Section 27.971

14 CFR Ch. I (1-1-19 Edition)

not less than 2 percent of the tank capacity. It must be impossible to fill the
fuel tank expansion space inadvertently with the rotorcraft in the normal
ground attitude.
[Amdt. 27-23, 53 FR 34213, Sept. 2, 1988]

Section 27.971 Fuel tank sump.
(a) Each fuel tank must have a drainable sump with an effective capacity in
any ground attitude to be expected in
service of 0.25 percent of the tank capacity or 1-16 gallon, whichever is greater, 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 expected 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 Section 27.999(b).
[Amdt. 27-23, 53 FR 34213, Sept. 2, 1988]

Section 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 operations and must be crash resistant during a survivable impact in accordance
with Section 27.952(c). In addition - 
(1) Each filler must be marked as prescribed in Section 27.1557(c)(1);
(2) Each recessed filler connection
that can retain any appreciable quantity of fuel must have a drain that discharges 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 connection.
spaschal on DSK3GDR082PROD with CFR

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

Section 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 stoppage by dirt or ice.
(b) The venting system must be designed to minimize spillage of fuel
through the vents to an ignition source
in the event of a rollover during landing, 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]

Section 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 rotorcraft, 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.
(c) The diameter of each strainer
must be at least that of the fuel tank
outlet.
(d) Each finger strainer must be accessible for inspection and cleaning.
[Amdt. 27-11, 41 FR 55470, Dec. 20, 1976]

FUEL SYSTEM COMPONENTS
Section 27.991 Fuel pumps.
Compliance with Section 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]

Section 27.993 Fuel system lines and fittings.
(a) Each fuel line must be installed
and supported to prevent excessive vibration and to withstand loads due to
fuel pressure and accelerated flight
conditions.
(b) Each fuel line connected to components of the rotorcraft between

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