Code of Federal Regulations - Title 14

487

Federal Aviation Administration, DOT

§ 25.1127

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

(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.

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