Page 271 - The Jet Engine
P. 271
Maintenance
of the shut-off valve. The shut-off valve must not be 41. The time taken for the engine to come to rest
re-opened during engine rundown, as the resulting after the shut-off valve is closed is known as the
supply of fuel can spontaneously ignite with 'rundown time' and this can give an indication of any
consequent severe overheating of the turbine rubbing inside the engine. However it should be
assembly. An example of turbine blades which have borne in mind that variations in wind velocity and
been subjected to overheating is shown in fig. 24-9. direction may affect the run-down time of an engine.
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