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OCR for page 233
SESSION m: DRIVERS FOR MATERIALS DEVELOPMENT
SESSION OBJECTIVES
Determine the drivers for development and application of advanced fire-resistant
materials.
PARTICIPANTS
Chair: Dennis Nollen, DuPont
Committee: lames Peterson, Boeing Commercial Airplane Group
Bruce DeBona, AlliedSignal
Participants: Fred Arnold, Federal Aviation Administration
Donald Cardis, Schneller, Inc
George Danker, Akro Fireguard Products
Thor Eklund, Federal Aviation Administration
Michael O'Donnell, Imi-Tech
Swen Schaich, Deutsche Aerospace Airbus
Martin Spencer, Heath Tecna
Marte} Zeldin, City University of New York Staten Island
SESSION REPORT
Current F'r+Res~stant Materials
Just as different materials have varying weight, cost, processability, and availability, they
also have varying fire resistance. For example, highly fire-resistant materials include poly-
benzimidazoles, polyquinoxalines, polyphosphazines, polyimides, phenolics, polyether-
ketonekelones, polyetheretherkelones, ceramics, and mews. Materials that have been modified
to meet current regulations include epoxies, polyesters (e.g., Trevira@), and polyurethanes (with
carbon).
Aircraft interiors are today made of materials of varying fire resistance, depending on
application and materials availability. Typical applications and current materials usage are
summarized in the following table. However, many of the available highly fire-resistant materials
find limited application in aircraft interiors because of the requirements for aircraft interiors such
as weight, cost, manufacturability, and end-use suitability.
233
OCR for page 234
234
Improved Fire- and Smoke-Resistant Materials
Applications
Materials
Floor and floor covering
Glass or carbon/epoxy or phenolic/Nomex~ honeycomb floor
panels
- flexible urethane seat track covers
- urethane foam edge band
Mylar0 film over galley and entry floor panels
Wool or nylon carpet
- double-backed tapes to attach carpet to floor
- Nomex. felt underlay (at customer request)
Polyvinylchloride galley mats
Lower sidewall panel Glass or carbon/phenolic/Nomex~ honeycomb plus scuff-resistant
surface (wool or Named fabric, or tough plastic)
Upper sidewall panel Glass or carbon/phenolic/decorative thermoplastic layer plus
Tedlar~
Light covers Polycarbonate
Overhead stowage bins Glass or carbon/phenolic/Nomex~ honeycomb plus edge urethane
foam layer plus reinforcement
Gap fillers Silicone or urethane
Passenger seats Wool, wool/nylon, or leather upholstery
Urethane foam cushions
Polybenzimidazole or Nomex@/Kevlar~ blocking layer
Polyethylene form flotation foam
Thermoplastic seat trays
Cabin attendant seats Wool, wool/nylon, or leather upholstery
Urethane foam cushions
Polybenzimidazole or Nomex@~/Kevlar~ blocking layer
Polyethylene foam flotation foam
Partitions Glass or carbon/phenolic/Nomex~ honeycomb
Decorative thermoplastic laminate or wool/Nomex~ textile or
leather
Polycarbonate transparent wind screen (infrequent)
Stowage bins Glass or carbon/phenolic/Nomex~ honeycomb
Decorative thermoplastic laminate
Wool textile interior liner (infrequent)
Placards Polyvinylchloride or urethane
Insulation Fiberglass bats, phenolic binder, Mylar cover
Polyvinylchloride/nitrile rubber, polyethylene, foams
Polyimide foam
Windows Outer pane stretched acrylic
Idner pane cast acrylic
Dust cover polycarbonate or acrylic
OCR for page 235
Part 11- Workshop Seminary
TABLE (continued)
235
Applications
Materials
Passenger service units
Hoses
Air ducting
Molded thermoplastics (Ultem@, Radel@, PEKK)
Aluminum
Glass or carbon/phenolic
Silicone
Nylon
Urethane
Glass/phenolic, epoxy, or polyester for large ducts
Polyisocyanurate foam for large ducts
Fire-retarded nylon
Glass/silicone
Nomex0 felt (small quantity)
Polyimide foam wrap
For non-aircraft applications, materials are generally used according to the requirements
of the application. For marry commercial applications, such as buildings, the fire resistance
requirements are not very stringent, so the materials used have less fire resistance than those
used in aircraft applications. In specially high-cost and vulnerable items such as manned space
vehicles and submarine applications where fire is an extreme hazard, materials that are more fire
resistant are used.
