TEST PRACTICES FOR NEXT GENERATION AIRCRAFT CABIN …

ICAS 2000 CONGRESS

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Abstract

Next generation aircraft designs will have tofollow general tendencies as in the reduction ofdevelopment costs and product lead time, as aresult of the growing competition betweenaircraft manufacturers. Also a major goal foraircraft manufactures and operators is reliableand mature aircraft cabin systems at entry intoservice.

To comply with these requests new testpractices must be originated in compliancewith the developing system technologies,especially for next generation aircraft cabinsystems, due to the increasing significance ofcabin comfort and passenger entertainmentwhich the aircraft operator will require fortheir marketing strategy.

This paper describes the main contents ofthe development activities in the area of newtest practices for next generation aircraft cabinsystems.

The new test practices will combine a newgeneric test system architecture with testmethods & means in order to offer an increasedtest coverage and therefore a higher safetylevel in a cost and time effective way.

A new developed full-scale cabin systemintegration & verification test facility offers anearly demonstration of new cabin systemsfunctionalities and the testability ofinteractions between system hardware,controller and interfaces to other aircraftsystems before assembly of first aircraft.

1 Introduction

The technical & technological progress of∗

aircraft cabin systems will grow significantly inthe future and cabin comfort and passengerentertainment demands will also consequentlyincrease. There are several reasons for this.

The increase in aircraft cabin systemfunctionalities resulting from the newdeveloped electronic standards which gives riseto new cabin system technologies and newcabin and passenger oriented services (seefig. 1). The new information society willrequest in each transport vehicle (car, train,ship or aircraft) the same entertainment and thesame access to information sources and inter-communication as in the home. This has morethan one effect on the on-board aircraft cabinsystems. Firstly the development andintegration of these new electronic systemstechnologies and secondly, which may be ofmore importance, is the quick renewal andadaptation of the aircraft cabin systems,following a very fast self-acceleratingdevelopment on the private and businesscommunication technologies sector.

The integration from these extended cabinsystems functionalities and the simultaneousincreased application of system controlling &monitoring by SW leads to an increasing cabinsystems complexity, which requires morecomprehensive testing. A further increase of thecabin systems complexity is being derived fromthe new integrated modular avionic concept,which will be deployed to adapt future aircraft

∗ CASIV Project Team

TEST PRACTICES FOR NEXT GENERATIONAIRCRAFT CABIN SYSTEMS

H.J. Tews et al.∗∗∗∗DaimlerChrysler Aerospace Airbus GmbH

Kreetslag 10, 21129 Hamburg, Germany

Keywords: aircraft Cabin systems, Test Methods and Means, Test Facilities,System integration TESTS

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systems to the new electronic standards withouthaving to reorganize the complete systemconcept and to obtain standardized modules,e.g. for processing and power supply modules,which in turn reduces system weight and spaceas well as reducing the maintenance costs.

The future growth of air transport and theeconomical means of air transport requested,together with the introduction of extendedcabin systems functionalities and newintegrated modular avionics concepts, willrequire more cost-effective cabin systems withhigh dispatch reliability from the beginning ofentry into service. For a very large capacityaircraft, as the Airbus A340-600 or A3XX,dispatch reliability greater than 98% at entryinto service has to be guaranteed. Consideringthis, the development of a new standard of testpractices has to be in compliance with thetechnical / technological progress of nextgeneration aircraft cabin systems, their relatednew cabin system technologies and new cabinand passenger oriented services.

The purpose of this paper is to highlightthe main innovations regarding- new test strategiesnew test methods & means- new test facilitiesto verify & validate aircraft cabin systems intothe next century in an effective, safe andeconomic manner.

Complementary national and EuropeanR&D projects will provide a high-qualityknowledge base concerning new testtechnologies and validate these technologieswith experiments.

