Page 152 - The Jet Engine

Controls and instrumentation

Fig. 12-9 Oil temperature and pressure transmitters and indicators.

total fuel used in gallons, pounds or kilogrammes per
hour (fig. 12-10). The transmitter measures the fuel
flow electrically and an associated electronic unit
gives a signal to the indicator proportional to the fuel
flow.
Vibration
44. A turbo-jet engine has an extremely low
vibration level and a change of vibration, due to an
impending or partial failure, may pass without being
noticed. Many engines are therefore fitted with
vibration indicators that continually monitor the
vibration level of the engine. The indicator is usually
a milliammeter that receives signals through an
amplifier from engine mounted transmitters (fig. 12-
11).
45. A vibration transmitter is mounted on the engine
casing and electrically connected to the amplifier and
indicator. The vibration sensing element is usually an
electro-magnetic transducer that converts the rate of
vibration into electrical signals and these cause the
indicator pointer to move proportional to the vibration
level. A warning lamp on the instrument panel is
incorporated in the system to warn the pilot if an
unacceptable level of vibration is approached,
Fig. 12-10 Fuel flow transmitter and enabling the engine to be shut down and so reduce
indicator. the risk of damage.

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