324
14 CFR Ch. I (1–1–24 Edition)
§ 25.1011
placard, adjacent to the jettisoning
control, to warn flight crewmembers
against jettisoning fuel while the
means that change the airflow are
being used.
(i) The fuel jettisoning system must
be designed so that any reasonably
probable single malfunction in the sys-
tem will not result in a hazardous con-
dition due to unsymmetrical jetti-
soning of, or inability to jettison, fuel.
[Doc. No. 5066, 29 FR 18291, Dec. 24, 1964, as
amended by Amdt. 25–18, 33 FR 12226, Aug. 30,
1968; Amdt. 25–57, 49 FR 6848, Feb. 23, 1984;
Amdt. 25–108, 67 FR 70827, Nov. 26, 2002]
O
IL
S
YSTEM
§ 25.1011
General.
(a) Each engine must have an inde-
pendent oil system that can supply it
with an appropriate quantity of oil at a
temperature not above that safe for
continuous operation.
(b) The usable oil capacity may not
be less than the product of the endur-
ance of the airplane under critical op-
erating conditions and the approved
maximum allowable oil consumption of
the engine under the same conditions,
plus a suitable margin to ensure sys-
tem circulation. Instead of a rational
analysis of airplane range for the pur-
pose of computing oil requirements for
reciprocating engine powered air-
planes, the following fuel/oil ratios
may be used:
(1) For airplanes without a reserve
oil or oil transfer system, a fuel/oil
ratio of 30:1 by volume.
(2) For airplanes with either a re-
serve oil or oil transfer system, a fuel/
oil ratio of 40:1 by volume.
(c) Fuel/oil ratios higher than those
prescribed in paragraphs (b)(1) and (2)
of this section may be used if substan-
tiated by data on actual engine oil con-
sumption.
§ 25.1013
Oil tanks.
(a)
Installation. Each oil tank instal-
lation must meet the requirements of
§ 25.967.
(b)
Expansion space. Oil tank expan-
sion space must be provided as follows:
(1) Each oil tank used with a recipro-
cating engine must have an expansion
space of not less than the greater of 10
percent of the tank capacity or 0.5 gal-
lon, and each oil tank used with a tur-
bine engine must have an expansion
space of not less than 10 percent of the
tank capacity.
(2) Each reserve oil tank not directly
connected to any engine may have an
expansion space of not less than two
percent of the tank capacity.
(3) It must be impossible to fill the
expansion space inadvertently with the
airplane in the normal ground attitude.
(c)
Filler connection. Each recessed oil
tank filler connection that can retain
any appreciable quantity of oil must
have a drain that discharges clear of
each part of the airplane. In addition,
each oil tank filler cap must provide an
oil-tight seal.
(d)
Vent. Oil tanks must be vented as
follows:
(1) Each oil tank must be vented
from the top part of the expansion
space so that venting is effective under
any normal flight condition.
(2) Oil tank vents must be arranged
so that condensed water vapor that
might freeze and obstruct the line can-
not accumulate at any point.
(e)
Outlet. There must be means to
prevent entrance into the tank itself,
or into the tank outlet, of any object
that might obstruct the flow of oil
through the system. No oil tank outlet
may be enclosed by any screen or guard
that would reduce the flow of oil below
a safe value at any operating tempera-
ture. There must be a shutoff valve at
the outlet of each oil tank used with a
turbine engine, unless the external por-
tion of the oil system (including the oil
tank supports) is fireproof.
(f)
Flexible oil tank liners. Each flexi-
ble oil tank liner must be approved or
must be shown to be suitable for the
particular application.
[Doc. No. 5066, 29 FR 18291, Dec. 24, 1964, as
amended by Amdt. 25–19, 33 FR 15410, Oct. 17,
1968; Amdt. 25–23, 35 FR 5677, Apr. 8, 1970;
Amdt. 25–36, 39 FR 35460, Oct. 1, 1974; Amdt.
25–57, 49 FR 6848, Feb. 23, 1984; Amdt. 25–72, 55
FR 29785, July 20, 1990]
§ 25.1015
Oil tank tests.
Each oil tank must be designed and
installed so that—
(a) It can withstand, without failure,
each vibration, inertia, and fluid load
that it may be subjected to in oper-
ation; and
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