AIR TRACTOR AT-502A, Maintenance Section

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Air Tractor, Inc. Maintenance Page 49
AT-502A/502B/504 March 14, 2018
SPRAY PLUMBING
The plumbing from the hopper gate box to the spray pump consists of a p/n 80385-1 tube assembly
with a p/n 22899 coupler attached to the gate box and a 80376-1 hose attached to the 80385-1 tube. The
hose is clamped with 200-56S clamps which are entirely stainless.
The plumbing from the discharge side of the pump to the valve is p/n 80177-1 and has a 80743-1
coupler at the valve end. The hoses are p/n 80045-1 and are double clamped with QS200M36S clamps. In
addition, at the pump an 81069-1 strap is used to safety the clamp to the top of the pump quick coupler (p/n
42320) to prevent the 80177-1 tube from blowing off due to high pressure and water hammer effects.
The tube attaching to the strainer is p/n 80765-
1 and the boom “Tee” assembly is p/n 80392-12.
Standard spray booms are p/n 80307-1 and will fit on either side. Micronair booms are p/n 80333-1 (L/H) and
80333-2 (R/H).
The boom “Tee” assembly is supported on the L/H side with a p/n 80400-4 assembly and on the R/H
side with a p/n 80386-4 assembly. The straps on the support assemblies are p/n 80383-1 and are attached
with AN4C6A bolts. D4-10T-303 Faspins are used to attach the support assemblies to the fuselage frame.
BOTTOM LOAD PLUMBING
The bottom load valve is a Transland 20395 which has shims that can be removed when wear
develops.
The aft half of the bottom loading plumbing is p/n 80328-1 and attaches to the bottom loading valve
with a 80045-1 hose and to the control valve with a 80046-1 hose and two QS200M28S clamps.
The forward half of the bottom loading plumbing is a 80239-1 tube assembly.
The valve handle should be positioned straight back when the valve is closed. The valve is attached to
the L/H support assembly with four AN4-4A bolts. A Transland 85053 adapter is attached to the bottom load
valve.
SPRAY NOZZLES
Forty-one spray nozzles are standard. These are Spraying Systems Inc. p/n 4666 diaphragm check
valve, p/n 1/8 Q JJ body, and p/n QU-4010 spray tip. A variety of orifice sizes are available in the Quick Vee
Jet spray tips. The aircraft is equipped at the factory for medium volume applications. For high volume
spraying an additional 40 nozzles should be installed. Remove the p/n 3151 x 2 plugs and install p/n 3325x2
hex nipples for the extra nozzles. Be sure to apply Rector Seal or equivalent to the threads of the hex nipples
during installation.