Page 270 - The Jet Engine

Maintenance

that the maximum temperature limitation is not 39. Throttle movements should be kept to a
exceeded. If the temperature limitation appears likely minimum and be smooth and progressive to avoid
to be exceeded, the shut-off valve must be closed thermal stresses associated with rapid changes in
and the starting cycle cancelled; the cause and temperature. Rapid throttle movements to check the
possible effect of the high temperature must then be acceleration and deceleration capabilities of the
investigated before the engine is again started. engine should be made only after all other major
checks have proved satisfactory and after some
38. When a turbo-propeller engine is being started, slower accelerations and decelerations have proved
the propeller must be set to the correct starting pitch, successful.
as recommended by the engine manufacturer. To
provide the minimum resistance to turning and thus 40. Before an engine is stopped, it should normally
prevent an excessive exhaust gas temperature be allowed to run for a short period at idling speed to
occurring during the starting cycle, some propellers ensure gradual cooling of the turbine assembly. The
have a special fine pitch setting. only action required to stop the engine is the closing

Fig. 24-9 Overheated turbine blades.

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