SEALING COMPOUNDS

SEALING COMPOUNDS

Preventing Leaks & Corrosion

PREVENTING LEAKS & CORROSION

Certain areas of aircraft are sealed to:

Preventing Fuel Leakage

Withstand Pressurization

Preventing Corrosion

Block Fumes

Most sealants consist of two or more ingredients properly proportioned and compounded. Some are ready for use as packaged, while others requiremixing before application.​

TYPES OF SEALING COMPOUNDS

One-Part Sealants

Prepared by the manufacturer and ready for application as packaged. The consistency may be altered to suit a particular application method using the manufacturer-recommended thinner.​

Two-Part Sealants

Require separate packaging toprevent cure prior to application:​

• Base sealing compound
• Accelerator

Any alteration of the prescribed ratiosreduces the quality of the material.Typically combined by equal portions,by weight, of base compound andaccelerator.​

TWO-PART SEALANT APPLICATION PROCESS

The curing rate varies with temperature and humidity. Ideal conditions are 77°F with 50% relative humidity for most sealants.​

Preparation

Weighing

Mixing

Application

Testing

SEALANT CURING CONSIDERATIONS

Temperature Effects

• Curing is extremely slow below 60°F
• Heat can accelerate curing, but should never exceed 120°F
• Heat sources include infrared lamps or filtered heated air

Application Guidelines

• Heat should not be applied to the fraying surface sealant until all work is completed
• All attachments must be completed within the application limitations of the sealant
• Sealant must be cured to a tack-free condition before applying brush top coatings

Tack-free consistency is reached when a sheet of cellophane pressed onto the sealant no longer adheres.