660
14 CFR Ch. I (1–1–24 Edition)
§ 29.1331
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
indicate to the pilots the current mode
of operation. Selector switch position
is not acceptable as a means of indica-
tion.
[Doc. No. 5084, 29 FR 16150, Dec. 3, 1964, as
amended by Amdt. 29–24, 49 FR 44439, Nov. 6,
1984; Amdt. 29–24, 49 FR 47594, Dec. 6, 1984;
Amdt. 29–42, 63 FR 43285, Aug. 12, 1998; Amdt.
29–59, 88 FR 8739, Feb. 10, 2023]
§ 29.1331
Instruments using a power
supply.
For category A rotorcraft—
(a) Each required flight instrument
using a power supply must have—
(1) Two independent sources of power;
(2) A means of selecting either power
source; and
(3) A visual means integral with each
instrument to indicate when the power
adequate to sustain proper instrument
performance is not being supplied. The
power must be measured at or near the
point where it enters the instrument.
For electrical instruments, the power
is considered to be adequate when the
voltage is within the approved limits;
and
(b) The installation and power supply
system must be such that failure of
any flight instrument connected to one
source, or of the energy supply from
one source, or a fault in any part of the
power distribution system does not
interfere with the proper supply of en-
ergy from any other source.
[Doc. No. 5084, 29 FR 16150, Dec. 3, 1964, as
amended by Amdt. 29–24, 49 FR 44439, Nov. 6,
1984]
§ 29.1333
Instrument systems.
For systems that operate the re-
quired flight instruments which are lo-
cated at each pilot’s station, the fol-
lowing apply:
(a) For pneumatic systems, only the
required flight instruments for the
first pilot may be connected to that op-
erating system.
(b) The equipment, systems, and in-
stallations must be designed so that
one display of the information essen-
tial to the safety of flight which is pro-
vided by the flight instruments re-
mains available to a pilot, without ad-
ditional crewmember action, after any
single failure or combination of fail-
ures that are not shown to be ex-
tremely improbable.
(c) Additional instruments, systems,
or equipment may not be connected to
the operating system for a second pilot
unless provisions are made to ensure
the continued normal functioning of
the required flight instruments in the
event of any malfunction of the addi-
tional instruments, systems, or equip-
ment which is not shown to be ex-
tremely improbable.
[Amdt. 29–24, 49 FR 44439, Nov. 6, 1984, as
amended by Amdt. 29–59, 88 FR 8740, Feb. 10,
2023]
§ 29.1337
Powerplant instruments.
(a)
Instruments and instrument lines.
(1) Each powerplant and auxiliary
power unit instrument line must meet
the requirements of §§ 29.993 and 29.1183.
(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 and auxiliary
power unit instrument that utilizes
flammable fluids must be installed and
located so that the escape of fluid
would not create a hazard.
(b)
Fuel quantity indicator. There
must be means to indicate to the flight
crew members the quantity, in gallons
or equivalent units, of usable fuel in
each tank during 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
§ 29.959;
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