2 New Test Strategies

The SAE recommendation ARP 4754 proposescertification considerations for highlyintegrated or complex aircraft systems bysystems integration requirements [1] to ensurethe quality of the designed system before entryinto service. These considerations apply on onehand, to the design phase by a design assuranceconcept, which requires an identification of thesystem requirements from which the design

derived, and to validate that the design wassatisfy the system requirements. On the otherhand, the real product is tested and verifiedagainst the design and the requirements at eachlevel of the product design:- component level- system integration- lti-system or functional integration- rcraft level integrationand validated against aircraft functionalrequirements.

These processes and methods have beendefined for the certification of complex systemsand will be one of the most important sourcesfor the definition of new test strategies foraircraft cabin systems into the next century.

Another source for the development ofnew test strategies is the Airbus DirectiveABD 200 [2], which describes the completedevelopment process and includes thecertification considerations from the ARP4754. The ABD 200 is a basic document for allAirbus Industrie Partners and describes alsovalidation & verification processes to beexecuted for aircraft systems. Fig. 2 illustratesthe complete development process and theassociated documents acc. ABD 200.

The frames in fig. 2 indicate the areaswhere research & development activities havebeen started. The new developed test strategies[3] consider a high level system-wideexpression of major activities that collectivelyachieve the overall desired test results, asexpressed by the described validation &verification processes for aircraft systems in theABD 200.

These new test strategies are:- plementation of multi-system tests toenable the verification of the increased inter-dependencies between the new cabin systemsbefore ground & flight tests- plementation of system integration tests tomaximize the reliability of new systemtechnologies at entry into service and to reducenumber of aircraft ground & flight tests

TEST PRACTICES FOR NEXT GENERATION AIRCRAFT CABIN SYSTEMS

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- plementation of scalable test resources toenable an increase in resources for future cabinsystem technologies- plementation of a continuous computer-aided tool chain from the system design processto the systems test process to accomplish anincreased test coverage in a cost and timeeffective way- plementation of standardized simulationinterfaces to allow the interchangeability ofvalidated simulation models and simulationdata between Airbus Industrie Partners andsystem & component vendors- plementation of simulation models e.g. forpassenger behavior enabling a representativeenvironment to be tested before assembly offirst aircraft.

To achieve these new test strategies fornext generation aircraft cabin systems bestpractice studies [3] were performed to form ageneric Test System architecture for system,multi-system and system integration tests withnew test methods & means and new testfacilities.

3 New Test Methods & Means

The following describes the new Test Methods& Means which are the result of the bestpractice studies and will present the requiredmodules of the selected new generic test systemarchitecture (see fig. 3).

Test EngineThe Test Engine will process all interfaces toand from the System Under Test (SUT). Allbehavior simulations models and test scriptsgenerated by CATEGA shall run on the testengine. It has to simulate e.g. for the AirbusA3XX the passenger behavior of about approx.600 passengers and it has to be able to processapprox. 3000 interfaces and approx. 20 databuses in a frame rate of models between5 … 200 ms e.g. for the scheduled cabinsystems tests for the Airbus A3XX.

The acquired test data will be sent to theTest Data Management for further processing.

For an “unlimited capability” in thenumber of interfaces and computational powerfor future cabin systems tests the test enginemust have a “modular architecture” withstandardized HW-interfaces to provide theability to include simulation models fromdifferent simulation SW-tools.

In addition the test engine will allow anautomatic configuration control, self-tests andself-calibrating capabilities.

Simulation ModelsThe use of generated simulation models by thetest engine is the key input to perform theaircraft behavior- system behavior- equipment behavior- passenger behaviorfor representative tests before the assembly ofthe first aircraft.

Aircraft BehaviorThe simulation of the aircraft behavior isrequired to prepare the basic aircraft data e.g.speed, altitude, engine data etc. for the tests.

System BehaviorTo check the system functionalities it isnecessary to simulate the complete environmentof the system including all inputs e.g. sensorsimulations.

Equipment BehaviorThe equipment behavior has to be simulated,especially in the case of a fault simulation, tovalidate the behavior of the Build-In-Test-Equipment (BITE) functionality. Realequipment or simulations have to beexchangeable without re-configuration of thetest engine.

