9.6.1 The requirements of this section are based
on the premises that:
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(a) Propulsion arrangements and lift arrangements
may be provided by separate devices, or be integrated into a single
propulsion and lift device. Propulsion devices may be air, or water
propellers or water jets and the requirements apply to all types of
craft, whereas lift devices apply only to air-cushion vehicles.
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(b) Propulsion devices are those which directly
provide the propulsive thrust and include machinery items and any
associated ducts, vanes, scoops and nozzles, the primary function
of which is to contribute to the propulsive thrust.
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(c) The lift devices, for the purpose of this
section, are those items of machinery which directly raise the pressure
of the air and move it for the primary purpose of providing lifting
force for an air-cushion vehicle.
9.6.2 The propulsion and lift devices should be
of adequate strength and stiffness. The Administration should be satisfied
with the design data and such calculations as are made and where necessary
should establish by suitable tests the ability of the device to withstand
the loads which can arise during the operations for which the craft
is to be certificated, so that the possibility of catastrophic failure
is extremely remote footnote.
9.6.3 The design of propulsion and lift devices
should pay due regard to the effects of allowable corrosion, electrolytic
action between different metals, erosion or cavitation which may result
from operation in environments in which it is subjected to spray,
debris, salt, sand, icing, etc.
9.6.4 The design data and testing of propulsion
and lift devices should pay due regard, as appropriate, to any pressures
which could be developed as a result of a duct blockage, to steady
and cyclic loadings, to loadings due to external forces and to the
use of the devices in manoeuvring and reversing and to the axial location
of rotating parts.
9.6.5 The Administration should be satisfied with
the arrangements as appropriate to ensure that:
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(a) ingestion of debris or foreign matter is minimized;
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(b) the possibility of injury to personnel from
shafting or rotating parts is minimized; and
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(c) where necessary, inspection and removal of
debris can be carried out safely in service.