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Cabin & Fire Safety Reports
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| Title: |
Comparison of Actual and Simulated Smoke for the
Certification of Smoke Detectors in Aircraft Cargo
Compartments |
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Summary: |
Federal regulations require that
aircraft cargo compartment smoke detection systems be
certified by testing their operation in flight. For safety
reasons, simulated smoke sources are permitted in these
certification tests. To provide insight into smoke
detector certification in cargo compartments, this
research investigates the morphology, transport, and
optical properties of actual and simulated smoke
sources.
Experimental data show the morphology of the particulate
in smoke from flaming fires is considerably different than
simulated smoke. The particulate for all three different
flaming fires was solid with similar morphological
properties. Simulated smoke was composed of relatively
large liquid droplets, and considerably different size
droplets can be produced from a single simulated smoke
machine. Transport behavior modeling showed that both
actual and simulated smoke particulate are sufficiently
small to follow the overall gas flow. However, actual
smoke transport will be buoyancy-driven due to the
increased temperature, while the simulated smoke
temperature is typically low and the release may be
momentum-driven. The morphology of the actual and
simulated smoke were then used to calculate their optical
properties. In contrast to the actual smoke, which is
dominate by absorption, all the extinction for the
simulated smoke is due to scattering. This difference
could have an impact on detection criteria and, hence,
time for photoelectric smoke detectors, since they alarm
based on the scattering properties of the smoke. |
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| Title: |
Computational Fluid Dynamics Code for Smoke Transport
During an Aircraft Cargo Compartment Fire: Transport
Solver, Graphical User Interface, and Preliminary Baseline
Validation |
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Summary: |
Current regulations require that
aircraft cargo compartment smoke detectors alarm within 1
minute of the start of a fire and at a time before the
fire has substantially decreased the structural integrity
of the airplane. Presently, in-flight tests, which can be
costly and time consuming, are required to demonstrate
compliance with the regulations. A physics-based
Computational Fluid Dynamics (CFD) tool, which couples
heat, mass, and momentum transfer, has been developed to
decrease the time and cost of the certification process by
reducing the total number of both in-flight and ground
experiments. The tool provides information on smoke
transport in cargo compartments under various conditions,
therefore allowing optimal experiments to be designed. The
CFD-based smoke transport model has the potential to
enhance the certification process by determining
worst-case locations for fires, optimum placement of fire
detector sensors within the cargo compartment, and sensor
alarm levels needed to achieve detection within the
required certification time. The model is fast running,
allowing for simulation of numerous fire scenarios in a
short period of time. In addition, the model is
user-friendly since it will potentially be used by
airframers and airlines that are not expected to be
experts in CFD. Following verification of this CFD code,
full-scale experiments have been initiated to aid in the
validation of the code and gauge the reliability of using
such an approach to increase the efficiency of the
aircraft fire detection system certification process. This
document includes a description of the CFD model, the pre-
and postprocessor, and the inital baseline validation
results. |
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| Title: |
Flammability of Aircraft Insulation Blankets Subjected to
Electrical Arc Ignition Sources |
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Summary: |
In the fall of 1998, the Federal
Aviation Administration (FAA) initiated a program of
intense testing, i.e., full-scale testing, intermediate
testing, bench-scale testing, and electrical ignition
testing on thermal acoustical insulation. This work was
prompted by several factors related to current fire test
requirements, including the crash of the Swissair MD-11
off the coast of Canada, and the failure of an industry
fire test standard called the cotton swab test to
characterize the flammability characteristics of a certain
foam and fiberglass cover material. Electrical testing was
an important part of this program due to the number of
reported incidents involving flame spread on thermal
acoustical insulation blankets caused by electrical
failures such as short circuits. The thermal acoustical
insulation films tested in this program were polyimide,
metallized and nonmetallized polyester poly (ethylene
terepthalate) (PET) and metallized poly (vinyl fluoride)
(PVF). Each of these materials was used to fabricate test
blankets with 0.42 pound per cubic foot (pcf) fiberglass
batting. The test blankets were subjected to 115-and
208-volt electrical arcing tests. This same testing was
performed on these blankets with a corrosion inhibiting
compound (CIC) sprayed on them. The data showed that the
metallized PET blankets ignited with significant flame
spread at both voltages with and without CIC. The
polyimide and metallized PVF blankets did not ignite at
either voltage when tested plain or with CIC application.
