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UWE Bristol Engineering showcase 2015

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Stuart Andrews<br />

BEng Electrical and Electronic <strong>Engineering</strong><br />

Project Supervisor<br />

Nigel Gunton<br />

Multifunction Test System for the GE Aviation ELMS Computing and<br />

Communications Unit<br />

Introduction<br />

A large number of the engineering processes<br />

carried out on the GE Aviation site at Bishop’s<br />

Cleeve in Cheltenham are concerned with not only<br />

the development and integration of new<br />

technologies into power systems, but also the<br />

sustainment of previously designed systems. One<br />

such product is the Electrical Load Management<br />

System used on the Boeing 777, developed in the<br />

1990’s and still in use worldwide today: in life<br />

service and repairs for systems supplied to the<br />

aircraft manufacturer are essential for the<br />

maintenance and service of the aircraft.<br />

Part of this system comprises of a Computing and<br />

Communications Unit which controls the power<br />

distribution through the load management panel.<br />

This line replaceable unit is also covered for repair<br />

and replacement of each unit that is found to be<br />

faulty. However, a significant number of faulty<br />

units returned give “No Fault Found” on standard<br />

test equipment solutions, leading to thousands of<br />

pounds of testing and diagnosis time spent by<br />

engineers. Because of this, a test solution is<br />

required to more accurately diagnose the faults on<br />

returned units to save money and increase the<br />

business profit margin on these failed units: this<br />

study focuses on the design and development of a<br />

diagnostic suite to achieve this functionality.<br />

Development<br />

Company processes and procedures are driven by<br />

guidelines and standards laid out both by federal<br />

and government agencies and laws. Although it is<br />

not necessary to go through the same extensive<br />

processes necessary for qualification for flight, all<br />

test equipment developed must be developed in<br />

accordance with TS-PRO-001, the companies<br />

process document defining “the process and<br />

requirements for <strong>Engineering</strong> and Technology<br />

(E&T) test solution development”. This process<br />

document applies to all test systems development<br />

and build projects in accordance with AS9100C<br />

and ISO9001 quality standards.<br />

The test systems engineering lifecycle follows the<br />

“V” diagram , and illustrates an idealised flow<br />

through the lifecycle. In practice, the flow is<br />

iterative and repeatable.<br />

Documentation<br />

As with all industry standard equipment the<br />

project was fully documented during<br />

development, including circuit diagrams and a full<br />

requirements specification.<br />

Architecture<br />

The architecture of the MFTS can be illustrated as<br />

a functional block diagram. The system is designed<br />

with flexible hardware that can be configured as<br />

an ARINC629 Bus Analyser, card tester and flight<br />

data/OFP delivery facility.<br />

The core of the MFTS is designed around a<br />

standard CCU “test board” currently used in<br />

diagnostic test equipment: it is controlled by a<br />

Raspberry Pi Model B single board computer using<br />

the tester boards background debug mode<br />

interfaces. The “test board” is also known as a<br />

“golden card”, which is a card that is known to<br />

have no defects and 100% functionality.<br />

Custom boards were constructed to expand and<br />

enhance the capacity and abilities of the<br />

Raspberry Pi Model B (RPi B). There will be two<br />

main upgrade elements: General Purpose<br />

Input/Output (GPIO) expansion and a differential<br />

interface for distribution of the RS485 SPI<br />

capabilities.<br />

Project summary<br />

<strong>Engineering</strong> sustainment activities throughout a<br />

products service life can prove to be the most<br />

lucrative or costly part of the lifecycle. Performing<br />

cost out activities on such processes can drastically<br />

improve the profit margin of the product in question:<br />

diagnostic testing and repairs times need to be kept<br />

to a minimum to achieve this goal. This study<br />

focusses on the design of a new test equipment<br />

fixture for a GE Aviation unit currently in service to<br />

enable diagnostics on failed units and cards returned<br />

with defects to expedite one such process.<br />

Project Objectives<br />

The purpose of this project is to design and begin the<br />

implementation of a prototype test system for the<br />

ELMS2 CCU/CCC units. It is intended that the<br />

specifications set forth in this project will provide a<br />

suitable hardware/software baseline for further tests<br />

to be developed for, with the report acting as a guide<br />

and specification for the developed hardware.<br />

Project Conclusion<br />

A prototype test system for the ELMS2 CCC/CCU has<br />

been studied and developed, including hardware<br />

requirements, creation of the system architecture,<br />

design and implementation of prototype hardware<br />

modules and integration of the initial board layouts.<br />

Some verification of the prototype has been carried<br />

out. Small scale commercial SBCs can provide a<br />

suitably stable platform for non-qualification or nonformal<br />

testing with accompanying hardware.<br />

Scientific Linux may be a good future alternative to<br />

standard Windows solutions for future test fixtures.<br />

The concept of the MFTS is shown to have clear<br />

advantages over the current system in place:<br />

development is costly in the short term, but the cost<br />

benefit would outweigh the development resources<br />

needed in the long term.

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