King Air C90GTi, Pilot Training Manual

Page: 128 / 557

T h e c r o s s f e e d s y s t e m i s c o n t r o l l e d by a
three-position switch placarded: CROSS-
F E E D O P E N, AU TO, a n d C L O S E D. T h e
valve can be manually opened or closed, but
under nor mal flight conditions it is left in
the AUTO position. In the AUTO position,
the fuel pressure switches are connected into
the crossfeed control circuit.
In the event of a boost pump failure, causing
a drop in fuel pressure, these switches open the
crossfeed valve allowing the remaining boost
pump to supply fuel to both engines.
In the event of a boost pump failure during
takeoff, the system will begin to crossfeed
automatically allowing the pilot to complete
the takeoff without an increase in workload
at a cr ucial time. After the takeoff is com-
pleted, or if the boost pump fails after take-
off, the crossfeed switch may be closed and
the flight continued relying on the engine-
driven high pressure pump without boosted
pressure. In some instances, the pilot may
e l e c t t o c o n t i n u e t h e f l i g h t w i t h t h e r e -
maining boost pump and the crossfeed sys-
tem in operation.
When the crossfeed switch on the fuel con-
trol panel is actuated, power is drawn from
a 5-ampere circuit breaker on the fuel con-
t r o l p a n e l t o t h e s o l e n o i d t h a t o p e n s t h e
c r o s s f e e d v a l v e . T h e c r o s s f e e d i s a l s o
p o w e r e d t h r o u g h t h e h o t b a t t e r y b u s
t h r o u g h a 5 - a m p f u s e .
W h e n t h e c r o s s f e e d v a l v e i s r e c e i v i n g
power, the yellow FUEL CROSSFEED light
on the annunciator panel will illuminate.
The crossfeed will not transfer fuel from
one wing to another; its function is to sup-
ply fuel from one side to the opposite engine
during a boost pump failure or an engine-
out condition. If the boost pumps on both
sides are operating and the crossfeed valve
is open, fuel will be supplied to the engines
in the nor mal manner because the pressure
on each side of the crossfeed valve should
be equal.
KING AIR C90GTi/C90GTx PILOT TRAINING MANUAL
5-11
FOR TRAINING PURPOSES ONLY
5
FUEL
SY
STEM
L
L
HIGH PRESSURE
CROSSFEED
LEGEND
Figure 5-9. Crossfeed Schematic