King Air C90GTi, Pilot Training Manual

Page: 184 / 557

FUEL TOPPING GOVERNOR
The fuel topping gover nor can also control
an overspeed condition and is set at 6% above
the primar y gover nor’s selected speed. In
an over-speed condition, the fuel topping
g ove r n o r w i l l l i m i t p r o p e l l e r r p m by d e -
creasing pneumatic pressure to the fuel con-
trol unit, reducing fuel flow and engine speed
as means of controlling propeller r pm. In
reverse, the fuel topping governor is reset to
95% of selected r pm to insure that the pro-
peller will not reach the selected r pm. The
fuel topping gover nor will only prevent an
over-speed if the primar y gover nor’s fly-
weight’s are still operational.
POWER LEVERS
The power levers (Figure 7-35) are located
on the power lever quadrant (f irst two levers
on the left side) on the center pedestal. They
are mechanically interconnected through a
cam box to the fuel control unit, the Beta
valve and follow-up mechanism, and the fuel
t o p p i n g ( N P ) g ove r n o r. T h e p owe r l eve r
quadrant per mits movement of the power
lever from idle to maximum thr ust and in
the Ground Fine and Reverse ranges from
idle to maximum reverse. Two gates in the
power lever quadrant aft of the IDLE posi-
tion, prevent inadver tent movement of the
power lever into the GROUND FINE or RE-
VERSE ranges. The pilot must lift the power
levers up and over the f irst gate to select
GROUND FINE, and up and over the sec-
ond gate to select REVERSE.
The function of the power levers is to es-
tablish a gas generator r pm through the gas
g e n e r a t o r g ove r n o r ( N
G
) a n d a f u e l f l ow
that will produce and maintain the selected
N
1
r p m . I n t h e B e t a o r G RO U N D F I N E
range, the power levers are used to change
t h e p r o p e l l e r bl a d e a n g l e , t h u s c h a n g i n g
propeller thr ust.
In the REVERSE range, the power lever:
• Selects a blade angle propor tionate to
the aft travel of the lever
• Selects an N
1
that will sustain the se-
lected reverse power
• Resets the fuel topping governor from
i t s n o r m a l s e t t i n g o f 1 0 6 % t o
a p p r ox i m a t e ly 9 5 % o f t h e p r i m a r y
gover nor setting
KING AIR C90GTi/C90GTx PILOT TRAINING MANUAL
7-39
FOR TRAINING PURPOSES ONLY
7
POWERPLANT
FORWARD
FINE
PITCH
GROUND LOW PITCH STOP POWER LEVER
TOP OF
REVERSE
RANGE
MARKS
MAXIMUM
REVERSE
Figure 7-35. Power Levers