What are the three sealant categories?

What are the three sealant categories?

• A. Pliable sealants (pressurisation); Drying sealants (pressurisation); Curing sealants (fuel)
• B. Hard sealants; Soft sealants; Flexible sealants
• C. Structural sealants; Decorative sealants; Lubricating sealants
• D. Thermal sealants; Electrical sealants; Magnetic sealants

Answer: (A)

The main idea is that sealants in aviation are grouped by how they cure and how they behave after curing, which determines where they’re best used. Pliable sealants are designed to stay flexible after they cure, so they can absorb vibration and the thermal movement of joints in pressurized areas without cracking or losing seal integrity. Drying sealants set by solvent evaporation, forming a film without extensive chemical crosslinking, which makes them useful where a faster cure is helpful and solvent loss is acceptable. Curing sealants cure chemically (or with moisture) and typically develop strong resistance to fuels and solvents, making them ideal for areas exposed to fuel or where a very robust seal is required. The other groupings don’t fit because they focus on how hard or soft the film is, or on the broad function or environment rather than the cure mechanism. Hard/soft/flexible describes mechanical properties, not how the sealant cures. Structural/decorative/lubricating describes use cases rather than cure behavior. Thermal/electrical/magnetic describes performance once in place, not the curing process.

The main idea is that sealants in aviation are grouped by how they cure and how they behave after curing, which determines where they’re best used. Pliable sealants are designed to stay flexible after they cure, so they can absorb vibration and the thermal movement of joints in pressurized areas without cracking or losing seal integrity. Drying sealants set by solvent evaporation, forming a film without extensive chemical crosslinking, which makes them useful where a faster cure is helpful and solvent loss is acceptable. Curing sealants cure chemically (or with moisture) and typically develop strong resistance to fuels and solvents, making them ideal for areas exposed to fuel or where a very robust seal is required.

The other groupings don’t fit because they focus on how hard or soft the film is, or on the broad function or environment rather than the cure mechanism. Hard/soft/flexible describes mechanical properties, not how the sealant cures. Structural/decorative/lubricating describes use cases rather than cure behavior. Thermal/electrical/magnetic describes performance once in place, not the curing process.