King Air C90GTi, Pilot Training Manual

Page: 198 / 557

The system consists of the following: three
p h o t o c o n d u c t ive c e l l s f o r e a c h e n g i n e ; a
control amplif ier for each engine; two red
war ning lights on the war ning annunciator
panel, one L ENG FIRE and the other R ENG
FIRE, along with a red FIRE annunciator
located in each ITT/Torque engine display;
a test switch on the copilot’s left subpanel;
and a circuit breaker placarded FIRE DET
on the right side panel.
T h e s i x p h o t o c o n d u c t iv e - c e l l f l a m e d e -
tectors are sensitive to infrared radiation.
They are positioned in each engine com-
par tment so as to receive both direct and
r e f l e c t e d i n f r a r e d r ay s , t h u s m o n i t o r i n g
t h e e n t i r e c o m p a r t m e n t w i t h o n ly t h r e e
photocells. Temperature level and rate of
t e m p e r a t u r e r i s e a r e n o t c o n t r o l l i n g f a c -
tors in the sensing method.
Conductivity through the photocell varies
in direct propor tion to the intensity of the
infrared radiation striking the cell. As con-
ductivity increases, the amount of cur rent
from the electrical system flowing through
the flame detector increases proportionally.
To prevent stray light rays from signaling a
false alar m, a relay in the control amplif ier
closes only when the signal strength reaches
a preset alar m level. When the relay closes,
t h e a p p r o p r i a t e l e f t o r r i g h t wa r n i n g a n -
n u n c i a t o r s i l l u m i n a t e . W h e n t h e f i r e h a s
been extinguished, the cell output voltage
drops below the alar m level and the relay in
the control amplif ier opens. No manual re-
setting is required to reactivate the f ire de-
tection system.
FIRE DETECTION TEST
SYSTEM
The rotar y switch on the copilot’s left sub-
panel, placarded TEST SWITCH-FIRE DET,
has four positions: OFF–3–2–1. (If the op-
tional engine f ire extinguishing system is
i n s t a l l e d, t h e s w i t c h i s p l a c a r d e d T E S T
SWITCH–FIRE DET & FIRE EXT and the
l e f t s i d e o f t h e t e s t s w i t c h w i l l i n c l u d e
LEFT–EXT–RIGHT positions.)
The three test positions for the f ire detector
system are located on the right side of the
switch. When the switch is rotated from OFF
(down) to any one of these three positions, the
output voltage of a corresponding flame de-
t e c t o r i n e a c h e n g i n e c o m p a r t m e n t i s
increased to a level suff icient to signal the
amplif ier that a f ire is present.
The following should illuminate as the se-
lector is rotated through each of the three
positions: the MASTER WARNING flasher,
the L ENG FIRE and R ENG FIRE war ning
annunciators and, if the optional engine f ire
extinguishing system is installed, the red
lenses placarded L ENG FIRE EXT–PUSH
and R ENG FIRE EXT–PUSH on the f ire-
extinguisher activation switches. The sys-
t e m m ay b e t e s t e d a ny t i m e , e i t h e r o n t h e
g r o u n d o r i n f l i g h t . T h e T E S T S W I T C H
should be placed in all three positions, in
order to verify that the circuitr y for all six
f i r e d e t e c t o r s i s f u n c t i o n a l . I l l u m i n a t i o n
failure of all the f ire detection system an-
nunciators when the TEST SWITCH is in
any one of the three flame-detector-test po-
s i t i o n s i n d i c a t e s a m a l f u n c t i o n i n o n e o r
both of the two detector circuits (one in each
engine) being tested by that par ticular po-
sition of the TEST SWITCH.
FIRE EXTINGUISHING
SYSTEM
The optional engine f ire extinguishing sys-
tem (Figure 8-2) incor porates an explosive
cartridge inside the extinguisher of each en-
gine. Each engine has its own self-contained
extinguishing system, which can be used
only once between rechargings. This sys-
tem cannot be crossfed. When the activa-
t i o n v a l v e i s o p e n e d, t h e p r e s s u r i z e d
extinguishing agent is discharged through a
p l u m b i n g n e t wo r k w h i c h t e r m i n a t e s i n
strategically located spray nozzles.
The f ire extinguisher control switches used
to activate the system are located on either
side of the annunciator panel. Their power
KING AIR C90GTi/C90GTx PILOT TRAINING MANUAL
8-3
FOR TRAINING PURPOSES ONLY
8
FIRE
PRO
TECTION