Office of The Assistant Secretary Of The Navy
Director, Navy Safety and Survivability
Before The House Transportation and Infrastructure
Committee Oversight, Investigations, and Emergency Management Subcommittee
On Aircraft Electrical System Safety
5 October 2000
Not For Publication Until
Released By the House
Transportation And
Infrastructure Committee
Thank you, Madam Chairman and Members of the Subcommittee, for
inviting me here today to discuss the Navy Safety and Survivability
Office's efforts, to provide my assessment of progress toward improved
aircraft electrical system safety since your hearing in September
of last year, and to share this information with interested parties
from the aviation community. I would like to again commend the Subcommittee
for your continuing strong interest in this issue which is of such
critical importance to both military and civil aviation.
For those unfamiliar with the Navy Safety and Survivability Office,
I would like to briefly outline its history and mission. In August
of 1985, the Secretary of the Navy established an office for Safety
and Survivability, which is unique within the Department of Defense.
The focus of the Office was, and remains, twofold - find and bring
into the Navy's inventory state-of-the-art equipment that improves
our safety and survivability in military training and combat operations;
and raise the level of awareness of everyone - especially leadership
- of the need to prevent operational training and combat related
accidents. In short, stop injuries and the loss of critical assets.
Since 1985, we have taken actions that have saved many lives, improved
the ability of the Navy and Marine Corps to prevent losses and injuries,
and initiated efforts to share what we have learned with others
who might benefit from our experience and the information we have
assimilated.
Operational safety, which is the focus of my office, is slightly
different from "occupational safety and health" in that
it concentrates on actions that military operating forces employ
to accomplish their mission and, as in civil aviation, includes
elements that are not addressed by the Occupational Safety and Health
Administration. My office's safety interests, especially regarding
naval aviation, are often similar to those of civil aviation, and
sometimes lead to the identification of common problems for which
potential solutions can be shared. It is within this context that
my office became involved with the aircraft wiring issues.
As I summarized for the Subcommittee last September, the possibility
that a wiring problem may have been a causal factor in the TWA 800
tragedy led me to establish a combined government and industry forum
named the Aircraft Wiring and Inert Gas Generator Working Group,
now commonly referred to as AWIGG. The first meeting was in October
1998; and with one exception, AWIGG has met quarterly. This open
forum has facilitated information sharing between government and
industry by bringing together industry and military experts in aircraft
wiring and fire suppression. AWIGG's goals include ensuring that
all appropriate information in these areas is shared and understood
by all interested parties, and combining resources among interested
participants to accelerate the development of wire and fire suppression
technologies to enhance aviation safety. AWIGG membership now totals
more than 350 individuals representing military services, airlines,
aircraft and wire manufacturers, pilots and mechanics unions, researchers,
FAA, NTSB, NASA and others. The success of AWIGG is exemplified
by the recent establishment of a similar forum in Europe by some
of the current AWIGG participants. Information gained at AWIGG meetings
has been shared through briefings and technical papers presented
at conferences hosted by such prestigious organizations as the Society
of Automotive Engineers (SAE), Safety and Flight Equipment (SAFE)
Association, Flight Safety Foundation (FSF), and the FAA-NASA-DoD
Aging Aircraft Symposium.
Today I would like to provide a brief overview of the progress
made over the past year achieved by and/or presented to AWIGG, a
status of where I believe the aviation community is today, and actions
required for further improvement of aircraft electrical systems
safety.
The Navy, with more than 4,000 aircraft, has extensive experience,
data, and a strong interest in the evaluation and application of
state of the art aircraft wiring and electrical systems. Safely
operating and maintaining an aircraft fleet of this size demands
significant resources, a demand that becomes greater as the aircraft
age. As shown by the chart below, the average age of Naval aircraft
has continued to rise since the 1970s, adding considerable significance
to the concerns we have about the health of aging wiring. The Navy
currently operates over 2100 aircraft that are more than 15 years
old, 965 of which are more than 25 years old.
Source: Naval Air Systems Command
With the number and average age of the aircraft operated by the
Navy, the challenges being faced with respect to electrical systems
safety are at least equal to, if not more than, those faced by civilian
operators. Although the Navy and other Services sometimes encounter
issues unique to the military environment, there are many electrical
system problems common to all aircraft. The issues that I am addressing
today are applicable to the entire aviation community. There are
technologies and methodologies, at varying levels of maturity, that
address many of the wiring issues we face today. If community-wide
resources are combined to develop and field capabilities with the
greatest return on investment, more timely benefits can be attained.
While notable progress has been made, much more remains to be done.
