Insights from industry

Structural Adhesives for Aerospace Components

Rohit Ramnath, Application Engineer for Master Bond Inc., talks to AZoM about their range of structural adhesives for in cabin and cargo compartment components inside aircraft and how they meet corresponding vertical and horizontal burn test specifications.

Which regulations in aviation manufacturing are related to flame retardancy of adhesives?

FAR standard 14 CFR 25.853(a) is used for determining material compatibility for structural adhesives in cabin and cargo compartment components inside aircraft. As stated by the test, the sample is put in contact with a flame for a specified amount of time and particular angle. The burn rate, burn length and time are then measured.

What is the difference between the vertical burn test and the horizontal burn test?

The primary difference between the vertical and horizontal burn tests are the burn angle and the burn time. The vertical test requirements are a bit more demanding compared to the horizontal test. However, the horizontal burn test is also very stringent and deemed adequate in many applications.

What products has Master Bond formulated that pass the horizontal burn tests as listed under the FAR standard 14 CFR 25.853(a) and can you tell us about their properties?

Master Bond EP90FR-H and EP90FR-HFL have both successfully passed the FAR 25.853(a) horizontal burn test. These flame resistant, non-halogenated epoxies are ROHS compliant and do not contain any SAVC’s per REACH standards. They feature convenient handling with good flow characteristics, excellent dielectric properties, and high bond strength.

EP90FR-H is easy to use, with a one to one mix ratio by weight. This moderate viscosity compound has a mixed viscosity of 20,000-50,000 cps at 75°F. Other product advantages include its superb electrical insulation, superior adhesion to a wide variety of substrates, and high dimensional stability.

EP90FR-HFL is a toughened system with an elongation of 30-40% at 75°F that can withstand rigorous thermal cycling. It has a long working life after mixing and a lower viscosity than EP90FR-H.

What are some of the applications that EP90FR-H and EP90FR-HFL can be used for?

These specialized epoxies can be used in a variety of aircraft applications involving acrylic windows, seat belts, structural window panes, lighted instrument assemblies and baggage equipment, for example.

What products has Master Bond formulated that pass the vertical burn tests as listed under the FAR standard 14 CFR 25.853(a)? Also, do you have any products that have low smoke and toxicity levels?

EP90FR-V passes the vertical burn test. It also passes Boeing specifications BSS 7238, Revision C for smoke density and BSS 7239, Revision A for toxicity. This is a two part system that features superior electrical insulation which makes it a great choice for electronic potting and sealing applications. Other product advantages are its convenient processing with a one to one mix ratio, excellent mechanical strength and long working life.

What are some of the applications that EP90FR-V can be used for?

This epoxy is often selected for aircraft applications such as interior panels, galley structures, door frame linings, stowage compartments, floor and door structures. It bonds well to a large variety of similar and dissimilar substrates, including metals, thermoplastics and composites.

Where can our readers learn more?

There is more information on The Master Bond website at where you can link directly to the flame resistant product pages discussed above. If you have a specific application to discuss, our technical experts can be reached at 201-343-8983 or you can fill out a request at and one of our experts will be in touch.

Rohit Ramnath

About Rohit Ramnath

Rohit Ramnath is an Application Engineer for Master Bond Inc., a custom formulated adhesives manufacturer.

He analyzes application-oriented issues and provides product solutions for companies in the aerospace, electronics, medical, optical and oil/chemical industries.

He graduated from Carnegie Mellon University with a Masters Degree in Chemical Engineering.

Disclaimer: The views expressed here are those of the interviewee and do not necessarily represent the views of Limited (T/A) AZoNetwork, the owner and operator of this website. This disclaimer forms part of the Terms and Conditions of use of this website.

Stuart Milne

Written by

Stuart Milne

Stuart graduated from the University of Wales, Institute Cardiff with a first-class honours degree in Industrial Product Design. After working on a start-up company involved in LED Lighting solutions, Stuart decided to take an opportunity with AZoNetwork. Over the past five years at AZoNetwork, Stuart has been involved in developing an industry leading range of products, enhancing client experience and improving internal systems designed to deliver significant value for clients hard earned marketing dollars. In his spare time Stuart likes to continue his love for art and design by creating art work and continuing his love for sketching. In the future Stuart, would like to continue his love for travel and explore new and exciting places.


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