Design and Performance Requirements for Interior Materials
Design and performance requirements were not addressed in this session. The participants
fell that the conference papers on this subject by Hanns-Ioerg Betz, Swen Scha~ch, and Hans-
Dieter Berg were complete treatments of these topics.
Goals for fire Performance of Future Materials
Performance goals for improved materials for future applications were suggested by
participants. Commercialization of any new material for aircraft interiors requires, in addition
to flammability characteristics, economic viability, consistent manufacturing base, pleasing
aesthetics, cleanability, and low smoke and toxic product emission.
No Flashover. Full-scale tests conducted by the Federal Aviation Administration showed
that after flashover, escape from a post-crash fuel-fed fire was no longer possible. Thus a critical
step in improving survivability is to preclude flashover.
Uniform Requirements. Standardizing flammability requirements for all interior parts
would make materials selection simpler and would reduce the testing and development costs.
OCR for page 236
236
Improved Fire- arm Smoke-Resistant Materials
However, this would probably limit the availability of materials for the less critical applications,
since all materials would have to conform with the most stringent requirements.
Improved Burnthrough Resistance. Glass- and carbon-reinforced sandwich panels already
have adequate burnthrough resistance. Other materials could be substituted if their burnthrough
resistance was upgraded.
Retention of Mechar~ical/Physical Properties. Retention of physical and mechanical
properties of interior furnishings is important in maintaining the physical integrity of the
fuselage, which is crucial for passenger escape.
Totally Nonburrmble Materials. if totally nonburnable materials were developed that were
also appropriate for aircraft use, fire safety would be upgraded to the highest possible level.
Enclosed Air Circulation Systems. If materials could be adapted to enclose air circulation
systems and implemented within acceptable design constraints, fire containment could be
improved.
State of the Materials and Fabrication Industries
Although there is still adequate research capability within the materials and fabrication
industries, there has been a substantial curtailment of research capability over the past few years
with the downsizing of aerospace materials research. This is in part due to a downturn in the
defense industry activities and in part due to a downturn in the commercial aviation business.
For the materials industry to be able to respond effectively to the challenge of new materials
development in a unilateral way, there must be a clear signal that the effort will be supported
at government levels on a long-term and sustainable basis. Without this, there is a serious
question whether companies would be willing to commit their resources to such research. The
fabrication industry in turn will have to wall until materials are available before it can learn how
to fabricate parts from such materials.
Drivers and Barriers for the Development of Improved Materials
Session participants identified drivers for, and barriers to, the development and
implementation of new materials in commercial aircraft interiors. These are enumerated in the
following sections.
OCR for page 237
Part II - Workshop Summary
Drivers
.
.
Barriers
237
.
.
· The U.S. Congress recognized the need to pursue air travel fire safety by directing
the Federal Aviation Administration to establish research and development in this
area.
Materials suppliers and researchers are driven by the potential for a return on
investment. If materials with higher fire safety are developed, the developer will
expect to obtain return on investment.
Regulations provide a legal mandate that must be satisfied. If a material being used
causes a part to be noncompliant with new rules, changes must be made. Also, the
potential of anticipated future regulation would cause material manufacturers to
consider working on new materials in anticipation of a potential future profit.
