Taking Flight: The Next Generation of Composite Core Material for Aircraft Interiors

October 29, 2015

For the Federal Aviation Administration (FAA), passenger safety is the main concern. Since the Aviation Safety Research Act of 1988, the FAA has increased the portion of its time and budget spent on researching fire safety, including testing which in-aircraft materials are most conducive to meeting these guidelines.

Enforcing Standards
As a result, in the past few years, potentially fatal in-aircraft fires, which are often due to the interaction between jet fuel and cabin materials, have managed to be contained. But there is always room for improvement, even with rigorous FAA requirements for aircraft interiors, which demand strength, stability, lightweight materials, and a low point of heat release.

Perhaps you're all too familiar with the plethora of standards that come hand-in-hand with the FAA, but we're taking a closer look at fire safety standards that affect material approval for commercial aircraft interiors: fire, smoke, and toxicity (FST) and Ohio State University (OSU) heat release standard.

What does OSU mean?
The OSU standard measures the rate at which materials release heat. This is especially important for aircraft interior materials, as they run the highest risk of igniting neighboring materials which are the closest to the passengers. There was a time where heat release rate measurements were viewed as laborious data to gather with limited practical value. Yet studies have shown that it may be the most crucial indicator as to survival probability in a fire.

Typically you'll hear OSU referred to as "OSU 65/65." What this means is that the FAA established a maximum acceptable two minutes total heat release (HR) and Peak Heat Release (PHR) of 65 KW min/m2 and 65 KW/m2 respectively – thus OSU 65/65. Different materials perform differently, however. For example, General Plastics' FR-3800 FST foam has a rating of <55/55.

What does FST mean?
Survivable crashes followed by a fire are typically caused by fuel spills near the aircraft. In these cases, passengers in the smoke-filled aircraft cabin are presented the very real danger of smoke inhalation. The FAA cites the inhalation of toxic gases in smoke as the primary cause of fatalities in most fires.

Therefore the FAA implemented standards for flammability, smoke, and toxicity to reduce the effects of smoke toxicity in the case of a cabin fire and thus prevent fatalities. Materials are tested for toxicity of their combustion products using time-to-incapacitation as the measured effect, and only materials with acceptable FST properties are chosen for an aircraft interior material.

What does that mean for the aerospace industry?
As the applications for such a material in commercial aerospace include class dividers, edge closeouts, hard points in composite panels, wall panels and ceiling panels, there is a great demand for a material that fulfills the fire, smoke and toxicity (FST) and Ohio State University (OSU) heat release standard.

How does General Plastics fit in?
General Plastics is helping aircraft manufacturers meet these new demands and requirements with our LAST-A-FOAM® FR-3800 FST Performance Core Series, the first halogen-free polyurethane-based foam formulation available in densities from 3 to 40 pounds per cubic foot that meets the FST and OSU 65/65 requirements for commercial aircraft interiors.

FST OSU foam core"We have a very successful line of polyurethane foam products that are used in aerospace as core materials," said General Plastics' Vice President of Materials Technology, Mitch Johnson, of the impetus behind creating FR-3800 FST. "As more metallic parts are replaced with composites, we knew that OEMs and Tier 1 and Tier 2 companies would need a product with excellent mechanical properties while also meeting the additional requirements for fire safety."

As a urethane-based material, FR-3800 FST is also priced very competitively compared to alternative core materials. According to Johnson, the material cost savings can be significant with little to no weight penalty. The advantages go beyond just a matter of cost, however.

"There are a lot of benefits to polyurethane foam over honeycomb," Johnson said. "Some of the advantages are ease of bonding, easy to make complex shapes, closed cell structure, isotropic structure and it is available in 24" thick sheets.

But what really sets FR-3800 FST apart is that we believe you can never be too careful. "General Plastics is somewhat unique in that we have FAA-certified testing facilities where we test our materials," Johnson said. "We are extremely diligent in testing and ensuring that we meet fire safety regulations. We make sure properties are never compromised and we monitor every batch of material manufactured." This testing regimen helps ensure that our products remain consistent over the life of the program, which could be decades long.

Our foam is a revolutionary introduction to the world of aerospace and we want to ensure it continues to exceed expectations.

Contact us today to learn more about the FR-3800 FST or how General Plastics serves the aerospace industry and meets rigorous quality standards.