Fuel Line Maintenance; Sealing Compounds - Thrush Aircraft S2RHG-T65 TURBO THRUSH Maintenance Manual

Table of Contents

THRUSH AIRCRAFT INC – MODEL S2RHG-T34 TURBO THRUSH

CS 3204 A2 sealer may be used as a thread lubricant or to seal minor connection leaks

throughout the fuel system. Apply sparingly to male fittings only. Make sure that a

sealing compound or residue from a previously used compound, or any other foreign

matter does not enter the fuel system.

Protect all drain openings and fuel outlet screens when

applying sealant.

Any repair that breaks the fuel tank seal will necessitate resealing of that area of the tank.

Repair parts that need sealing must be installed and riveted during the sealing operation.

CS 3204 A2 or B2 sealant meets AMS-S-8802 (formerly Mil-S-8802) standards. It is a

fuel resistant sealant use on integral "wet wing" fuel tanks as well as other areas subject

to contact with aircraft fuels, lubricants, oils, agriculture chemicals, water and/or

weathering. Thrush Aircraft Inc uses two grades; CS 3204 A2 which is thin, brushable,

and self leveling liquid and CS 3204 B2 which is a thixotropic paste that will not flow or

sag on overhead or vertical surfaces. Thrush Aircraft Inc recommends the use of

"Semkit®," which are easy-to-use pre-measured 6 oz. Plastic tubes with a 4.5 oz. Fill of

product. When mixing materials packaged in bulk or when only a small quantity is

required, stir 10 parts by weight of the part "B" component into 100 parts by weight of the

part "A" component. Mix and stir both components until a uniform gray color is achieved.

There should be no white or black streaks in the properly blended material. Blend the

components slowly, as violent stirring will entrap air in the cured sealant. Do not thin CS

3204 with solvents. Thoroughly clean all surfaces to which CS 3204 is to be applied

immediately prior to sealant application. Cleaning shall be accomplished with clean lint-

free paper or cloth towels or small paintbrushes soaked with Acetone or Methyl Ethyl

Ketone and wiped clean. Always clean an area longer and wider than the width of the

finally applied sealant to insure maximum bonding. CS 3204 is also used to make and

seal all exposed stressed skin joints and overlap fillets, fiberglass to aluminum overlap

fillets and seal cockpit windows to prevent water and agriculture chemical entry into these

vital structures. CS 3204 is used to seal all bolts in hold-down and carry-through duty in

the chemical hopper. CS 3204 can be painted when cured. Alternate sealers for CS

3204 class A & B are PR-1422 class A & B and PR-1750 class A & B. For fast set up

times (20 minutes application life and cure time) "Quick Set" CS-3204 B1/4 or PR-1435

may be used as an alternate sealer anywhere on the aircraft. CS 3600 (Mil-S-4383C) is

used by Thrush Aircraft as a topcoat for all the above listed polysulfide sealers inside of

the Thrush's integral fuel tanks. It is one part (no mixing), has the consistency of thin

syrup and can be painted on top of all previously sealed internal fuel tank seams. If CS

3600 is used, it must be allowed to air dry for 4 days minimum before being exposed to

fuel. "Semkit®" pre-measured cartridges can best be applied by use of either a Semco®

model 250 pneumatic or model 850 hand operated application gun. The Thrush Aircraft

factory uses the following nozzles: Semco® model Nos. 252 (2.5", 1/16" orifice), 410 (4",

1/32" orifice), or 440 (4", 1/8" orifice). The plastic nozzle tip can be cut with a razor knife

to enlarge or modify the tips orifice size and shape to control the size and shape of the

material bead.

5-8

AIRCRAFT MAINTENANCE MANUAL