Page 285 - The Jet Engine

Overhaul

schedule. These tests cover such characteristics as
anti-icing, combustion and reheat efficiencies,
performance, mechanical reliability, and oil and fuel
consumptions at the variety of conditions to which
the engine may be subjected during its operational
life. Flight evaluation testing can be effected by
installing the engine in an aircraft or in an altitude test
cell (fig. 25-13) to test the variations of air humidity,
pressure and temperature on the engine, its
accessories and the oil and fuel systems. When in an
aircraft, the engine is operated at the actual
atmospheric conditions specified in the schedule, but
in an altitude test cell, the engine is installed in an Fig. 25-15 Transportation stand and storage
enclosed cell and tested to the schedule in bag.
conditions that are mechanically simulated.

58. Mechanical simulation comprises supplying the
engine inlet with an accurately controlled mass the hot gas would be directed upwards at a low
airflow at the required temperature and humidity, and velocity.
adjusting the atmospheric pressure within the
exhaust cell to coincide with pressure at varying Preparing for storage/despatch
altitudes. 61. The preparation of the engine/module for
storage and/or despatch is of major importance,
59. The data which is accumulated from either 'sea- since storage and transportation calls for special
level' or altitude testing is retained for future treatment to preserve the engine. To resist corrosion
development, engine life assessment, material capa- during storage, the fuel system is inhibited by special
bilities or any aspect of engine history. oil and all apertures are sealed off. The external and
internal surfaces of the engine are also protected by
60. During the testing of turbo-jet engines there is a special inhibiting powders or by paper impregnated
need to reduce the exhaust noise to within with inhibiting powder and the engine is enclosed in
acceptable limits. This may be achieved by several a re-usable bag (fig. 25-15) or plastic sheeting into
different means, each involving costly equipment. which a specific amount of desiccant is inserted. If
However, a typical silencer would do this by transportation by rail or sea is involved, the inhibited
expansion in the first section, damping by acoustic and bagged engine may be packed in a wooden
tubes and final diffusion by a large exit through which crate or metal case.

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