MIL-S-83318 Sealing Compound, Low Temperature Curing, Quick Repair Integral Fuel Tanks And Fuel Cell Cavities S/S By Sae-Ams-S-83318This specification covers a two component, temperature??resistant ??65??F to +250??F ??54??C to +120??C, low temperature 20??F minimum curing synthetic rubber compounds for quick repair of aircraft integral fuel tanks and fuel cell cavities. During application, the sealing compounds shall be a suitable, fluid consistency.

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MIL-S-83318A(USAF)

4.9.13 Fluid rupture resistance. A 0.125 inch (3 mm) hole shall be drilled in the center of a

0.040 x 3.5 x 3.5 inch (1.00 x 88 x 88 mm) test panel conforming to QQ-A-205/12. A fillet of sealant 0.125 + 0.15 inch (3 mm + 0.4) thick and 0.50 inch (13 mm) in diameter shall be applied to the center of the panel covering the hole. After curing 1 hour at standard conditions, a 0.50 inch (13 mm) cork borer shall be used to trim excess sealant and the panel shall be installed in apparatus as shown in figure 4. This apparatus consist of a glass bulb fitted with a buna-N-o-ring. After installation of the panel, 100 millimeters of jet reference fluid shall be added to the apparatus, the plastic tubing attached, and 10 psig air pressure applied to the top of the fluid. This pressure shall be maintained for 24 hours at standard conditions.

4.9.14 Tensile strength and elongation . Mixed sealing compound 0.125 +0.015 inch (3.0

+0.4 mm) thick shall be prepared by pressing between 2 polyethylene sheets, removing the top sheet at the end of the tack-free time and allowing the sealing compound to cure as specified in 4.7.6. Nine tensile test specimens shall be cut from the sheet using die C, as specified in ASTM 0412. Three specimens shall be exposed to each of the environmental conditions specified table II. Where fluid immersion is specified, the specimens shall be immersed in 400 ml of the jet reference fluid. Specimens to be tested after the fluid immersion shall be cooled for 24 hours at 77°F (25°C) and tested within 5 minutes after removal from the fluid. Specimens to be tested after oven aging shall be allowed to cool for

16 to 48 hours at standard conditions before testing. The tensile and elongation tests shall be conducted at a standard conditions in accordance with ASTM 0412 at a jaw separation rate of 20 inch + 1 (508 mm +25) per minute.

4.9.15 Low-temperature flexibility. Four test panels 0.040 by 2.75 by 6 inch (1.00 by 70 by

150 mm) in size shall be prepared from aluminum alloy conforming to temper T6 of

QQ-A-250/13. A coating of the sealing compound 00.1 x 1.5 x 4 inch (2.5 x 40 x 100 mm) thick shall be applied to the center of each of the 4 panels. Care shall be taken to maintain an accurate sample thickness of 0.1 inch (2.5 mm). At the end of a standard cure, as specified in 4.7.6, two of the specimens shall be immersed in 900 ml of jet reference fluid for

7 days at 250°F (121°C).. All four panels shall then be immediately placed in a

low-temperature flexibility fixture as shown in figure 5, consisting of a clamp support that will grip both sides of both 6-inch (150 mm) edges of the panel for a distance of 3 inch (75 mm) from one end without touching the sealant as shown in figure 5.. The fixture shall be capable of flexing the panel through a 30 degree arc (15 degrees each side of the center) at a constant speed of 1 cycle per 5 seconds. The temperature shall be reduced to -65°F (54°C), stabilized at this temperature for 2 hours, and the panels flexed through 130 consecutive cycles .