The plain PET blankets ignited at both voltages, with
minimal flame spread, and the fire self-extinguished
within seconds. When tested with CIC at 115 volts, flaming
in the seam area occurred but self-extinguished within
seconds. No ignition occurred at 208 volts. 17. |
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| Title: |
Limiting Oxygen Concentration Required to Inert Jet Fuel
Vapors Existing at Reduced Fuel Tank Pressures |
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Summary: |
This report discusses experiments to
determine the reduction in oxygen concentration required
to prevent a fuel tank explosion. A simulated aircraft
fuel tank containing JP-8 fuel of an amount equivalent to
a mass loading of approximately 4.5 kg/m3 was used to
determine the limiting oxygen concentration (LOC) at
pressures corresponding to altitudes ranging from 0 to 38
kft. In addition, the peak pressure rise was measured at
various altitudes (pressures) due to ignition occurring at
O2 levels approximately 1% to 1.5% above the LOC. |
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| Title: |
A
Description and Analysis of the FAA Onboard Oxygen
Analysis System |
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Summary: |
The Federal Aviation Administration
(FAA) is planning a series of ground and flight tests with
Airbus to prove the concept of a simplified fuel tank
inerting system, which has been developed by the FAA. The
FAA has also developed an onboard oxygen analysis system
to measure the oxygen concentration in the aircraft fuel
tank during the testing. To help ensure smooth integration
and the safety of the testing, the FAA has documented the
system description, interfaces, operation, and has
performed a failure mode effects criticality analysis.
This analysis attempts to identify the failure modes of
each system component and assess the effects of these
failures on the component, system, and aircraft. The
analysis also applies a hazard category to each hazard as
well as some hazard probability when it was deemed
necessary by the author. Hazard controls are also
listed. |
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| Title: |
Ground
Tests of Aircraft Flight Deck Smoke Penetration
Resistance |
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Summary: |
This report documents a series of
tests to determine the amount of positive pressure
differential between the flight deck and surrounding areas
necessary to prevent smoke from penetrating into the
flight deck. The testing also explored methods to
demonstrate the effectiveness of those ventilation
conditions. The tests were conducted on the ground in a
Boeing 727-100 freighter and a 747SP aircraft. A thin
plastic sheet covering the flight deck door opening and a
theatrical smoke generator were successfully used to
demonstrate a positive pressure differential that was
effective at preventing the penetration of theatrical
smoke into the flight deck of the B-727. The 747SP
ventilation system was not capable of preventing smoke
penetration during these ground tests. |
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| Title: |
Minimum Performance Standard for Aircraft Cargo
Compartment Halon Replacement Fire Suppression
Systems |
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Summary: |
This technical note presents the
updated version of the minimum performance standards (MPS)
that a Halon 1301 replacement or alternate system for
aircraft cargo compartment must meet as part of the
aircraft certification procedures. This standard considers
gaseous and nongaseous fire suppression systems for
full-scale fire testing. The Federal Aviation
Administration developed this MPS in conjunction with the
International Aircraft Fire Protection Systems Working
Group (formerly know as the International Halon
Replacement Working Group). |
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| Title: |
The
Response of Aircraft Oxygen Generators Exposed to Elevated
Temperatures |
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Summary: |
The purpose of this testing was to
determine the temperatures that would cause
self-activation of sodium chlorate oxygen generators. The
data will be used to establish the degree of thermal
protection that would be required to prevent the
activation of chemical oxygen generators should they be
exposed to heat from a cargo compartment fire involving
other materials. The minimum temperature that caused the
activation of one of the generators was 600°F. Due to
uncertainties with other designs not tested and the
physical properties of sodium chlorate, it is recommended
that the generators not be exposed to temperatures above
400°F. |
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| Title: |
A
Benefit Analysis for Cabin Water Spray Systems and
Enhanced Fuselage Burnthrough Protection |
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Summary: |
The purpose of this Analysis is to
evaluate the potential benefit, in terms of lives saved,
from enhanced Fuselage Burnthrough Protection and the
implementation of Cabin Water Spray Systems. The benefit
has been derived for each of these improvements being made
separately and in combination. Both Singular and Modular
Cabin Water Spray systems have been considered. A Singular
system is one that has a single source of supply and a
Modular system has multiple sources to provide improved
protection from damage that might be incurred under impact
conditions. |
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| Title: |
The
Correlation of Heat Release Calorimetry Measurements |
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Summary: |
The Ohio State University (OSU) Rate
of Heat Release Apparatus specified in FAR Part
25.853(a-1) defines both apparatus test conditions and
pass/fail criteria for large surface area aircraft
interior materials, such as sidewall panels, bulkheads,
and stowage bins. The cone calorimeter (ASTM E-1354
Standard Test Method for Heat and Visible Smoke Release
Rates for Materials and Products Using an Oxygen
consumption Calorimeter) similarly measures heat release
rates from materials subjected to a constant external heat
flux. However, heat release from the cone calorimeter is
calculated by measuring the decrease in oxygen
concentration in a stream of air flowing over the test
specimen, rather than the temperature (enthalpy) increase
of the air stream leaving the device, as is done with the
OSU Rate of Heat Release Apparatus. This report will
examine the differences between measurement of convective,
radiant, and total heat release rates, and discuss
techniques to obtain substantial conformity between the
two techniques. Results for both methods are compared for
single-ply, bisphenol-A epoxy-impregnated glass
cloth. |
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| Title: |
A
