Intelligent Telemaintenance
Wire Harness Integrity
Tester

By Hadi Shavarini

The wiring harnesses in an airplane, ship, submarine, automobile, or even large buildings,
are like veins in the human body. Wiring connects and distributes power and
communication signals to multiple systems that perform vital functions, such as electrical
power, communication, control signal and information.

 

For example, in an aircraft, the wiring system essentially is the infrastructure that connects
the electrical, electromechanical and avionics subsystems.  An aircraft, in average, contains
over 100 miles of complex wiring systems that includes insulated power and signal
conductors, fiber optics, connectors, protection devices (circuit breakers, and fuses) and
power distribution and control components. Wires are routed throughout an airplane in a
series of bundles with clamps and connectors. When the protective layer of insulation on a
wire is damaged and the conductor is exposed, it creates an electrical hazard potential for a
system malfunction and could short circuit or arc.  This could take place when
condensation bridges the gap between a wire conductor and an adjacent metallic structure.

 

The wire harnesses in an aircraft are subject to vibration, corrosion, and aging. It is very
difficult to know when one fails. And if one does fail, the result could be catastrophic. 
Short circuits that could lead to arcing could cause a fire that would be very costly to repair. 
The reliability and safety of wiring systems have become one of the most critical safety
concerns in aging flight systems.

 

An equally important point is that, today, aircraft are routinely flown well beyond their
original intended life. As a result, wiring failures have become a fire hazard and related
accidents are occurring at a rate of approximately two per month.  In fact, in a recent study
on Air Force aircraft mishaps or accidents, 43% of accidents were related to the wiring
interconnection system.  According to Honeywell, commercial aircraft had 1,089 smoke
and fire incidents over a 10-month period, of which 82% were directly related to electrical
systems.

 

Honeywell has long recognized the importance of safety, reliability, diagnostics, physics of
failure and prognostics, in an aircraft. 

NOVA Harness Data - Assigning a Harness to a Specific Aircraft

 

Honeywell has lead a team of industry experts and has developed the Wire Integrity
Program. According to Francois Gau, Director of Marketing at Honeywell Aerospace
Services, "The reliability and safety of wiring in older aircraft is a major concern of
operators throughout the industry." Honeywell has taken a pioneering role in addressing
these issues. 

 

NOVA, as it is called, is an integrated, and portable system designed and developed by
Honeywell to test and identify faulty wiring and connections in older aircraft.  The heart of
the system is the advanced modeling, diagnostics software and maintenance planning from
Qualtech Systems Inc. who is teaming up with Honeywell in this endeavor.

 

The Remote Diagnostics Server (RDS), from Qualtech, which was primarily developed
under NASA, is a key element of the NOVA system. NOVA performs wiring system
modeling, failure analysis, trend monitoring, prognostics, diagnostic analysis, and data
logging of test results and automatic test generation. The software enables operators to
optimize their wiring test and maintenance strategy within their current maintenance
processes.

NOVA Prognostics - Aircraft Wiring Status and Projected Test Dates.

According to Kevin Cavanaugh, Qualtech's Chief Operating Officer, "users can upload
test data to the RDS over the Internet or other network.  The data is then automatically
processed through the intelligent model-based reasoning in seconds, dynamically
generating an HTML web page display of the resulting diagnostics."

 

Using the RDS, intelligent dynamic tests, diagnostics, and maintenance procedures are
launched.  The operational integrity of the wiring systems is verified, and any fault
isolation ambiguity is resolved. The RDS software is web-based, and can even be
integrated with the supply chain system, logistics databases and computerized maintenance
management systems.

 

A distributed diagnosis solution, in the form of a Telemaintenance system, not only
monitors data streams, and embedded sensors in networked subsystems, but also
troubleshoots and diagnoses subsystem failures automatically, in real-time.  Additionally,
it provides ongoing health checks and finds areas that might become a problem, before
they are.

 

All of the capabilities of the RDS are automatic and intelligent (based on an expert model
of the system) thus eliminating the need for a group of experts in the "back room" as
required by some current remote diagnostic/monitoring systems.

 

The RDS architecture (patent pending) incorporates Qualtech's TEAMS™ 
(Testability Engineering and Maintenance System) software tool suite (TEAMS-RT™,
TEAMATE™, and TEAM-KB™) for real-time monitoring/diagnosis, interactive diagnosis
(driving interactive electronic technical manuals), and diagnostic/maintenance data
management, logging and trending.

Guiding the Technician - Intelligent Harness Inspection and
Test Procedures on NOVA.

This advanced diagnostics approach uses cause-effect failure models of the system to
perform comprehensive diagnostics right "out-of-the-box" eliminating the need for
expensive, data intensive, incomplete machine learning approaches, required by some
current case-based and neural network diagnostic systems. The TEAMS™ models of the
wiring harnesses within NOVA contain information and relationships involving the wiring
components (wires, connectors, pins, etc.), failure modes/effects, criticality, maintenance
cost/time, wire test methods, connectivity/dependency, and other parameters.  These
models provide the basis for extensive diagnostics analysis and the "Intelligence" in the
NOVA solution. The models also contain procedures, links to multimedia, and to the
run-time test scripts (for use with test equipment from other NOVA team members such
as DIT-MCO).

Test Execution - DIT-MCO Test Running on the NOVA Browser Interface

 

The use of real-time fault detection, and isolation solutions are essential to faster, less
expensive, and more effective operation of complex systems. This process reduces the
likelihood of operational failures and disasters due to a sudden failure, thereby improving
system safety and availability.

 

Francois Gau, believes that "Qualtech's software, along with other powerful features
within NOVA, empowers operators to diagnose and locate most any faults within the
wiring system. The system will, if required, test up to 5,000 wires in a minute and identify
almost any fault (shorts, open, insulation wear) and their location in the aircraft to within a
few centimeters."

 

Some of the benefits of NOVA can best be seen in manufacturing where it can help
quality standards with building and installation of the wire bundles.  Additionally, flight
line maintenance can quickly determine specific wires with faults and verify their location
and criticality.   NOVA can also help maintenance operators perform tests during scheduled
maintenance to check the wire integrity of the aircraft. 

 

The continuous real-time monitoring, failure detection, and isolation capabilities necessary
to maintain the constant operation and long-term health of complex wiring systems are
essential.  With the application of Telemaintenance to large-scale systems, three main
benefits are derived:

 

Improved Operational Safety: Root cause of pending failure and their criticality are
quickly and automatically identified and possibly mitigated.

 

Improved Availability: Since most of the system diagnosis is done online, and in
real-time, downtime for troubleshooting is minimized and life cycle costs or "cost of
ownership" is reduced.

Improved Confidence in System Serviceability: The resulting systems-wide
self-testing and monitoring capabilities of the RDS enable the health of the system to be
continuously and accurately accessed, with a high degree of certainty.

 

Honeywell claims about 3-10% of all maintenance hours are spent on wiring and estimates
that manual troubleshooting of an average narrow-body airplane could be reduced by 88%
(from $87,040 to $10,880) over four years. The end result is effective preventive
maintenance, locating faults and preventing accidents while reducing operating cost.

 

For further information visit Qualtech Systems, Inc. web site: www.teamqsi.com