PART III - HANDLING
tial, the test should be carried out as often as possible
as a check of serviceability and to ensure against the
system becoming sluggish.
(ii) With the parking brakes on, open up to 80 per cent.
r.p.m. and move the emergency fuel system switch to
ON. Open the throttle slowly and carefully to fully open
and check that the r.p.m. do not exceed 100 per cent. to
101 per cent. If the r.p.m. reach 101 per cent. before
the throttle is fully open the emergency fuel system is
unserviceable and the aircraft should not be flown.
(iii)While still at full throttle move the emergency fuel system
switch to TEST. The r.p.m. will fall to about 96 per
cent. r.p.m. on a normal day, about 91 per cent. on a
cold day and to 99 per cent. on a hot day. The initial
drop may be rather more than these figures but the
recovery time from the moment of selecting TEST to
stabilizing must not exceed 3-4 seconds. If it does, the
emergency fuel system is unserviceable. Repeated tests
of a serviceable emergency fuel system during the same
run-up should not differ by more than 1 per cent.
(iv) Finally, move the emergency fuel system switch to ON.
The r.p.m. should then return to the original full throttle
figure. If it is intended to use the emergency system
during take-off as a safeguard, leave the switch on, release
the brakes and commence the take-off. Otherwise the
switch should be returned to OFF before releasing the
brakes.
NOTE:-(a) If it is necessary to throttle back to less than
80 per cent. (either before or after take-off)
switch the emergency fuel system OFF
before opening up again. This is to ensure
that the emergency system does not over-
ride the main system during the early part
of the acceleration period causing com-
pressor stall and possible flame extinction.
(b) If an unserviceable emergency fuel system
results in overspeeding, the throttle must be
closed to prevent possible damage. If the
r.p.m. exceeds 104 per cent. irrespective of
j.p.t. the engine must be stopped, and will
have to be removed for overhaul.
56. Take-off
(i) Align the aircraft on the runway and where possible
test the emergency fuel system.
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