Benefit Analysis for Enhanced Protection from Fires in
Hidden Areas on Transport Aircraft |
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Summary: |
The purpose of this Analysis is to
evaluate the potential benefit, in terms of lives saved,
from enhanced protection from fires within hidden areas in
the aircraft cabin. For the purposes of this study, a
"hidden area" is defined as any area inside the
pressure shell, which is not readily accessible to the
crew other than a dedicated cargo area. |
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| Title: |
Burning Behavior Within a Seat Armrest Cavity |
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Summary: |
The purpose of this technical note
is to document the results of fire tests conducted to
examine the characteristics of fire that may occur in the
cavity of an aircraft seat armrest and the
fire-containment capability of the cavity. In all the
tests conducted with actual seat armrests, the fire
self-extinguished, the armrest materials did not ignite,
and the fire was contained within the armrest cavity. |
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| Title: |
Development of a Minimum Performance Standard for
Hand-Held Fire Extinguishers as a Replacement for Halon
1211 on Civilian Transport Category Aircraft |
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Summary: |
One or more Halon 1211 hand-held
fire extinguishers are specified in Federal Aviation
Regulation (FAR) Part 25.851 as a requirement on transport
category aircraft with 31 or more seats. Halon 1211 has
been linked to the destruction of the ozone layer and
production of new Halon 1211 has been halted per the
Montreal Protocol in 1993. The phase out of Halon 1211, as
the hand-held firefighting agent of choice, for civilian
transport category aircraft has necessitated the
development of a Minimum Performance Standard (MPS) to
evaluate replacement agents. The purpose of the MPS is to
insure that there is no reduction in safety, both in terms
of effectiveness in fighting onboard fires and toxicity to
the passengers and crew. |
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| Title: |
Combustibility of Cyanate Ester Resins |
|
Summary: |
Flaming and nonflaming combustion
studies were conducted on a series of polycyanurates to
examine the effect of chemical composition and physical
properties on the fire behavior of these cross-linked,
char-forming thermoset polymers. Heats of complete
combustion of the polymer and fuel gases were determined
by oxygen bomb calorimetry and pyrolysis-combustion flow
calorimetry, respectively. Fire calorimetry experiments
were conducted to measure the heat released, the rate of
heat release, and the smoke generation in flaming
combustion. Fire response parameters derived from the data
include the thermal inertia, heat of gasification,
effective heat of combustion, and combustion efficiency.
Halogen-containing polycyanurates exhibited extremely low
heat release rate in flaming combustion compared to the
hydrocarbon resins, yet produced significantly less smoke
and comparable levels of carbon monoxide and soot. |
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| Title: |
Inerting a Boeing 747SP Center Wing Tank Scale Model With
Nitrogen-Enriched Air |
|
Summary: |
Tests were performed in a 0.24 scale
model of a Boeing 747SP center wing tank to validate the
existing assumptions for inerting complex geometric
spaces, which were developed from previous experiments,
and to facilitate design of an efficient, cost- effective
inerting gas deposit system for full-scale, ground-based
inerting testing. The model was equipped with a variable
nitrogen-enriched air distribution system, thermocouples,
and oxygen analyzers that were monitored and recorded
continuously by a data acquisition system during each
test. The model was inerted in different configurations
with different flow rates and bay distributions. The
collected data was nondimensionalized in terms flow rate
and tank size to allow for comparisons between tests. |
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| Title: |
Fire-Resistant Elastomers |
|
Summary: |
Molecular design of semi-inorganic
rubbers has yielded flexible polysilphenylene-siloxane and
polyphosphazene elastomers having the fire resistance of
rigid, high-temperature engineering plastics (e.g.,
polyaramids, polyetherketones, and polyarylsulfones) based
on the results of microscale combustibility data. In
flaming combustion, a commercially viable polyphosphazene
exhibited a 75% reduction in heat release rate compared to
the polyurethane rubber currently used in fire- blocked
foam aircraft seat cushions. A comparable reduction in
heat release rate is obtained at lower cost by adding
expandable graphite flakes to the polyurethane
formulation. The graphite flakes exfoliate during heating
to produce a 2000% volumetric expansion of the burned
rubber which shields and insulates the underlying material
from the heat source and lowers the heat release rate
significantly. Future work will explore the use of
relatively low-cost expandable graphite technology in
semi- inorganic rubber to obtain a fireproof (zero heat
release rate) seat cushion foam. |
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| Title: |
Fire-Resistant Cyanate Ester-Epoxy Blends |
|
Summary: |
The cure chemistry, thermal
stability, and fire behavior in a series of fire-resistant
cyanate ester-epoxy blends were examined. The dicyanate
and diepoxide of
1,1-dichloro-2,2-bis(4-hydroxyphenyl)ethylene
(bisphenol-C, BPC) were combined in various molar ratios,
and the reaction chemistry was monitored using Fourier
Transform Infrared Spectroscopy (FTIR) and differential
scanning calorimetry (DSC). Fire behavior of the BPC
cyanate-epoxy blends was studied in flaming and nonflaming
combustion, using fire calorimetry and
pyrolysis-combustion flow calorimetry, respectively. |
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| Title: |
Heat
Release and Flammability Testing of Surrogate Panels |
|
Summary: |
A task group assembled under the
auspices of the International Aircraft Materials Fire Test
Working Group examined issues involving fire test approval
of previously qualified interior material systems
following renovation or alteration. A major problem
associated with the alteration of interior system
components is the difficulty in conducting certification
tests that would determine if the altered interior
component is still compliant with the heat release, smoke,
and flammability certification requirements. |
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| Title: |
Options to the Use of Halons for Aircraft Fire Suppression
Systems - 2002 Update |
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Summary: |
This report contains a summary of
available fire suppression agents and their properties.