At one time, aircraft wiring was assumed to last for the life of
the aircraft. As more has been learned about the aging characteristics
of wiring, that assumption has proven inaccurate, particularly as
military and civilian fleets continue to operate aircraft well beyond
their original design life. Evidence shows that as a wire system
ages, it may no longer meet all of its original performance standards,
necessitating additional inspections and health monitoring not envisioned
by its designer. Visual inspection, probably the most common inspection
technique, has been effective in detecting many wiring system discrepancies
in areas of aircraft that are accessible; however, visual inspection
cannot detect all faults which can lead to total system failure
and tragic consequences. Visual inspection alone is not sufficient
to ensure full knowledge of a wiring system's health. There have
been a number of non-visual inspection methods addressed at AWIGG.
Automated test equipment is available today that can monitor the
health of a wiring system and detect anomalies that could lead to
system degradation and/or failure. Methodologies have also been
developed that can incorporate this technology into a wire maintenance
program for aircraft operators. In addition, emerging technologies
offer even greater promise to safeguard against wiring system failures.
For example, the Navy, in conjunction with industry and academia,
is developing a technology called "Smart Wire" that should,
in a few years, provide real-time monitoring of aircraft electrical
systems. Also, technologies were presented at the last AWIGG meeting
by a scientist from the Lawrence Livermore National Laboratory that
could offer greater accuracy in detecting pending failures and defects
in aircraft electrical systems. Although there are diverse technologies
that can enhance the ability of aircraft maintainers to detect wire
defects before failure, no single solution addresses the electrical
systems safety issues we face today.
In addition to improvements in electrical systems inspections,
better methods for protecting wires and wire bundles are essential.
One technology, known as the Arc Fault Circuit Interrupter, or AFCI,
is being developed by a number of industry and government organizations,
including the Navy and FAA. The AFCI can detect and react to an
electrical arc much faster than the thermal circuit breaker currently
used in aircraft today. When an arc is detected, the AFCI can disable
the circuit and provide a warning that a fault exists. There has
been significant progress made over the past year in developing
AFCI technology, and prototypes should be available for testing
on aircraft in the near future. This is one of the most promising
near-term technologies for electrical system protection that has
been presented to the AWIGG forum.
Another important element that can affect an aircraft wiring system's
health is training. From efforts like the Aging Transportation Systems
Rulemaking Advisory Committee (ATSRAC), the aviation community has
much greater understanding of the importance of proper training
for maintainers and operators. Also, the NTSB's final report on
the TWA 800 tragedy called for increased emphasis on training in
the fundamentals of wiring systems' health for anyone who may come
in contact with wiring in an aircraft. From this focused training,
heightened awareness about wiring system health will increase the
likelihood of properly identifying and correcting damaged wiring,
and decrease the possibility of inadvertent damage to wiring during
maintenance or inspection activity.
To effectively deal with electrical systems safety, new materials
and installation methodologies must also be considered. New composites
hold promise for improved insulation materials that exceed the performance
standards met by wires currently used. A good example of composite
insulation is the combination of a PTFE outer layer over a polyimide,
which takes advantage of the complementary strengths of each, while
offsetting potential weaknesses. Advancements in material technology
have far surpassed the specifications that aircraft electrical system
wiring were initially required to meet. Experience gained over the
past three decades on how new wire insulation materials react to
aging, environmental exposure and routine system operation can be
better incorporated into minimum performance standards.
Improved construction and installation processes also need to be
considered. AWIGG participants recognize that typical wire bundling
can lead to chafing between different wire types and the potential
for electrical current from high voltage wires to migrate to low
voltage wires in the same bundle, an occurrence that becomes even
more likely as wires age. One example of improvement in construction
of wiring systems is the ribbonized wiring used on the V-22 Osprey.
In this particular application, ribbonized, organized construction
of wire bundles resulted in less weight and cost while enhancing
the safety and survivability of the electrical system. Replacements
for conventional wire systems have also been addressed; in particular,
fiber optics have been used by industry as an alternative for control
and indication functions. As in the case of wiring inspections there
does not appear to be one single best option for all applications.
Proper system engineering is required.
AWIGG forums have also identified a general lack of accurate data
on wire faults. During routine maintenance, wiring faults are often
not reported to an automated system capable of trend analysis or
hazard identification. It is difficult for industry to focus resources
on wiring improvements without supporting data. A robust reporting
and analysis system should provide this information. The just released
FAA Final Rule to improve reports submitted by certificate holders
and certificated repair stations, known as Service Difficulty Reports
(SDR's), should resolve this issue.
Advances in data collection and analysis technology have provided
modern aircraft health monitoring systems for virtually all components
such as engines, flight controls, and structural members. The health
of electrical systems must also be included in this routine monitoring,
and it appears that through the use of such technology as "Smart
Wire", the opportunity to conduct this monitoring may soon
be available. Therefore, early integration of these techniques with
health monitoring capabilities is essential to the safest possible
design of aircraft in the future.
