9.6.1 The requirements of this section are based
on the premise that:
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.1 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.
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.2 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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.3 The lift devices, for the purposes 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 shall be
of adequate strength and stiffness. The design data, calculations
and trials, where necessary, shall establish 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.
9.6.3 The design of propulsion and lift devices
shall 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 they are subjected to spray,
debris, salt, sand, icing, etc.
9.6.4 The design data and testing of propulsion
and lift devices shall pay due regard, as appropriate, to any pressure
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 Appropriate arrangements shall be made to
ensure that:
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.1 ingestion of debris or foreign matter is minimised;
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.2 the possibility of injury to personnel from
shafting or rotating parts is minimised; and
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.3 where necessary, inspection and removal of
debris can be carried out safely in service.