Dispersal Systems; General Description; Hopper; Hopper Care - Thrush Aircraft S2RHG-T65 TURBO THRUSH Maintenance Manual

Table of Contents

THRUSH AIRCRAFT, INC – MODEL S2RHG-T65 TURBO THRUSH

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 550 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 9-6).

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.

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

may then be made at the beginning of the problem, rather than after it has progressed to

a serious degree.

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.

9-2

AIRCRAFT MAINTENANCE MANUAL