UWE Bristol Engineering showcase 2015

Stuart Andrews
BEng Electrical and Electronic Engineering
Project Supervisor
Nigel Gunton
Multifunction Test System for the GE Aviation ELMS Computing and
Communications Unit
Introduction
A large number of the engineering processes
carried out on the GE Aviation site at Bishop’s
Cleeve in Cheltenham are concerned with not only
the development and integration of new
technologies into power systems, but also the
sustainment of previously designed systems. One
such product is the Electrical Load Management
System used on the Boeing 777, developed in the
1990’s and still in use worldwide today: in life
service and repairs for systems supplied to the
aircraft manufacturer are essential for the
maintenance and service of the aircraft.
Part of this system comprises of a Computing and
Communications Unit which controls the power
distribution through the load management panel.
This line replaceable unit is also covered for repair
and replacement of each unit that is found to be
faulty. However, a significant number of faulty
units returned give “No Fault Found” on standard
test equipment solutions, leading to thousands of
pounds of testing and diagnosis time spent by
engineers. Because of this, a test solution is
required to more accurately diagnose the faults on
returned units to save money and increase the
business profit margin on these failed units: this
study focuses on the design and development of a
diagnostic suite to achieve this functionality.
Development
Company processes and procedures are driven by
guidelines and standards laid out both by federal
and government agencies and laws. Although it is
not necessary to go through the same extensive
processes necessary for qualification for flight, all
test equipment developed must be developed in
accordance with TS-PRO-001, the companies
process document defining “the process and
requirements for Engineering and Technology
(E&T) test solution development”. This process
document applies to all test systems development
and build projects in accordance with AS9100C
and ISO9001 quality standards.
The test systems engineering lifecycle follows the
“V” diagram , and illustrates an idealised flow
through the lifecycle. In practice, the flow is
iterative and repeatable.
Documentation
As with all industry standard equipment the
project was fully documented during
development, including circuit diagrams and a full
requirements specification.
Architecture
The architecture of the MFTS can be illustrated as
a functional block diagram. The system is designed
with flexible hardware that can be configured as
an ARINC629 Bus Analyser, card tester and flight
data/OFP delivery facility.
The core of the MFTS is designed around a
standard CCU “test board” currently used in
diagnostic test equipment: it is controlled by a
Raspberry Pi Model B single board computer using
the tester boards background debug mode
interfaces. The “test board” is also known as a
“golden card”, which is a card that is known to
have no defects and 100% functionality.
Custom boards were constructed to expand and
enhance the capacity and abilities of the
Raspberry Pi Model B (RPi B). There will be two
main upgrade elements: General Purpose
Input/Output (GPIO) expansion and a differential
interface for distribution of the RS485 SPI
capabilities.
Project summary
Engineering sustainment activities throughout a
products service life can prove to be the most
lucrative or costly part of the lifecycle. Performing
cost out activities on such processes can drastically
improve the profit margin of the product in question:
diagnostic testing and repairs times need to be kept
to a minimum to achieve this goal. This study
focusses on the design of a new test equipment
fixture for a GE Aviation unit currently in service to
enable diagnostics on failed units and cards returned
with defects to expedite one such process.
Project Objectives
The purpose of this project is to design and begin the
implementation of a prototype test system for the
ELMS2 CCU/CCC units. It is intended that the
specifications set forth in this project will provide a
suitable hardware/software baseline for further tests
to be developed for, with the report acting as a guide
and specification for the developed hardware.
Project Conclusion
A prototype test system for the ELMS2 CCC/CCU has
been studied and developed, including hardware
requirements, creation of the system architecture,
design and implementation of prototype hardware
modules and integration of the initial board layouts.
Some verification of the prototype has been carried
out. Small scale commercial SBCs can provide a
suitably stable platform for non-qualification or nonformal
testing with accompanying hardware.
Scientific Linux may be a good future alternative to
standard Windows solutions for future test fixtures.
The concept of the MFTS is shown to have clear
advantages over the current system in place:
development is costly in the short term, but the cost
benefit would outweigh the development resources
needed in the long term.