title-14-part-27-sec27-1329

550

14 CFR Ch. I (1–1–24 Edition)

§ 27.1327

the alternate static pressure system,
differs from the reading of the altim-
eter when on the primary static system
by more than 50 feet, a correction card
must be provided for the alternate
static system.

(d) of this section, if the static pressure
system incorporates both a primary
and an alternate static pressure source,
the means for selecting one or the
other source must be designed so
that—

(1) When either source is selected, the

other is blocked off; and

(2) Both sources cannot be blocked

off simultaneously.

(d) For unpressurized rotorcraft,

paragraph (c)(1) of this section does not
apply if it can be demonstrated that
the static pressure system calibration,
when either static pressure source is
selected is not changed by the other
static pressure source being open or
blocked.

(Secs. 313(a), 601, 603, 604, and 605 of the Fed-
eral Aviation Act of 1958 (49 U.S.C. 1354(a),
1421, 1423, 1424, and 1425); and sec. 6(c) of the
Dept. of Transportation Act (49 U.S.C.
1655(c)))

[Doc. No. 5074, 29 FR 15695, Nov. 24, 1964, as
amended by Amdt. 27–13, 42 FR 36972, July 18,
1977]

§ 27.1327

Magnetic direction indicator.

(a) Except as provided in paragraph

(b) of this section—

(1) Each magnetic direction indicator

must be installed so that its accuracy
is not excessively affected by the
rotorcraft’s vibration or magnetic
fields; and

(2) The compensated installation may

not have a deviation, in level flight,
greater than 10 degrees on any heading.

(b) A magnetic nonstabilized direc-

tion indicator may deviate more than
10 degrees due to the operation of elec-
trically powered systems such as elec-
trically heated windshields if either a
magnetic stabilized direction indi-
cator, which does not have a deviation
in level flight greater than 10 degrees
on any heading, or a gyroscopic direc-
tion indicator, is installed. Deviations
of a magnetic nonstabilized direction
indicator of more than 10 degrees must

be placarded in accordance with
§ 27.1547(e).

(Secs. 313(a), 601, 603, 604, and 605 of the Fed-
eral Aviation Act of 1958 (49 U.S.C. 1354(a),
1421, 1423, 1424, and 1425); and sec. 6(c) of the
Dept. of Transportation Act (49 U.S.C.
1655(c)))

[Amdt. 27–13, 42 FR 36972, July 18, 1977]

§ 27.1329

Automatic pilot and flight

guidance system.

For the purpose of this subpart, an

automatic pilot and flight guidance
system may consist of an autopilot,
flight director, or a component that
interacts with stability augmentation
or trim.

(a) Each automatic pilot and flight

guidance system must be designed so
that it:

(1) Can be overpowered by one pilot

to allow control of the rotorcraft;

(2) Provides a means to disengage the

system, or any malfunctioning compo-
nent of the system, by each pilot to
prevent it from interfering with the
control of the rotorcraft; and

(3) Provides a means to indicate to

the flight crew its current mode of op-
eration. Selector switch position is not
acceptable as a means of indication.

(b) Unless there is automatic syn-

chronization, each system must have a
means to readily indicate to the pilot
the alignment of the actuating device
in relation to the control system it op-
erates.

for the system’s operation must be
readily accessible to the pilots.

(d) The system must be designed so

that, within the range of adjustment
available to the pilot, it cannot
produce hazardous loads on the rotor-
craft, or create hazardous deviations in
the flight path, under any flight condi-
tion appropriate to its use or in the
event of a malfunction, assuming that
corrective action begins within a rea-
sonable period of time.

(e) If the automatic pilot and flight

guidance system integrates signals
from auxiliary controls or furnishes
signals for operation of other equip-
ment, there must be a means to pre-
vent improper operation.

(f) If the automatic pilot system can

be coupled to airborne navigation
equipment, means must be provided to

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§ 27.1351

indicate to the pilots the current mode
of operation. Selector switch position
is not acceptable as a means of indica-
tion.

