Aircraft Sealants and Adhesives for MRO Applications
Classes, cure schedules, pot life and pack forms — what to specify when you order aircraft sealants and adhesives so the shop can actually use them.
Sealants and adhesives are process materials. The product is only half the order — the class, the pack form and the remaining application life decide whether the task card can be completed.
Sealant families
Aircraft sealants are grouped by the job they do:
- Integral fuel tank sealants, resistant to fuel and used inside wet wing structure
- Aerodynamic smoothing and fillet sealants for external surfaces
- Corrosion inhibiting sealants for faying surfaces and fastener installation
- Firewall and high temperature sealants
- Windshield, window and canopy sealants
- Electrical potting and encapsulating compounds
Class and application life
Most sealants come in classes: brush grade for thin coatings, fay surface grade for assembly, fillet grade for beads, and extrusion grade for guns. Each class also carries an application life — the working time after mixing before the material becomes unusable. Order the class the task card calls for, and check the application life against how long the job actually takes: a two-hour job cannot be done with a half-hour sealant.
Pack forms and cold chain
Sealants are supplied as base-and-accelerator kits to be mixed on the bench, as semkits mixed in their own container, or as pre-mixed frozen cartridges. Frozen cartridges save shop time but need cold chain handling in transit and a freezer on arrival; if you have no freezer, order kits instead. State what you have before the order is placed, not after the shipment lands.
Structural and general adhesives
Adhesives split broadly into structural systems — film and paste adhesives, two-part epoxies — and general workshop products such as threadlockers, cyanoacrylates and contact adhesives. Structural bonding is a system: adhesive, primer or adhesion promoter, cleaning solvent and a defined surface preparation. Order the whole system together; a bond made with the right adhesive and the wrong primer is still a bad bond.
Cure, mix ratio and surface preparation
Follow the manufacturer's mix ratio by weight where one is published, respect induction time, and cure at the specified temperature. Surface preparation is where most bond failures begin: contamination, moisture and the wrong abrasive undo an otherwise perfect process. Keep the Technical Data Sheet with the material so the mechanic works from the manufacturer's numbers rather than memory.
Shelf life, storage and documentation
Both sealants and adhesives are shelf-life controlled. Store within the temperature range on the label, record batch numbers on receipt, and reject anything whose remaining life will not cover your planned use. Certificates of Conformity, Certificates of Analysis, MSDS and Technical Data Sheets should be requested at quotation stage so they match the batch supplied.
Frequently asked questions
- What is the difference between sealant classes?
- Class describes consistency and application method — brush, fay surface, fillet or extrusion grade — and each class has its own application life.
- Can pre-mixed frozen cartridges be shipped internationally?
- Yes, with cold chain packing agreed before despatch. Where cold chain is not practical we supply kits to be mixed on site instead.
Need a price for a part number?
Send the part number, quantity and required condition — routine enquiries are answered within one business day, AOG immediately.
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