THRUSH AIRCRAFT, INC – MODEL S2R-R1340
AIRCRAFT MAINTENANCE MANUAL
9-2
Effective: 01/01/08
DISPERSAL SYSTEMS
GENERAL DESCRIPTION
A reinforced fiberglass hopper is the
principal part of both the solid and spray
units. The hopper top forms the cowling
from the cockpit forward to the firewall.
The hopper gate box is designed to be
liquid as well as dust tight. Emergency
jettison controls permit the entire liquid
load to be dumped in approximately 7
seconds for the 400 gal. Hoppers.
The dispersal system has been designed
to handle a wide range of dispersal
equipment, and to allow for a quick, easy
changeover from one type of equipment
to another. All dispersal plumbing is
externally mounted and equipped with
quick-disconnects to allow for ease of
maintenance and cleaning. The
streamlined aluminum extrusion spray
booms are located below the wing
trailing edge and utilize the downwash
from the wing to increase penetration
(See Figure 9-4). The booms are fitted
with spraying system diaphragm type
nozzles and normally will use 35 nozzles
for low volume output and 70 nozzles for
high volume output. In addition, the
spray booms have large end plugs that
can be removed to aid in flushing the
system.
The spray pump is located under the
fuselage between the main landing gear
struts. A three-way suck-back spray
valve located at the left, underside of the
fuselage, controls the spray pressure
and flow. The valve is actuated from the
cockpit to obtain the desired operating
pressures for various spray applications.
Spray pressure is indicated by a gauge
mounted on the left boom and is
controlled by a vernier adjustment on the
liquid spray-operating handle. The spray
pump is a wind-driven fan type.
HOPPER
Ref. Figure 9-1
HOPPER CARE
Regardless of the materials used in the
construction or coating of the hopper, it
should be thoroughly washed after each
day’s work. Use cold, clean water and
any domestic detergent. Inspect the
interior of the hopper daily for evidence
of chemical attack, such as surface
roughness or deterioration of the resin.
Look for cracks that may have started in
the areas of highest stress, such as
attach points and stiffener center
portions. Repairs should be made at the
beginning of the problem, rather than
after it has progressed to a serious
degree.
* NOTE *
After washing, it is very
important that the door and
gate be left open for good
ventilation and complete
drying. It is good practice to
rinse the hopper with cold
water after use with
chemicals, even if the idle
period ahead is going to be
only a few hours.
