538
14 CFR Ch. I (1–1–24 Edition)
§ 27.995
which relative motion could exist must
have provisions for flexibility.
(c) Flexible hose must be approved.
(d) Each flexible connection in fuel
lines that may be under pressure or
subjected to axial loading must use
flexible hose assemblies.
(e) No flexible hose that might be ad-
versely affected by high temperatures
may be used where excessive tempera-
tures will exist during operation or
after engine shutdown.
[Doc. No. 5074, 29 FR 15695, Nov. 24, 1964, as
amended by Amdt. 27–2, 33 FR 964, Jan. 26,
1968]
§ 27.995
Fuel valves.
(a) There must be a positive, quick-
acting valve to shut off fuel to each en-
gine individually.
(b) The control for this valve must be
within easy reach of appropriate crew-
members.
(c) Where there is more than one
source of fuel supply there must be
means for independent feeding from
each source.
(d) No shutoff valve may be on the
engine side of any firewall.
§ 27.997
Fuel strainer or filter.
There must be a fuel strainer or filter
between the fuel tank outlet and the
inlet of the first fuel system compo-
nent which is susceptible to fuel con-
tamination, including but not limited
to the fuel metering device or an en-
gine positive displacement pump,
whichever is nearer the fuel tank out-
let. This fuel strainer or filter must—
(a) Be accessible for draining and
cleaning and must incorporate a screen
or element which is easily removable;
(b) Have a sediment trap and drain
except that it need not have a drain if
the strainer or filter is easily remov-
able for drain purposes;
(c) Be mounted so that its weight is
not supported by the connecting lines
or by the inlet or outlet connections of
the strainer or filter itself, unless ade-
quate strength margins under all load-
ing conditions are provided in the lines
and connections; and
(d) Provide a means to remove from
the fuel any contaminant which would
jeopardize the flow of fuel through
rotorcraft or engine fuel system com-
ponents required for proper rotorcraft
fuel system or engine fuel system oper-
ation.
[Amdt. 27–9, 39 FR 35461, Oct. 1, 1974, as
amended by Amdt. 27–20, 49 FR 6849, Feb. 23,
1984; Amdt. 27–23, 53 FR 34213, Sept. 2, 1988]
§ 27.999
Fuel system drains.
(a) There must be at least one acces-
sible drain at the lowest point in each
fuel system to completely drain the
system with the rotorcraft in any
ground attitude to be expected in serv-
ice.
(b) Each drain required by paragraph
(a) of this section must—
(1) Discharge clear of all parts of the
rotorcraft;
(2) Have manual or automatic means
to assure positive closure in the off po-
sition; and
(3) Have a drain valve—
(i) That is readily accessible and
which can be easily opened and closed;
and
(ii) That is either located or pro-
tected to prevent fuel spillage in the
event of a landing with landing gear re-
tracted.
[Doc. No. 574, 29 FR 15695, Nov. 24, 1964, as
amended by Amdt. 27–11, 41 FR 55470, Dec. 20,
1976; Amdt. 27–23, 53 FR 34213, Sept. 2, 1988]
O
IL
S
YSTEM
§ 27.1011
Engines: 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 of each
system may not be less than the prod-
uct of the endurance of the rotorcraft
under critical operating conditions and
the maximum oil consumption of the
engine under the same conditions, plus
a suitable margin to ensure adequate
circulation and cooling. Instead of a ra-
tional analysis of endurance and con-
sumption, a usable oil capacity of one
gallon for each 40 gallons of usable fuel
may be used.
(c) The oil cooling provisions for each
engine must be able to maintain the oil
inlet temperature to that engine at or
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Federal Aviation Administration, DOT
§ 27.1021
below the maximum established value.
This must be shown by flight tests.
[Doc. No. 5074, 29 FR 15695, Nov. 24, 1964, as
amended by Amdt. 27–23, 53 FR 34213, Sept. 2,
1988]
§ 27.1013
Oil tanks.
Each oil tank must be designed and
installed so that—
(a) It can withstand, without failure,
each vibration, inertia, fluid, and
structural load expected in operation;
(b) [Reserved]
(c) Where used with a reciprocating
engine, it has an expansion space of not
less than the greater of 10 percent of
the tank capacity or 0.5 gallon, and
where used with a turbine engine, it
has an expansion space of not less than
10 percent of the tank capacity.
(d) It is impossible to fill the tank
expansion space inadvertently with the
rotorcraft in the normal ground atti-
tude;
(e) Adequate venting is provided; and
(f) There are means in the filler open-
ing to prevent oil overflow from enter-
ing the oil tank compartment.
[Doc. No. 5074, 29 FR 15695, Nov. 24, 1964, as
amended by Amdt. 27–9, 39 FR 35461, Oct. 1,
1974]
§ 27.1015
Oil tank tests.
Each oil tank must be designed and
installed so that it can withstand,
without leakage, an internal pressure
of 5 p.s.i., except that each pressurized
oil tank used with a turbine engine
must be designed and installed so that
it can withstand, without leakage, an
internal pressure of 5 p.s.i., plus the
maximum operating pressure of the
tank.
[Amdt. 27–9, 39 FR 35462, Oct. 1, 1974]
§ 27.1017
Oil lines and fittings.
(a) Each oil line must be supported to
prevent excessive vibration.
(b) Each oil line connected to compo-
nents of the rotorcraft between which
relative motion could exist must have
provisions for flexibility.
(c) Flexible hose must be approved.
(d) Each oil line must have an inside
diameter of not less than the inside di-
ameter of the engine inlet or outlet. No
line may have splices between connec-
tions.
§ 27.1019
Oil strainer or filter.
(a) Each turbine engine installation
must incorporate an oil strainer or fil-
ter through which all of the engine oil
flows and which meets the following re-
quirements:
(1) Each oil strainer or filter that has
a bypass must be constructed and in-
stalled so that oil will flow at the nor-
mal rate through the rest of the sys-
tem with the strainer or filter com-
pletely blocked.
(2) The oil strainer or filter must
have the capacity (with respect to op-
erating limitations established for the
engine) to ensure that engine oil sys-
tem functioning is not impaired when
the oil is contaminated to a degree
(with respect to particle size and den-
sity) that is greater than that estab-
lished for the engine under Part 33 of
this chapter.
(3) The oil strainer or filter, unless it
is installed at an oil tank outlet, must
incorporate a means to indicate con-
tamination before it reaches the capac-
ity established in accordance with
paragraph (a)(2) of this section.
(4) The bypass of a strainer or filter
must be constructed and installed so
that the release of collected contami-
nants is minimized by appropriate lo-
cation of the bypass to ensure that col-
lected contaminants are not in the by-
pass flow path.
(5) An oil strainer or filter that has
no bypass, except one that is installed
at an oil tank outlet, must have a
means to connect it to the warning
system required in § 27.1305(r).
(b) Each oil strainer or filter in a
powerplant installation using recipro-
cating engines must be constructed and
installed so that oil will flow at the
normal rate through the rest of the
system with the strainer or filter ele-
ment completely blocked.
[Amdt. 27–9, 39 FR 35462, Oct. 1, 1974, as
amended by Amdt. 27–20, 49 FR 6849, Feb. 23,
1984; Amdt. 27–23, 53 FR 34213, Sept. 2, 1988]
§ 27.1021
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
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