Pt. 135, App. A

14 CFR Ch. I (1-1-19 Edition)

(a) There must be a fuel strainer or filter
between the tank outlet and the fuel metering device of the engine. In addition, the fuel
strainer or filter must be - 
(1) Between the tank outlet and the engine-driven positive displacement pump
inlet, if there is an engine-driven positive
displacement pump;
(2) Accessible for drainage and cleaning
and, for the strainer screen, easily removable; and
(3) Mounted so that its weight is not supported by the connecting lines or by the
inlet or outlet connections of the strainer or
filter itself.
(b) Unless there are means in the fuel system to prevent the accumulation of ice on
the filter, there must be means to automatically maintain the fuel-flow if ice-clogging
of the filter occurs; and
(c) The fuel strainer or filter must be of
adequate capacity (for operating limitations
established to ensure proper service) and of
appropriate mesh to insure proper engine operation, with the fuel contaminated to a degree (for particle size and density) that can
be reasonably expected in service. The degree of fuel filtering may not be less than
that established for the engine type certification.
45. Lightning strike protection. Protection
must be provided against the ignition of
flammable vapors in the fuel vent system
due to lightning strikes.
Cooling
46. Cooling test procedures for turbopropeller
powered airplanes. (a) Turbopropeller powered
airplanes must be shown to comply with
FAR 23.1041 during takeoff, climb, en route,
and landing stages of flight that correspond
to the applicable performance requirements.
The cooling tests must be conducted with
the airplane in the configuration, and operating under the conditions that are critical
relative to cooling during each stage of
flight. For the cooling tests a temperature is
 - stabilized -  when its rate of change is less
than 2 SectionF. per minute.
(b) Temperatures must be stabilized under
the conditions from which entry is made into
each stage of flight being investigated unless
the entry condition is not one during which
component and engine fluid temperatures
would stabilize, in which case, operation
through the full entry condition must be
conducted before entry into the stage of
flight being investigated to allow temperatures to reach their natural levels at the
time of entry. The takeoff cooling test must
be preceded by a period during which the
powerplant component and engine fluid temperatures are stabilized with the engines at
ground idle.
(c) Cooling tests for each stage of flight
must be continued until - 

(1) The component and engine fluid temperatures stabilize;
(2) The stage of flight is completed; or
(3) An operating limitation is reached.
Induction System
47. Air induction. For turbopropeller powered airplanes - 
(a) There must be means to prevent hazardous quantities of fuel leakage or overflow
from drains, vents, or other components of
flammable fluid systems from entering the
engine intake systems; and
(b) The air inlet ducts must be located or
protected so as to minimize the ingestion of
foreign matter during takeoff, landing, and
taxiing.
48. Induction system icing protection. For
turbopropeller powered airplanes, each turbine engine must be able to operate throughout its flight power range without adverse
effect on engine operation or serious loss of
power or thrust, under the icing conditions
specified in appendix C of part 25 of this
chapter. In addition, there must be means to
indicate to appropriate flight crewmembers
the functioning of the powerplant ice protection system.
49. Turbine engine bleed air systems. Turbine
engine bleed air systems of turbopropeller
powered airplanes must be investigated to
determine - 
(a) That no hazard to the airplane will result if a duct rupture occurs. This condition
must consider that a failure of the duct can
occur anywhere between the engine port and
the airplane bleed service; and
(b) That, if the bleed air system is used for
direct cabin pressurization, it is not possible
for hazardous contamination of the cabin air
system to occur in event of lubrication system failure.
Exhaust System
50. Exhaust system drains. Turbopropeller
engine exhaust systems having low spots or
pockets must incorporate drains at those locations. These drains must discharge clear of
the airplane in normal and ground attitudes
to prevent the accumulation of fuel after the
failure of an attempted engine start.
Powerplant Controls and Accessories
51. Engine controls. If throttles or power levers for turbopropeller powered airplanes are
such that any position of these controls will
reduce the fuel flow to the engine(s) below
that necessary for satisfactory and safe idle
operation of the engine while the airplane is
in flight, a means must be provided to prevent inadvertent movement of the control
into this position. The means provided must
incorporate a positive lock or stop at this
idle position and must require a separate and
distinct operation by the crew to displace

522

VerDate Sep<11>2014

08:20 May 17, 2019

Jkt 247048

PO 00000

Frm 00532

Fmt 8010

Sfmt 8002

Y:\SGML\247048.XXX

247048