spaschal on DSK3GDR082PROD with CFR

Federal Aviation Administration, DOT

Section 25.1309

continuous operation nor designed to
prevent hazard if it failed.
(5) An indicator to indicate the functioning of the powerplant ice protection system for each engine.
(6) An indicator for the fuel strainer
or filter required by Section 25.997 to indicate
the occurrence of contamination of the
strainer or filter before it reaches the
capacity established in accordance
with Section 25.997(d).
(7) A warning means for the oil
strainer or filter required by Section 25.1019, if
it has no bypass, to warn the pilot of
the occurrence of contamination of the
strainer or filter screen before it
reaches the capacity established in accordance with Section 25.1019(a)(2).
(8) An indicator to indicate the proper functioning of any heater used to
prevent ice clogging of fuel system
components.
(d) For turbojet engine powered airplanes. In addition to the powerplant
instruments required by paragraphs (a)
and (c) of this section, the following
powerplant instruments are required:
(1) An indicator to indicate thrust, or
a parameter that is directly related to
thrust, to the pilot. The indication
must be based on the direct measurement of thrust or of parameters that
are directly related to thrust. The indicator must indicate a change in thrust
resulting from any engine malfunction,
damage, or deterioration.
(2) A position indicating means to indicate to the flightcrew when the
thrust reversing device - 
(i) Is not in the selected position, and
(ii) Is in the reverse thrust position,
for each engine using a thrust reversing device.
(3) An indicator to indicate rotor system unbalance.
(e) For turbopropeller-powered airplanes. In addition to the powerplant
instruments required by paragraphs (a)
and (c) of this section, the following
powerplant instruments are required:
(1) A torque indicator for each engine.
(2) Position indicating means to indicate to the flight crew when the propeller blade angle is below the flight
low pitch position, for each propeller.
(f) For airplanes equipped with fluid
systems (other than fuel) for thrust or
power augmentation, an approved

means must be provided to indicate the
proper functioning of that system to
the flight crew.
[Amdt. 25-23, 35 FR 5678, Apr. 8, 1970, as
amended by Amdt. 25-35, 39 FR 1831, Jan. 15,
1974; Amdt. 25-36, 39 FR 35461, Oct. 1, 1974;
Amdt. 25-38, 41 FR 55467, Dec. 20, 1976; Amdt.
25-54, 45 FR 60173, Sept. 11, 1980; Amdt. 25-72,
55 FR 29785, July 20, 1990; Amdt. 25-115, 69 FR
40527, July 2, 2004]

Section 25.1307 Miscellaneous equipment.
The following is required miscellaneous equipment:
(a) [Reserved]
(b) Two or more independent sources
of electrical energy.
(c) Electrical protective devices, as
prescribed in this part.
(d) Two systems for two-way radio
communications, with controls for
each accessible from each pilot station,
designed and installed so that failure of
one system will not preclude operation
of the other system. The use of a common antenna system is acceptable if
adequate reliability is shown.
(e) Two systems for radio navigation,
with controls for each accessible from
each pilot station, designed and installed so that failure of one system
will not preclude operation of the other
system. The use of a common antenna
system is acceptable if adequate reliability is shown.
[Amdt. 25-23, 35 FR 5678, Apr. 8, 1970, as
amended by Amdt. 25-46, 43 FR 50598, Oct. 30,
1978; Amdt. 25-54, 45 FR 60173, Sept. 11, 1980;
Amdt. 25-72, 55 FR 29785, July 20, 1990]

Section 25.1309 Equipment, systems, and installations.
(a) The equipment, systems, and installations whose functioning is required by this subchapter, must be designed to ensure that they perform
their intended functions under any
foreseeable operating condition.
(b) The airplane systems and associated components, considered separately and in relation to other systems,
must be designed so that - 
(1) The occurrence of any failure condition which would prevent the continued safe flight and landing of the airplane is extremely improbable, and
(2) The occurrence of any other failure conditions which would reduce the
capability of the airplane or the ability

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