H.B. Fuller EY3804B (1-USPT-CAN)

EY3804 Composite Repair & Structural Adhesive

Overview

EY3804 is a low-viscosity, two-component epoxy structural adhesive developed for permanent composite repairs in aerospace applications. It offers room-temperature or elevated-temperature curing, excellent high-temperature mechanical performance and outstanding resistance to hot water immersion. Designed for field repair of composite structures, EY3804 delivers high-strength bonds to composites, metals, coatings and most engineering plastics while meeting demanding aerospace repair specifications.

Key Technical Specs

• Product Type: Two-component epoxy structural adhesive
• Technology: Epoxy
• Appearance: Dark Grey (mixed)
• Consistency: Low-viscosity liquid
• Mix Ratio (by weight): Part A 100 : Part B 66
• Mixed Viscosity: Approximately 3,900 cPs
• Specific Gravity (Mixed): 1.11
• Gel Time: 40-44 minutes
• Continuous Service Temperature: -40°F to 200°F (-40°C to 93°C)
• Hardness: Shore D 82
• Elongation at Break: 4.0%
• Tensile Shear Strength (Aluminium, 25°C): 26.9 MPa
• Tensile Shear Strength (CFRP UD): 41.3 MPa

Approvals & Specifications

• Qualified to BMS 8-301 Class 2 specification
• Designed for aerospace composite structural repair applications
• Suitable for room-temperature or thermal curing processes

Typical Applications

• Permanent composite field repairs
• Bonding carbon fibre composite structures
• Structural bonding of aluminium and composite assemblies
• Repair of aerospace composite components
• Bonding metals, coatings and most engineering plastics

Compatibility & Safety Notes

• Ensure bonding surfaces are clean, dry and free from grease, oil, paint, wax and oxidation before application
• Chemical etching, sanding or grit blasting can improve bond performance
• Bring both components to room temperature before mixing
• Mix thoroughly at low speed to minimise air entrapment
• Assemble bonded parts while the adhesive remains wet
• Refer to the Safety Data Sheet (SDS) before handling and disposal

Packaging & Procurement

• Supplied as a two-component adhesive system (Part A and Part B)
• Part A Shelf Life: 3 months at 4.4-25°C (40-80°F) or 6 months when stored at or below -18°C (0°F)
• Part B Shelf Life: 12 months at 4.4-27°C (40-80°F)
• Store in a cool, dry location away from direct sunlight

Why This Product is Chosen for AOG / MRO

• Designed specifically for aerospace composite field repairs
• Can provide permanent repairs for service temperatures up to 200°F (93°C)
• Excellent bonding to composites, aluminium and engineered plastics
• Room-temperature curing simplifies field maintenance
• High chemical and hot-water resistance supports long-term durability
• Compatible with meter-mix-dispense (MMD) equipment for controlled application

Practical Suggestions for Your Team (AOG Mindset)

• Prepare repair surfaces thoroughly to maximise structural bond strength
• Accurately measure and mix the adhesive using the specified ratio
• Complete assembly within the available gel time
• Use elevated-temperature curing where practical to reduce turnaround time
• Maintain correct storage conditions to maximise product shelf life before deployment

Manufacturer / Aviation Spec Codes

• Product Name: EY3804
• Manufacturer: H.B. Fuller (Fiber Resin Aerospace)
• Product Type: Two-component epoxy structural adhesive
• Specification: BMS 8-301 Class 2
• Application: Aerospace composite repair and structural bonding