Passenger BehaviorThe possibility to simulate the passengerbehavior is one of the basic requirements on acabin systems test system. Only comprehensivesimulation capabilities allow computer-aidedtests with a high test coverage.

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Computer-aided Test Generation AssistantMain objectives of the novel computer-aidedtest generation assistant (CATEGA) are thestandardization of an automated test procedurepreparation process and the connection tospecific tools and data bases, which will bepartly applied in the system design process.

CATEGA will be directly connected to thecomputer-aided Requirements Tracing Manage-ment Tool (see fig. 4). The available data basedsystem & test requirements are used as thebasic inputs to be assigned to an automated testgeneration. Using this System RequirementsData Base permits the linking of test cases, testresults to the basic system & test requirements.The effect of changes of requirements on testcases and test procedures can be easilyfollowed and documented.

The second basic input of the systemdesign process is the data description in theTest Inter Systems Data Base. The Test InterSystems Data Base is a duplicate of the AircraftInter Systems Data Base used in the aircraftsystems design process and contains thecomplete description of all signals of theaircraft systems and the test system. Thedescriptions include all types of signals; analog,discrete, data busses etc. It includes also thesources and sinks of the signals and theirboundaries. Special extensions of the datamodel for test purposes make this data basedirectly usable for the computer-aided testgeneration, test data presentation and test dataanalysis.

The data of the Test Inter System DataBase will be used to define the sources andsinks of data, the point of observation (POO)and points of control (POC). Sources and sinkscan be real equipment and/or simulationmodels of systems or equipment.

The output-documents of the novelcomputer-aided test generation assistantCATEGA are:- Test Plan- Test Design- Test Cases- Test Procedures

- Test ScriptsThe test plan includes information about

the system, which functionalities are to betested. The test design describes the test object,test definition and the expected reaction of theSystem Under Test (SUT). The test cases arethe lowest level of test description. The testcases describe the single test steps with thedefinitions of Point Of Control, where tocontrol the inputs, the Point Of Observation,where to look or to measure and the expectedresult. Based on the test design we can combinenumbers of test cases together to produce a testprocedure. This combination will beperformed by considering e.g. the points ofcontrol, or the points of observation or the typeof measurement tool. The computer-aidedarranged test cases and procedures can also beused for a guided manual test execution.

For the complete automation of the testgeneration process, the test cases andprocedures can be used as an input for a testscript generation.

Test scripts based on test procedures butcontain additional information about the testenvironment, test engine etc. The requiredinformation will be stored in the test systemconfiguration data base. The test systemconfiguration data base will be used to controland document the configuration of the testsystem itself including the configuration of thesystem under test. The contents of the testsystem configuration data base will also be apart of the test data file in the archive to permita later re-configuration of the test system to thesame status for comparable tests of systems e.g.after modifications many months later.

The generated test scripts can be formed,after an adaptation to the original test engine,into an executable test program forautomatic tests.

The linked Test Preparation Data Baseis the related “results” data base of CATEGAand stores the generated output-documents.


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Human Machine InterfaceThe features of the human machine interfaceare responsible for the test system acceptanceand for the quality of test results. Thephilosophy is based on providing the testengineer with a maximum of flexibilityincluding the assistance of a novel tool box todisplay the data for indication, acc. to the actualtest situation and to allow the test engineer toselect the type of data presentation, numeric orgraphic, binary or in engineering units. All thenecessary aircraft panels & indications,simulations and test panels will be virtualpanels displayed on the test engineers monitorand easily adaptable.

The configuration of the test engine withthe human machine interface will be realizedvia connection to the Test Data ManagementTool.

Test Data ManagementThe Test Data Management Tool (TDM)captures the test data in real-time, stores datalocally, distributes the data to different usersvia an Ethernet network and in the futureexternal users will also be able to access thedata. The amount of test data to be stored inreal-time will be e.g. in the cabin domain of thenew very large capacity aircraft Airbus A3XX,worst case about 16.5 MegaBits per second,due to the high number of approx. 3000 cabinsystems interfaces, and several hundredMegabytes of data from approx. 20 data buses.

