King Air C90GTi, Pilot Training Manual

Page: 127 / 557

T h e o t h e r s o u r c e o f p owe r t o t h e b o o s t
pumps is directly from the batter y through
t h e b a t t e r y e m e rg e n cy b u s . D u r i n g s h u t -
down, both boost pump switches and cross-
feed must be turned off to prevent discharge
of the batter y.
FIREWALL SHUTOFF VALVES
Th e f irewall s h u to ff valves (Fig u re 5 -7 ),
l o c a t e d b e t we e n t h e e n g i n e - d r i v e n f u e l
pump and the nacelle tank, are controlled by
guarded switches in the cockpit (Figure 5-
8). There is one switch on each side of the
fuel system circuit breaker panel on the fuel
panel. These switches have two positions.
The OPEN position allows uninter r upted
fuel flow to the engine. The CLOSE posi-
tion cuts off all fuel to the engine. When
the red guard closes, it forces the switch
into the open position and protects it in the
open position.
Each f irewall shutoff valve receives elec-
tric power through its own 5-amp breaker
on the fuel panel which brings electric power
from the triple-fed bus as well as the gen-
erator bus. This source of power is available
o n l y w h e n t h e b a t t e r y a n d / o r g e n e r a t o r
switches are on. The only pilot action nec-
essary to ensure main fuel system operation
is to have the f irewall shutoff valves in the
OPEN position.
CROSSFEED OPERATION
Crossfeeding fuel is authorized only in the
eve n t o f e n g i n e f a i l u r e o r e l e c t r i c b o o s t
p u m p f a i l u r e .
Each nacelle tank is connected to the engine
i n t h e o p p o s i t e w i n g by a c r o s s f e e d l i n e
routed from the side of the nacelle, aft to
the center section, and across to the side of
the opposite nacelle. The crossfeed line is
controlled by a valve (Figure 5-9). With the
crossfeed valve OPEN, one system can sup-
ply fuel to the other engine. The system uses
the electric boost pump in the nacelle tank.
This pump supplies the pressure to transfer
fuel as well as fuel boost to one or both en-
g i n e s . Wi t h o n e e n g i n e i n o p e r a t iv e , t h e
crossfeed system allows fuel from the in-
o p e r a t i v e s i d e t o b e s u p p l i e d t o t h e
operating engine.
KING AIR C90GTi/C90GTx PILOT TRAINING MANUAL
5-10
FOR TRAINING PURPOSES ONLY
5
FUEL
SY
STEM
VALVE
Figure 5-7. Firewall Shutoff Valve
Figure 5-8. Firewall Shutoff Valve
Switches