[Amdt. 27–21, 49 FR 44435, Nov. 6, 1984, as
amended by Amdt. 27–35, 63 FR 43285, Aug. 12,
1998; Amdt. 27–51, 88 FR 8738, Feb. 10, 2023]

§ 27.1337

Powerplant instruments.

(a)

Instruments and instrument lines.

(1) Each powerplant instrument line
must meet the requirements of §§ 27.-
961 and 27.993.

(2) Each line carrying flammable

fluids under pressure must—

(i) Have restricting orifices or other

safety devices at the source of pressure
to prevent the escape of excessive fluid
if the line fails; and

(ii) Be installed and located so that

the escape of fluids would not create a
hazard.

(3) Each powerplant instrument that

utilizes flammable fluids must be in-
stalled and located so that the escape
of fluid would not create a hazard.

(b)

Fuel quantity indicator. Each fuel

quantity indicator must be installed to
clearly indicate to the flight crew the
quantity of fuel in each tank in flight.
In addition—

(1) Each fuel quantity indicator must

be calibrated to read ‘‘zero’’ during
level flight when the quantity of fuel
remaining in the tank is equal to the
unusable fuel supply determined under
§ 27.959;

(2) When two or more tanks are close-

ly interconnected by a gravity feed sys-
tem and vented, and when it is impos-
sible to feed from each tank sepa-
rately, at least one fuel quantity indi-
cator must be installed; and

(3) Each exposed sight gauge used as

a fuel quantity indicator must be pro-
tected against damage.

(c)

Fuel flowmeter system. If a fuel

flowmeter system is installed, each
metering component must have a
means for bypassing the fuel supply if
malfunction of that component se-
verely restricts fuel flow.

(d)

Oil quantity indicator. There must

be means to indicate the quantity of
oil in each tank—

(1) On the ground (including during

the filling of each tank); and

(2) In flight, if there is an oil transfer

system or reserve oil supply system.

(e) Rotor drive system transmissions

and gearboxes utilizing ferromagnetic
materials must be equipped with chip
detectors designed to indicate the pres-
ence of ferromagnetic particles result-
ing from damage or excessive wear.
Chip detectors must—

(1) Be designed to provide a signal to

the device required by § 27.1305(v) and
be provided with a means to allow
crewmembers to check, in flight, the
function of each detector electrical cir-
cuit and signal.

(2) [Reserved]

(Secs. 313(a), 601, and 603, 72 Stat. 752, 775, 49
U.S.C. 1354(a), 1421, and 1423; sec. 6(c) 49
U.S.C. 1655(c))

[Doc. No. 5074, 29 FR 15695, Nov. 24, 1964, as
amended by Amdt. 27–12, 42 FR 15046, Mar. 17,
1977; Amdt. 27–23, 53 FR 34214, Sept. 2, 1988;
Amdt. 27–37, 64 FR 45095, Aug. 18, 1999]

LECTRICAL

YSTEMS AND

QUIPMENT

§ 27.1351

General.

(a)

Electrical system capacity. Elec-

trical equipment must be adequate for
its intended use. In addition—

(1) Electric power sources, their

transmission cables, and their associ-
ated control and protective devices
must be able to furnish the required
power at the proper voltage to each
load circuit essential for safe oper-
ation; and

(2) Compliance with paragraph (a)(1)

of this section must be shown by an
electrical load analysis, or by elec-
trical measurements that take into ac-
count the electrical loads applied to
the electrical system, in probable com-
binations and for probable durations.

(b)

Function. For each electrical sys-

tem, the following apply:

(1) Each system, when installed,

must be—

(i) Free from hazards in itself, in its

method of operation, and in its effects
on other parts of the rotorcraft; and

(ii) Protected from fuel, oil, water,

other detrimental substances, and me-
chanical damage.

(2) Electric power sources must func-

tion properly when connected in com-
bination or independently.

(3) No failure or malfunction of any

source may impair the ability of any
remaining source to supply load cir-
cuits essential for safe operation.