Code of Federal Regulations - Title 14

182

14 CFR Ch. I (1–1–14 Edition)

Pt. 23, SFAR No. 23

ground operation must be designed so that
no single failure or malfunction of the sys-
tem will result in unwanted reverse thrust
under any expected operating condition.
Failure of structural elements need not be
considered if the probability of this kind of
failure is extremely remote.

(b) Turbopropeller reversing systems in-

tended for in-flight use must be designed so
that no unsafe condition will result during
normal operation of the system, or from any
failure (or reasonably likely combination of
failures) of the reversing system, under any
anticipated condition of operation of the air-
plane. Failure of structural elements need
not be considered if the probability of this
kind of failure is extremely remote.

shown by failure analysis, testing, or both
for propeller systems that allow propeller
blades to move from the flight low-pitch po-
sition to a position that is substantially less
than that at the normal flight low-pitch stop
position. The analysis may include or be sup-
ported by the analysis made to show compli-
ance with the type certification of the pro-
peller and associated installation compo-
nents. Credit will be given for pertinent
analysis and testing completed by the engine
and propeller manufacturers.

40.

Turbopropeller drag-limiting systems. Tur-

bopropeller drag-limiting systems must be
designed so that no single failure or malfunc-
tion of any of the systems during normal or
emergency operation results in propeller
drag in excess of that for which the airplane
was designed. Failure of structural elements
of the drag-limiting systems need not be con-
sidered if the probability of this kind of fail-
ure is extremely remote.

41.

Turbine engine powerplant operating

characteristics. For turbopropeller powered
airplanes, the turbine engine powerplant op-
erating characteristics must be investigated
in flight to determine that no adverse char-
acteristics (such as stall, surge, or flameout)
are present to a hazardous degree, during
normal and emergency operation within the
range of operating limitations of the air-
plane and of the engine.

42.

Fuel flow. (a) For turbopropeller pow-

ered airplanes—

(1) The fuel system must provide for con-

tinuous supply of fuel to the engines for nor-
mal operation without interruption due to
depletion of fuel in any tank other than the
main tank; and

(2) The fuel flow rate for turbopropeller en-

gine fuel pump systems must not be less
than 125 percent of the fuel flow required to
develop the standard sea level atmospheric
conditions takeoff power selected and in-
cluded as an operating limitation in the Air-
plane Flight Manual.

(b) For reciprocating engine powered air-

planes, it is acceptable for the fuel flow rate
for each pump system (main and reserve sup-

ply) to be 125 percent of the takeoff fuel con-
sumption of the engine.

UEL

YSTEM

OMPONENTS

43.

Fuel pumps. For turbopropeller powered

airplanes, a reliable and independent power
source must be provided for each pump used
with turbine engines which do not have pro-
visions for mechanically driving the main
pumps. It must be demonstrated that the
pump installations provide a reliability and
durability equivalent to that provided by
FAR 23.991(a).

44.

Fuel strainer or filter. For turbopropeller

powered airplanes, the following apply:

(a) There must be a fuel strainer or filter

between the tank outlet and the fuel meter-
ing device of the engine. In addition, the fuel
strainer or filter must be—

(1) Between the tank outlet and the en-

gine-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 remov-
able; and

(3) Mounted so that its weight is not sup-

ported 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 sys-

tem to prevent the accumulation of ice on
the filter, there must be means to automati-
cally maintain the fuel flow if ice-clogging of
the filter occurs; and

adequate capacity (with respect to operating
limitations established to insure proper serv-
ice) and of appropriate mesh to insure proper
engine operation, with the fuel contaminated
to a degree (with respect to 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.

OOLING

46.

Cooling test procedures for turbopropeller

powered airplanes. (a) Turbopropeller powered
airplanes must be shown to comply with the
requirements of FAR 23.1041 during takeoff,
climb en route, and landing stages of flight
that correspond to the applicable perform-
ance requirements. The cooling test must be
conducted with the airplane in the configu-
ration 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

F. per minute.

(b) Temperatures must be stabilized under

the conditions from which entry is made into

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