Federal Aviation Administration, DOT

Pt. 135, App. A

the control from the normal engine operating range.
52. Reverse thrust controls. For turbopropeller powered airplanes, the propeller reverse thrust controls must have a means to
prevent their inadvertent operation. The
means must have a positive lock or stop at
the idle position and must require a separate
and distinct operation by the crew to displace the control from the flight regime.
53. Engine ignition systems. Each turbopropeller airplane ignition system must be
considered an essential electrical load.
54. Powerplant accessories. The powerplant
accessories must meet FAR 23.1163, and if
the continued rotation of any accessory remotely driven by the engine is hazardous
when malfunctioning occurs, there must be
means to prevent rotation without interfering with the continued operation of the
engine.
Powerplant Fire Protection
55. Fire detector system. For turbopropeller
powered airplanes, the following apply:
(a) There must be a means that ensures
prompt detection of fire in the engine compartment. An overtemperature switch in
each engine cooling air exit is an acceptable
method of meeting this requirement.
(b) Each fire detector must be constructed
and installed to withstand the vibration, inertia, and other loads to which it may be
subjected in operation.
(c) No fire detector may be affected by any
oil, water, other fluids, or fumes that might
be present.
(d) There must be means to allow the flight
crew to check, in flight, the functioning of
each fire detector electric circuit.
(e) Wiring and other components of each
fire detector system in a fire zone must be at
least fire resistant.
56. Fire protection, cowling and nacelle skin.
For reciprocating engine powered airplanes,
the engine cowling must be designed and
constructed so that no fire originating in the
engine compartment can enter either
through openings or by burn through, any
other region where it would create additional hazards.
57. Flammable fluid fire protection. If flammable fluids or vapors might be liberated by
the leakage of fluid systems in areas other
than engine compartments, there must be
means to - 
(a) Prevent the ignition of those fluids or
vapors by any other equipment; or
(b) Control any fire resulting from that ignition.
Equipment
58. Powerplant instruments. (a) The following are required for turbopropeller airplanes:

(1) The instruments required by FAR
23.1305 (a) (1) through (4), (b) (2) and (4).
(2) A gas temperature indicator for each
engine.
(3) Free air temperature indicator.
(4) A fuel flowmeter indicator for each engine.
(5) Oil pressure warning means for each engine.
(6) A torque indicator or adequate means
for indicating power output for each engine.
(7) Fire warning indicator for each engine.
(8) A means to indicate when the propeller
blade angle is below the low-pitch position
corresponding to idle operation in flight.
(9) A means to indicate the functioning of
the ice protection system for each engine.
(b) For turbopropeller powered airplanes,
the turbopropeller blade position indicator
must begin indicating when the blade has
moved below the flight low-pitch position.
(c) The following instruments are required
for reciprocating engine powered airplanes:
(1) The instruments required by FAR
23.1305.
(2) A cylinder head temperature indicator
for each engine.
(3) A manifold pressure indicator for each
engine.
Systems and Equipments
General
59. Function and installation. The systems
and equipment of the airplane must meet
FAR 23.1301, and the following:
(a) Each item of additional installed equipment must - 
(1) Be of a kind and design appropriate to
its intended function;
(2) Be labeled as to its identification, function, or operating limitations, or any applicable combination of these factors, unless
misuse or inadvertent actuation cannot create a hazard;
(3) Be installed according to limitations
specified for that equipment; and
(4) Function properly when installed.
(b) Systems and installations must be designed to safeguard against hazards to the
aircraft in the event of their malfunction or
failure.
(c) Where an installation, the functioning
of which is necessary in showing compliance
with the applicable requirements, requires a
power supply, that installation must be considered an essential load on the power supply, and the power sources and the distribution system must be capable of supplying the
following power loads in probable operation
combinations and for probable durations:
(1) All essential loads after failure of any
prime mover, power converter, or energy
storage device.
(2) All essential loads after failure of any
one engine on two-engine airplanes.

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