The applicability of various technologies for each major
onboard aircraft application is assessed. Classes of
agents, with presently available agents listed, are
recommended for use in the development of test protocols.
The test protocol developed for a class of agents can be
used, with minor modifications, to test all agents
belonging to that class. |
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| Title: |
The
Evaluation of Water Mist With and Without Nitrogen as an
Aircraft Cargo Compartment Fire Suppression System |
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Summary: |
This report documents the full-scale
evaluation tests of a water mist system, with and without
nitrogen that would be available from an onboard inert gas
generation system (OBIGGS) against a series of
standardized aircraft cargo fires. These evaluation tests
followed the testing protocols specified in the Minimum
Performance Standard for Aircraft Cargo Compartment
Gaseous Fire Suppression Systems modified with a draft new
protocol for an exploding aerosol can fire scenario that
would be applicable to nongaseous systems. The
developmental work was performed in conjunction with the
International Aircraft Systems Fire Protection Working
Group. The results showed that a hybrid water mist and
nitrogen system met the minimum performance standard, with
lower cargo compartment temperatures than either plain
water mist or halon, and with less weight of water
consumed than halon. |
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| Title: |
A
Microscale Combustion Calorimeter |
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Summary: |
A method for measuring the heat
release rate of milligram-sized samples is described in
this report. Pyrolysis-combustion flow calorimetry (PCFC)
separately reproduces the solid-state and gas phase
processes of flaming combustion in a nonflaming test by
rapid controlled pyrolysis of the sample in an inert gas
stream followed by high-temperature oxidation (combustion)
of the pyrolyzate in excess oxygen. The rate at which the
sample releases its heat of combustion is calculated from
the oxygen consumption history. The heat of combustion is
obtained from the time integral of the heat release
rate. |
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| Title: |
Water
Spray as a Fire Suppression Agent for Aircraft Cargo
Compartment Fires |
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Summary: |
This report describes full-scale
fire tests conducted by the Federal Aviation
Administration (FAA) to investigate the effectiveness of
several types of water spray systems against in-flight
cargo compartment fires. Currently, commercial transport
cargo compartments are protected with Halon 1301 fire
suppression systems. Water spray is being considered as an
alternative agent for Halon 1301 which is no longer being
produced because of its ozone depletion potential. |
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| Title: |
Development and Performance of an Adiabatic Expansion
Nozzle for Improved Fire Extinguishers |
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Summary: |
A new fire extinguisher concept, the
adiabatic expansion nozzle, extends the usefulness of fire
extinguishing compounds by lowering the temperature and
discharge pressure of the agent. This allows total flood
type halon replacements to be used in hand- held
applications and, in the instance of carbon dioxide,
produces a low-pressure dry ice snow. |
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| Title: |
FLAMMABILITY OF AUTOMOTIVE CHILD RESTRAINT SEATS FOR USE
IN AIRCRAFT |
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Summary: |
Child restraint seat used in
aircraft are based on automotive designs that are required
to pass a horizontal burn rate test method. The
flammability of child seat materials was gauged against
the Federal Aviation Administration (FAA) vertical Bunsen
burner tests method. Basically, the vertical test
prescribed in Federal Aviation Regulation (FAR) 25.853
(a)(1)(ii) allows a burn length of 8 inches and flame time
of 15 seconds after exposure to a Bunsen burner flame for
12 seconds. |
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