title-14-part-27-sec27-993

537

Federal Aviation Administration, DOT

§ 27.993

not less than 2 percent of the tank ca-
pacity. It must be impossible to fill the
fuel tank expansion space inadvert-
ently with the rotorcraft in the normal
ground attitude.

[Amdt. 27–23, 53 FR 34213, Sept. 2, 1988]

§ 27.971

Fuel tank sump.

(a) Each fuel tank must have a drain-

able sump with an effective capacity in
any ground attitude to be expected in
service of 0.25 percent of the tank ca-
pacity or

⁄

gallon, whichever is great-

er, unless—

(1) The fuel system has a sediment

bowl or chamber that is accessible for
preflight drainage and has a minimum
capacity of 1 ounce for every 20 gallons
of fuel tank capacity; and

(2) Each fuel tank drain is located so

that in any ground attitude to be ex-
pected in service, water will drain from
all parts of the tank to the sediment
bowl or chamber.

(b) Each sump, sediment bowl, and

sediment chamber drain required by
this section must comply with the
drain provisions of § 27.999(b).

[Amdt. 27–23, 53 FR 34213, Sept. 2, 1988]

§ 27.973

Fuel tank filler connection.

(a) Each fuel tank filler connection

must prevent the entrance of fuel into
any part of the rotorcraft other than
the tank itself during normal oper-
ations and must be crash resistant dur-
ing a survivable impact in accordance
with § 27.952(c). In addition—

(1) Each filler must be marked as pre-

scribed in § 27.1557(c)(1);

(2) Each recessed filler connection

that can retain any appreciable quan-
tity of fuel must have a drain that dis-
charges clear of the entire rotorcraft;
and

(3) Each filler cap must provide a

fuel-tight seal under the fluid pressure
expected in normal operation and in a
survivable impact.

(b) Each filler cap or filler cap cover

must warn when the cap is not fully
locked or seated on the filler connec-
tion.

[Doc. No. 26352, 59 FR 50387, Oct. 3, 1994]

§ 27.975

Fuel tank vents.

(a) Each fuel tank must be vented

from the top part of the expansion

space so that venting is effective under
all normal flight conditions. Each vent
must minimize the probability of stop-
page by dirt or ice.

(b) The venting system must be de-

signed to minimize spillage of fuel
through the vents to an ignition source
in the event of a rollover during land-
ing, ground operation, or a survivable
impact.

[Doc. No. 5074, 29 FR 15695, Nov. 24, 1964, as
amended by Amdt. 27–23, 53 FR 34213, Sept. 2,
1988; Amdt. 27–30, 59 FR 50387, Oct. 3, 1994;
Amdt. 27–35, 63 FR 43285, Aug. 12, 1998]

§ 27.977

Fuel tank outlet.

(a) There must be a fuel stainer for

the fuel tank outlet or for the booster
pump. This strainer must—

(1) For reciprocating engine powered

rotorcraft, have 8 to 16 meshes per
inch; and

(2) For turbine engine powered rotor-

craft, prevent the passage of any object
that could restrict fuel flow or damage
any fuel system component.

(b) The clear area of each fuel tank

outlet strainer must be at least five
times the area of the outlet line.

must be at least that of the fuel tank
outlet.

(d) Each finger strainer must be ac-

cessible for inspection and cleaning.

[Amdt. 27–11, 41 FR 55470, Dec. 20, 1976]

UEL

YSTEM

OMPONENTS

§ 27.991

Fuel pumps.

Compliance with § 27.955 may not be

jeopardized by failure of—

(a) Any one pump except pumps that

are approved and installed as parts of a
type certificated engine; or

(b) Any component required for pump

operation except, for engine driven
pumps, the engine served by that
pump.

[Amdt. 27–23, 53 FR 34213, Sept. 2, 1988]

§ 27.993

Fuel system lines and fittings.

(a) Each fuel line must be installed

and supported to prevent excessive vi-
bration and to withstand loads due to
fuel pressure and accelerated flight
conditions.

(b) Each fuel line connected to com-

ponents of the rotorcraft between

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538

14 CFR Ch. I (1–1–24 Edition)

§ 27.995

which relative motion could exist must
have provisions for flexibility.

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.

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;

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]

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.

engine must be able to maintain the oil
inlet temperature to that engine at or

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