808 

14 CFR Ch. I (1–1–14 Edition) 

§ 29.1333 

(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) Only the required flight instru-

ments for the first pilot may be con-
nected to that operating 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] 

§ 29.1335

Flight director systems. 

If a flight director system is in-

stalled, means must be provided to in-

dicate to the flight crew its current 
mode of operation. Selector switch po-
sition is not acceptable as a means of 
indication. 

(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), Dept. 
of Transportation Act (49 U.S.C. 1655(c))) 

[Amdt. 29–14, 42 FR 36973, July 18, 1977] 

§ 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; 

(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; 

(3) Tanks with interconnected outlets 

and airspaces may be treated as one 
tank and need not have separate indi-
cators; and 

(4) 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. 

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