Page 259 - The Jet Engine

Power plant installation

Fig. 23-12 Engine accessibility,
turbo-fan engine.

14. The jet pipe is normally attached to the rear of
the engine and supported by the engine mountings. Fig. 23-13 Engine accessibility,
In some installations, particularly where long jet turbo-propeller engine.
pipes are employed, an additional mounting is
provided, usually in the form of small rollers attached
to each side of the jet pipe. The rollers locate in water injection pumps, are driven by air tapped from
airframe-mounted channels and support the weight the engine compressor. Air conditioning and cabin
of the jet pipe, whilst still allowing it to freely expand pressurization units may have a separate air-driven
in a longitudinal direction.
compressor or use air direct from the engine
ACCESSORIES compressor. The amount of air that is taken for all
accessories and services must always be a very
15. An aircraft power plant installation generally small percentage of the total airflow, as it represents
includes a number of accessories that are electrical- a thrust or power loss and an increase in specific fuel
ly operated, mechanically driven or driven by high consumption.
pressure air.
COWLINGS
16. Electrically operated accessories such as
engine control actuators, amplifiers, air control 19. Access to an engine mounted in the wing or
valves and solenoids, are supplied with power from fuselage is by hinged doors; on pod and turbo-
the aircraft electrical system or an engine driven propeller installations the main cowlings are hinged.
dedicated electrical generator. Access for minor servicing is by small detachable or
17. Mechanically driven units, such as generators, hinged panels. All fasteners are of the quick-release
constant speed drive units, hydraulic pumps, low and type.
high pressure fuel pumps, and engine speed 20. A turbo-propeller engine, or a turbo-jet engine
signalling, measuring or governing units are driven
from the engine through internal and external mounted in a pod, is usually far more accessible than
gearboxes (Part 7). a buried engine because of the larger area of hinged
cowling that can be provided. The accessibility of a
18. Air-driven accessories, such as the air starter podded turbo-fan engine is shown in fig, 23-12 and
and possibly the thrust reverser, afterburner and that of a turbo-propeller engine is shown in fig, 23-13.

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