General Description - Thrush Aircraft S2R–T660 Maintenance Manual

THRUSH AIRCRAFT INC - T660 TURBO THRUSH
AIRCRAFT MAINTENANCE MANUAL
DISPERSAL SYSTEMS
SECTION NINE

GENERAL DESCRIPTION

A 660 gallon 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 8.4 seconds for the 660 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. 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 upper instrument panel
and is controlled by a vernier adjustment on the liquid spray-operating handle. The spray pump is a
wind-driven fan type, and is controlled from the cockpit by means of a cable to adjust the fan blade
pitch to increase or decrease pump pressure.
9 - 2
Effective: 12/17/03