Many other wiring related technologies and methodologies presented
by AWIGG participants warrant further evaluation. A complete listing
of AWIGG presentations is appended to the statement.
As I previously mentioned, AWIGG addresses not only aircraft wiring,
but fire suppression issues as well. I included fire suppression
as part of AWIGG 's focus because numerous in-flight fires have
occurred when an aircraft electrical system fails. The AWIGG has
reviewed a variety of fire suppression technologies, including some
in use by the military with potential for civil aircraft applications,
and others that are being used for non-aviation purposes but which
could be adapted for use on aircraft. Inert gas generators, used
for fire protection in the dry bays of the F/A-18E/F Super Hornet
and V-22 Osprey, and fine water mist systems developed by the Navy
as a Halon alternative for fire suppression on ships or aircraft,
have both been presented to AWIGG as potential technologies for
in-flight fire protection. Aircraft fuel tank inerting technology
used by the military, an area of growing interest, was also recently
briefed to AWIGG by Air Force representatives. Industry participants
have also shared information on chemically active aerosol generator
fire suppressants with fire protection capabilities, alternative
technology for water mist applications, and alternative sources
of inert gas for inerting fuel tanks.
To evaluate the viability of some of these technologies to control
and/or suppress aircraft interior fires in-flight, my office sponsored
and coordinated a proof-of-concept assessment of water mist and
aerosol generator fire suppression systems in May on a commercial
aircraft that had been removed from service. The assessment was
supported by both Navy and industry AWIGG participants. The Memphis
Group, an aircraft salvage firm headquartered in Memphis, TN, offered
the use of their facility in Greenwood, MS; and a B-737 aircraft
that had been removed from service. International Aero, Inc., based
in Burlington, WA, provided invaluable support through on-site technical
expertise and material procurement support needed to carry out the
assessments. Pyrogen, Inc., a Malaysia-based manufacturer/supplier
of aerosol generator canisters, provided on-site personnel and the
aerosol generator canisters for the test. Lectromechanical Design
Company, headquartered in Dulles, VA, provided the technical wiring
expertise to create electrical arcing and associated data collection/analysis
for the assessment. United Airlines provided technical insight to
the test aircraft for the development of the overall test plan.
In addition, the Navy provided technical and material support for
the tests, employing personnel from the Naval Research Laboratory
and the Naval Air Systems Command, along with contract support.
This proof-of-concept evaluation assessed the viability of using
only the existing onboard supply of water to create a fine water
mist to control and/or suppress in-flight fires in an aircraft interior,
and aerosol generator technology to control and/or suppress in-flight
fires in an aircraft's electronics bay. Both high pressure, approximately
1000psi, and twin fluid (water and air), low pressure (approximately
20psi) water mist systems were evaluated. Based on the findings
and conclusions from the evaluation, these technologies clearly
offer a viable means for enhancing an aircrew's capability to deal
with in-flight fires by either suppressing the fire or, at a minimum,
controlling it until handheld extinguishers can be used to fully
extinguish any residual pockets of flame. With further development,
fine mist and aerosol systems should provide aircrews with sufficient
time to make a successful landing, even to the degree of supporting
the FAA's 180-minute extended-range twin-engine operations (ETOPS)
criteria. Although further development of these systems is needed
to refine final system designs, the tests were highly successful
in proving that these concepts will work for in-flight fire suppression
and control. This successful proof -of-concept was made possible
by the combined commitment from both Navy and industry participants.
Based on the achievements and growth of knowledge of the past year,
the following recommendations are worth consideration by the Subcommittee
as aircraft electrical system safety enhancements:
a) Additional funding directed to accelerate the development and
production of Arc Fault Circuit Interrupter technology for the protection
of aircraft electrical systems.
b) Greater emphasis on the training of personnel to elevate awareness
of electrical systems issues, including recognition and reporting
of wire defects, proper maintenance and cleanliness procedures in
the vicinity of wire and wire bundles, and a better understanding
by operators of how to deal with wiring related problems.
c) Funding to continue the intrusive inspections and other non-structural
initiatives being conducted under the purview of the Aging Transport
Systems Rulemaking Advisory Committee (ATSRAC).
d) Funding to accelerate the development of "Smart Wire"
as a fulltime, onboard wire health monitoring system.
e) Greater emphasis on technology by aircraft operators to monitor
and assess the condition of wiring onboard in-service aircraft.
f) Funding to further develop water mist and aerosol technologies
as in-flight fire suppression systems.
g) Continued oversight of regulatory actions taken to address aircraft
electrical systems safety issues, such as establishing standard
aircraft circuit breaker reset policies by operators and improved
electrical system minimum performance standards that tie to the
technological advancements made since the current standards were
developed.
That concludes my prepared statement. I would be pleased to answer
any questions.