Differences in regulations among worldwide regulatory agencies tend to drive the
implementation of materials and structures that are compliant with the most
stringent requirements, since the use of multiple materials for a common application
is costly. There has been a substantial effort to develop common regulatory
requirements across national boundaries (e.g., Federal Aviation
Administration/lAR, etc.~.
Life-cycle costs have been getting more attention recently. The effort to reduce the
cost of ownership for the airlines is a significant factor in the implementation of
new technologies. Life-cycle costs can be affected by material costs, fabrication
costs, or maintenance requirements.
Materials with good in-se~vice experience tend to see increased usage. Materials
with poor in-service experience or with histories of failures tend to be replaced in
subsequent design cycles.
Aircraft manufacturers have applied new materials unilaterally for many years to
provide product improvement or lower costs. Technologies that provide
product/process simplification while satisfying other in-use requirements will have
priority.
Weight reduction is a significant driver in aircraft design. Implementation of a
material that satisfies other in-use requirements at lower weight is favored.
Developments that have been funded with government or aircraft industry research
money are more likely to be implemented.
If a manufacturer spends research money to develop a material, there is a strong
motivation to receive a return on the investment.
· Both competition and partnerships work to foster further development.
Several barriers result from the way that the aircraft manufacturers do business.
Since cabin designs are upgraded with the introduction of each new aircraft model,
there are multiple designs for functionally similar parts with divided manufacturers
resisting technologies that were Not invented here."
OCR for page 238
238
Improved Fire- aM Smoke-Resistant Materials
.
Because of the aircraft industry's stringent engineering requirements, certification
procedures, expensive quality control, and part configuration control, changes to
existing designs are very difficult and costly.
The cyclic business environment of aircraft manufacturers causes serious problems
in materials manufacturers' ability to sustain long-term efforts in materials
development.
The nature and size of the market cause problems with the material suppliers.
Manufacturer's price is high, because niche materials sold at low volume are
expensive. It is very difficult to achieve implementation of a new, higher-cost
alternative without tangible, quantifiable benefits.
Without alternative uses for new developments to increase utilization, justifying
development of new materials for the limited market will be difficult.
Aircraft manufacturers are implementing shorter order-to-delivery time, decreasing
the time available to implement new materials in a production cycle.
The high cost of qualification and certification of a new material for aircraft
applications makes embarking on a material development and implementation
program risky for both the materials supplier and the aircraft manufacturer.
Downsized industry research organizations will have more difficulty performing the
work necessary to develop and commercialize new materials.
Government research programs can present barriers.
Inadequate cooperation or teaming among government, industry, and academic
organizations inhibit the interdisciplinary exchanges required for substantial progress
on fire-resistant materials.
Undertunded government research initiatives inhibit the initiation of long-term
research projects.
Issues concerning intellectual property rights are barriers to joint programs between
government, industry, and academia.
It is crucial that there be suitable test procedures and acceptance criteria that have inter-
and intralaboratory repeatability and reproducibility. Participants said that the poor
reproducibility of current regulatory test procedures have caused, and are still causing, extreme
problems.
Long-Term Research
.
Make long-term research a priority.
Establish acceptance criteria.
· Establish goals and requirements.
Establish repeatable and reproducible test equipment and procedures.
OCR for page 239
Part 11 - Workshop Summary
239
Establish joint development programs between government, academia, and industry.
Encourage development through prioritized government grants and contracts to
industry and academia.
Establish a forum for exchange of ideas and results.
Explore alternative design concepts.
Explore simplified configuration control possibilities for aircraft manufacturers.
Explore cooperative ventures between the Federal Aviation Administration and other
government agencies.
To make investment in fire-resistant materials more attractive, expand markets by
finding alternative uses for advanced materials, advanced materials concepts, and
advanced materials systems.
Explore promising technologies to improve existing materials, and to develop new
materials, modified materials, and hybrid approaches. Suggested activities include
new approaches to construction principles, testing, analytical modeling, and
processing.
Representative terms from entire chapter:
aircraft interiors
