Federal Aviation Administration, DOT

Section 25.1013

minutes cruise at a speed for maximum
range. However, if there is an auxiliary
control independent of the main jettisoning control, the system may be designed to jettison the remaining fuel
by means of the auxiliary jettisoning
control.
(g) The fuel jettisoning valve must be
designed to allow flight personnel to
close the valve during any part of the
jettisoning operation.
(h) Unless it is shown that using any
means (including flaps, slots, and slats)
for changing the airflow across or
around the wings does not adversely affect fuel jettisoning, there must be a
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 system will not result in a hazardous condition due to unsymmetrical jettisoning 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]

spaschal on DSK3GDR082PROD with CFR

OIL SYSTEM
Section 25.1011 General.
(a) Each engine must have an independent 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 endurance of the airplane under critical operating conditions and the approved
maximum allowable oil consumption of
the engine under the same conditions,
plus a suitable margin to ensure system circulation. Instead of a rational
analysis of airplane range for the purpose of computing oil requirements for
reciprocating engine powered airplanes, 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 reserve 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 substantiated by data on actual engine oil consumption.
Section 25.1013 Oil tanks.
(a) Installation. Each oil tank installation must meet the requirements of
Section 25.967.
(b) Expansion space. Oil tank expansion space must be provided as follows:
(1) Each oil tank used with a reciprocating engine must have an expansion
space of not less than the greater of 10
percent of the tank capacity or 0.5 gallon, and each oil tank used with a turbine 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 cannot 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 temperature. There must be a shutoff valve at
the outlet of each oil tank used with a
turbine engine, unless the external portion of the oil system (including the oil
tank supports) is fireproof.
(f) Flexible oil tank liners. Each flexible oil tank liner must be approved or

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