PART 1-DESCRIPTIVE
alongside the pushbutton. The presence of fire is
indicated by either or both warning lights coming on,
but more certainly by the latter. The fire-extinguisher
cannot be operated unless electrical power is available.
When Mod. 3524 is incorporated power is available
direct from the aircraft battery. In unmodified aircraft
the Ground Flight switch must be in the Flight position
at r.p.m. below generator cut-in speed. Above this cut-
in speed the position of the Ground Flight switch is
immaterial.
(b) Fire warning indication is subject to three different
modification states:
(i) Mod. 3238. Comprising 10 non-resetting flame
detectors in the engine bay and 8 resetting detectors
around the combustion chambers. If the fire warning
light comes on and the throttle is then closed the
warning light will remain on if a fire has occurred
but will go out if a hot gas leakage is present. If a
fire has occurred the warning light will remain on
after the fire has been extinguished.
(ii) Mod. 3475. This deletes the 8 resetting detectors in
the engine bay. If the fire warning light comes on,
it will remain on irrespective of whether the fire or hot
gas leakage is present and irrespective of any sub-
sequent action.
(iii) Mod. 3418. This replaces the 10 non-resetting
detectors with 10 resetting detectors, set to operate at
300°C. If the fire warning light comes on and the
throttle is then closed the warning light will remain
on if a fire has occurred but will go out if a hot gas
leakage is present. If a fire has occurred the warning
light will go out after the fire has been extinguished;
it will also go out if the electrical wiring has burned
through.
MAIN SERVICES
15. Pneumatic system
An engine-driven air compressor charges a bottle to
450 lb./sq.in. maximum for the operation of the wheel
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