PR-2870 Class C-48 is a non-chromate corrosion inhibitive
fay surface sealant. It has a service temperature range from
-80°F (-62°C) to 250°F (121°C), with intermittent excursions up
to 300°F (149°C). This material acts as an effective corrosion
inhibitor when used with aluminum alloys or with dissimilar
metals. The cured sealant maintains elastomeric properties
after limited exposure to both jet fuel and aviation gas.
PR-2870 Class C-48 is a two-part, epoxy cured PERMAPOL®
P-3.1 polythioether compound. The uncured material is a
roller-grade liquid suitable for application by brush, extrusion
gun or spatula. It cures at room temperature to form a
resilient sealant having excellent adhesion to common aircraft
substrates.
The following tests are in accordance with
MIL-PRF-81733 Type IV, Class 2, Grade B test methods
Surface Preparation:
Immediately before applying sealant to primed
substrates, the surfaces should be cleaned with solvents.
Contaminants such as dirt, grease, and/or processing
lubricants must be removed prior to sealant application.
A progressive cleaning procedure should be employed using
appropriate solvents and a new lint-free cloth conforming to
AMS 3819. (Reclaimed solvents or tissue paper should not be
used.) Always pour solvent on the cloth to avoid contaminating
the solvent supply. Wash one small area at a time.
It is important that the surface is dried with a second
clean cloth prior to the solvent evaporating to prevent the
redeposition of contaminants on the substrate.
Substrate composition can vary greatly. This can affect sealant
adhesion. It is recommended that adhesion characteristics
to a specific substrate be determined prior to application on
production parts or assemblies.
For a more thorough discussion of proper surface preparation,
please consult the SAE Aerospace Information Report
AIR 4069. This document is available through SAE, 400
