Dec. 24, 1964, as
amended by Amdt. 25–40, 42 FR 15044, Mar. 17,
1977; Amdt. 25–72, 55 FR 29785, July 20, 1990;
Amdt. 25–115, 69 FR 40527, July 2, 2004]

§ 25.1142

Auxiliary power unit con-

trols.

Means must be provided on the flight

deck for starting, stopping, and emer-
gency shutdown of each installed auxil-
iary power unit.

[Amdt. 25–46, 43 FR 50598, Oct. 30, 1978]

§ 25.1143

Engine controls.

(a) There must be a separate power or

thrust control for each engine.

(b) Power and thrust controls must

be arranged to allow—

(1) Separate control of each engine;

and

(2) Simultaneous control of all en-

gines.

must provide a positive and imme-
diately responsive means of controlling
its engine.

(d) For each fluid injection (other

than fuel) system and its controls not
provided and approved as part of the
engine, the applicant must show that
the flow of the injection fluid is ade-
quately controlled.

(e) If a power or thrust control incor-

porates a fuel shutoff feature, the con-
trol must have a means to prevent the
inadvertent movement of the control
into the shutoff position. The means
must—

(1) Have a positive lock or stop at the

idle position; and