483
Federal Aviation Administration, DOT
§ 25.1043
system with the strainer or filter ele-
ment completely blocked.
[Amdt. 25–36, 39 FR 35461, Oct. 1, 1974, as
amended by Amdt. 25–57, 49 FR 6848, Feb. 23,
1984]
§ 25.1021
Oil system drains.
A drain (or drains) must be provided
to allow safe drainage of the oil sys-
tem. Each drain must—
(a) Be accessible; and
(b) Have manual or automatic means
for positive locking in the closed posi-
tion.
[Amdt. 25–57, 49 FR 6848, Feb. 23, 1984]
§ 25.1023
Oil radiators.
(a) Each oil radiator must be able to
withstand, without failure, any vibra-
tion, inertia, and oil pressure load to
which it would be subjected in oper-
ation.
(b) Each oil radiator air duct must be
located so that, in case of fire, flames
coming from normal openings of the
engine nacelle cannot impinge directly
upon the radiator.
§ 25.1025
Oil valves.
(a) Each oil shutoff must meet the re-
quirements of § 25.1189.
(b) The closing of oil shutoff means
may not prevent propeller feathering.
(c) Each oil valve must have positive
stops or suitable index provisions in
the ‘‘on’’ and ‘‘off’’ positions and must
be supported so that no loads resulting
from its operation or from accelerated
flight conditions are transmitted to
the lines attached to the valve.
§ 25.1027
Propeller feathering system.
(a) If the propeller feathering system
depends on engine oil, there must be
means to trap an amount of oil in the
tank if the supply becomes depleted
due to failure of any part of the lubri-
cating system other than the tank
itself.
(b) The amount of trapped oil must
be enough to accomplish the feathering
operation and must be available only
to the feathering pump.
(c) The ability of the system to ac-
complish feathering with the trapped
oil must be shown. This may be done
on the ground using an auxiliary
source of oil for lubricating the engine
during operation.
(d) Provision must be made to pre-
vent sludge or other foreign matter
from affecting the safe operation of the
propeller feathering system.
[Doc. No. 5066, 29 FR 18291, Dec. 24, 1964, as
amended by Amdt. 25–38, 41 FR 55467, Dec. 20,
1976]
C
OOLING
§ 25.1041
General.
The powerplant and auxiliary power
unit cooling provisions must be able to
maintain the temperatures of power-
plant components, engine fluids, and
auxiliary power unit components and
fluids within the temperature limits
established for these components and
fluids, under ground, water, and flight
operating conditions, and after normal
engine or auxiliary power unit shut-
down, or both.
[Amdt. 25–38, 41 FR 55467, Dec. 20, 1976]
§ 25.1043
Cooling tests.
(a)
General. Compliance with § 25.1041
must be shown by tests, under critical
ground, water, and flight operating
conditions. For these tests, the fol-
lowing apply:
(1) If the tests are conducted under
conditions deviating from the max-
imum ambient atmospheric tempera-
ture, the recorded powerplant tempera-
tures must be corrected under para-
graphs (c) and (d) of this section.
(2) No corrected temperatures deter-
mined under paragraph (a)(1) of this
section may exceed established limits.
(3) For reciprocating engines, the fuel
used during the cooling tests must be
the minimum grade approved for the
engines, and the mixture settings must
be those normally used in the flight
stages for which the cooling tests are
conducted. The test procedures must be
as prescribed in § 25.1045.
(b)
Maximum ambient atmospheric tem-
perature. A maximum ambient atmos-
pheric temperature corresponding to
sea level conditions of at least 100 de-
grees F must be established. The as-
sumed temperature lapse rate is 3.6 de-
grees F per thousand feet of altitude
above sea level until a temperature of
¥69.7 degrees F is reached, above which
altitude the temperature is considered
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