PART I-DESCRIPTIVE
instability of flow, i.e. surge, the surplus air is bled off
through air-bleed valves and the guide vanes are held in
the maximum swirl position. When the normal flight
r.p.m. are reached, the air-bleed valves arc closed and
the guide vanes move progressively to the minimum
swirl position which occurs at 7,200 r.p.m.
(b) No noticeable change in r.p.m. or thrust occurs when the
air-bleeds change over, nor do the guide vanes have any
noticeable effect on engine operation. However, until
the guide vanes reach the minimum swirl position at
about 7,200 r.p.m. the compressor is not operating at
maximum efficiency.
13. Engine instruments and anti-icing control
(a) The tachometer, jet pipe temperature gauge and oil
pressure gauge are grouped on the starboard side of the
instrument panel.
(b) Anti-icing control
NOTE.-Use of this system is at present prohibited.
The on/off switch (11) for the automatic anti-icing
system is on the port wall. When set to on, hot air is bled
from the engine and fed to the engine intakes. The system
is intended only for icing prevention and is not intended
for de-icing purposes.
MAIN SERVICES
16. Electrical system (24 volt)
(a) D.C. supply
(i) Two 6,000-watt engine-driven generators supply the
whole of the electrical system and charge a single
24 volt aircraft battery. Two magnetic indicators,
(55) one for each generator, on the upper starboard
coaming show white when their respective generator
is not supplying power. Generator cut-in speed is
approximately 1,900 r.p.m. 19
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