King Air C90GTi, Руководство по подготовке пилотов

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FUEL HANDLING
PRACTICES
Takeoff is prohibited when the fuel-quan-
tity indicator needles are in the yellow arc,
with the selector in the total position, or
when there is less than 265 pounds of fuel
in each wing system.
Both boost pumps must be operable prior to
takeoff.
A l l hy d r o c a r b o n f u e l s c o n t a i n s o m e d i s -
solved and some suspended water. The quan-
tity of water contained in the fuel depends
o n t e m p e r a t u r e a n d t h e t y p e o f f u e l .
Kerosene, with its higher aromatic content,
tends to absorb and suspend more water than
aviation gasoline. In addition to water, it
will suspend rust, lint and other foreign ma-
terials longer. Given suff icient time, these
suspended contaminants will settle to the
bottom of the tank.
The settling time for kerosene is f ive times
that of aviation gasoline; therefore, jet fuels
require good fuel-handling practices to as-
sure that the air plane is ser viced with clean
fuel. If recommended g round procedures
are carefully followed, solid contaminants
will settle and free water can be reduced to
30 par ts per million (ppm), a value that is
cur rently accepted by the major airlines.
Since most suspended matter can be removed
from the fuel by suff icient settling time and
proper f iltration, it is not a major problem.
Dissolved water has been found to be the
major fuel contamination problem. Its ef-
fects are multiplied in aircraft operating pri-
marily in humid regions and warm climates.
Dissolved water cannot be f iltered from the
fuel by micronic-type f ilters, but can be re-
l e a s e d by l owe r i n g t h e f u e l t e m p e r a t u r e ,
which will occur in flight. For example, a
kerosene fuel may contain 65 ppm (8 fluid
ounces per 1000 gallons) of dissolved water
at 80°F. When the fuel temperature is low-
ered to 15°F, only about 25 ppm will remain
in solution. The difference of 40 ppm will
h ave b e e n r e l e a s e d a s s u p e r c o o l e d wa t e r
droplets which need only a piece of solid
contaminant or an impact shock to conver t
them to ice cr ystals.
Tests indicate that these water droplets will
not settle during flight and are pumped freely
through the system. If they become ice crys-
tals in the tank, they will not settle since the
specif ic gravity of ice is approximately equal
to that of kerosene. The 40 ppm of suspended
water seems like a ver y small quantity, but
when added to suspended water in the fuel
at the time of deliver y, it is suff icient to ice
a f ilter. While the critical fuel temperature
range is from 0 to -20°F, which produces se-
vere system icing, water droplets can freeze
at any temperature below 32°F.
KING AIR C90GTi/C90GTx PILOT TRAINING MANUAL
5-15
FOR TRAINING PURPOSES ONLY
5
FUEL
SY
STEM
NUMBER DRAINS LOCATION
1 Leading Edge Tank Sump On underside of outboard wing, just forward of main spar
1 Firewall Fuel Filter (Strainer) Drain Flush drain valve is accessible on underside of engine cowling
1 Boost Pump Sump Bottom center of nacelle, forward of wheel well
1 Transfer Pump Sump Drain Just outboard of wing root, forward of flap
1 Wheel Well Sump Inside wheel well on gravity feed line
Figure 5-14. Fuel Drain Locations