PART III-HANDLING
(f) If the fuel pressure indicator shows white (fuel pressure
low) when the belly tank is being used, switch the over-
ride switch to TAKE-OFF immediately.
53. Engine handling
(a) The acceleration control unit (A.C.U.) ensures optimum
acceleration under normal flight conditions at low
altitude but becomes progressively less effective with
increase in height. Except in cases of necessity throttle
AL3/57 movements should be smooth and progressive. Damage to the
engine may result if the throttle is closed too rapidly at high I.A.S.
(b) When the compressor is hot the engine will not accelerate
from low r.p.m., (below about 3,500). These conditions
can only be reached if the throttle is closed after a period
at high or moderate power at low speed (e.g. the
approach to land). At high speed this will not occur as
the r.p.m. will not fall low enough until the speed has
dropped off by which time the compressor will have
cooled. It may be found, particularly in hot weather,
that the engine will not accelerate when the throttle is
opened to taxy away at the end of the landing run. In
this case the throttle should be closed and opened again
to assist the engine to pick up but careful watch must be
kept on j.p.t.
WARNING.-Except in cases of extreme emergency no
attempt should be made to overshoot once
the throttle has been fully closed for landing.
(c) When temperatures at high altitude are below normal a
combination of high r.p.m. and low forward speed can
produce a compressor stall which is accompanied by one
or more loud bangs. With the compressor in a stalled
condition the engine will idle at lower r.p.m. than is
normal at high altitude and a slight buzzing noise may
be discernible, in this condition the engine will not
accelerate when the throttle is opened. If this occurs the
throttle should be closed at once to prevent excessive
j.p.t. and speed increased until the compressor unstalls
and buzzing ceases. Up to 8,000 feet may be lost before
the compressor will unstall and it should not be assumed
that a flame out has occurred unless the r.p.m. are
substantially below 3,000. If flame out has occurred the 48
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