MIL-S-83318A(USAF)
4.9.16 Hydrolytic stability. A cured specimen of approximately 0.50 inch thick by 3 inch (12 by 7.5 cm) in diameter, shall be exposed for 120 days +4 hours in an environment of 160°F (70°C) and 95% +5 relative humidity. To do this, pour a 22% by weight glycerin in distilled water solution into a desiccator until the liquid level is 1 inch (25 mm) below the desiccator plate. Suspend the sealant specimen in the desiccator so that it does not touch anything. Apply vacuum grease to the lid and slide the lid in place. Loosely stopper the hole to
prevent vacuum build up. Place the desiccator in a circulating air oven set at 160°F (70°C). When the temperature inside the desiccator reaches 160°F (70°C) tightly stopper the hole
to prevent water evaporation. Change the glycerin solution every 30 days or when it becomes cloudy. After 120 days+4 hour remove the desiccator from the oven and allow to cool frequently loosening the stopper. Remove the specimen from the desiccator and hold it at standard conditions for 14 days. The instantaneous hardness shall be determine in
accordance with ASTM D 2240 and reported.
4.9.17 Corrosion. Two aluminum panel conforming to QQ-A250/12 and measuring 0.040 by 2.75 by 6 inch (1.00 by 70 by 150 mm) in size shall be prepared as follows: A controlled area one inch wide by 5 inch long (25 x 125 mm) shall be masked in the center on one side of each panel and the remainder of the panel shall be chemical filmed in accordance with MIL-C-5541 followed by a corrosion protective coating MIL-C-27725. After the coating has cured, the adhesion promoter shall be applied and a 0.062 in (1.5 mm) thick layer of sealing compound shall be applied to the area, overlapping a minimum of 0.25 inch (6 mm) onto the coated protection. The sealant shall be given a standard cure and the panels conditions as follows: The panels shall be immersed vertically for 20 days in a covered glass vessel containing a 2-layer liquid consisting of 3 percent aqueous sodium chloride solution and jet reference fluid so that two inch (50 mm) of the panel is exposed to the salt solution, two
inch (50 mm) is exposed to the jet reference fluid, and the remainder of the panel is exposed to the air-vapor mixture. The temperature of the fluid during the test shall be maintained at 140°F (60°C).
4.8.18 Repairability. Prepare sufficient number of QQ-A-250/13, of Aluminum-alloy peel panels measuring 0.40 x 2.75 x 6 inch (1 x 70 x 150 mm) so that there are 2 panels for each sealing compound already qualified to this specification, plus 2 panels for the material being qualified and 4 panels for material qualified to MIL-S-8802 (2 for type I and 2 for type II). Apply adhesion promoter as specified in 4.7.4 and overcoat one side of the panels with
0.125 inch +0.016 ( 3 mm + 0.5) of sealing compound so that 2 panels are coated with each class B-2 sealing compound already qualified to this specification. 4 panels are
coated with sealing compound qualified to MIL-S-8802 (2 for type I and 2 for type II). and
2 panels are coated with the sealing compound being qualified.After a standard cure as specified in 4.7.6 exposed 1 panel of each sealing compound to jet reference fluid for 3 days at 140°F (60°C) followed by 3 days air drying at 120°F (50°C) then 7 days air aging at
250°F (121°C). Clean all panels as specified in 4.7.3, apply adhesion promoter as specified in 4.7.4 and apply a thickness of 0.125 +0.016 inch (3 +0.5 mm) of newly mixed sealing
compound being qualified over the existing compound. A peel strength panel shall then be prepared in accordance with the method specified in 4.9.9 After a standard cure as specified in 4.7.6 the specimens shall be tested as specified in 4.9.9.
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