An additional function of the TDM is theoption to repeat tests. The integrated teach-infunction stores all performed manipulationsduring the test and allows the test to berepeated in the same time frame and with thesame interactions to compare the behavior ofdifferent versions of equipment and to have aneffective way to make comparable tests ofsystems e.g. same system with differentdevelopment statuses. A simple replay of testdata for further examination is also provided bythe TDM.

The TDM separates the test engine fromthe “non-deterministic” world of the test system

environment. The application of the TDMensures the undisturbed execution of real-timeprocesses in the test engine.

Test Data AnalysisThe Test Data Analysis made by the individualtest engineer who performs a free configurabledata reduction and puts the test data into formsthat can be used to deduce conclusions aboutthe system under test at the test process.

Test Data ArchiveThe Test Data Archive stores all test data filesinclusive of the test configuration data, relevantdata base files of requirements and signaldescriptions. In a worst case calculation arequirement to store 57 Gigabytes of test dataper hour must be achieved e.g. audio data fromcabin system. Additionally to the enormousstorage capacity, a fast access to test data andthe possibility to support several search criteriae.g. date of test, system configuration or testconfiguration must be achieved.

Data Base InterfaceThe Data Base Interface operates as astandardized interface for the different databases and ensures that a modification of a datamodel in one of the data bases does not affectany other data models.

4 New Test Facilities

From the general designed test objectives existsa requirement for two new types of test facilityfor multi-system and system integration tests.

Multi-systems test facilities allow the testof the inter operability of a network of systems,to check the effect of e.g. common modedisturbances on data busses or power supplies.These types of test facilities have to bedesigned to behave very closely to the realaircraft (aircraft in the lab). The installationenvironment for equipment, the length of wireharnesses, common power lines and thermalbehavior have to be carefully considered.

Following the test strategies it was decidedto design and build system test benches as well

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as multi-systems test facilities e.g. a CabinSystems Integration & Verification Test Rig.The design of both types of test facility followsthe requirements of new test strategies and willimplement the described new methods &means. The test facilities will use the samebasic HW and SW for test engine, the samedata bases and tools like CATEGA and testdata analyzing and archiving tools.

Fig. 5 shows an example of a simplifiedstructure of the system test bench for theCabin Inter Communication Data System(CIDS) with Signal switching and conditioningunits, fault insertion units, etc. and thepossibility to replace original equipment bysimulation of equipment for fault simulationand to allow automatic test execution bysimulation of passenger and cabin crew inputs.Based on the same generic architecture the testbenches can easily be connected together tobuild a multi-systems test bench with centraltest control and monitoring. All services andtools are designed for common use via theEthernet and will be centrally maintainedfollowing the general strategy.

According to the new test strategies aCabin Systems Integration & VerificationTest Facility (see fig. 6) as a multi-systems andsystem integration test facility based on aphysical full-scale mock-up of a A3XXfuselage and ready for installation of allcomponents of cabin systems and their wireharnesses, enabling all systems functions inparallel, will be developed. It will allow theinstallation of all necessary sensors andactuators and where necessary simulations. TheIntegration & Verification Test Facility will befully equipped with all cabin interior e.g.ceiling panels, seats, hat racks, galleys etc.. Itallows further the installation and testing of thecabin air systems to check passenger comfort.A central test control and monitoring also ofallows simulation the aircraft behavior anddifferent flight phases for tests. Fault insertionunits will be installed to generate commonmode failures to test the behavior of systems ina network. The power supplies of the

Integration & Verification Test Facility willalso allow the variation of voltages and offrequencies for tests.

The new Cabin Systems Integration &Verification Test Facility with a fully equippedcabin is also suitable for the demonstration ofthe passenger and cabin crew interfaces ofsystems, to verify the developed Man MachineInterfaces and to check maintenanceprocedures. This will support the earlyacceptance of the cabin systems by cabin crewsand passengers and ensure the smoothintroduction of new aircraft cabin systems.

5 Conclusion

The increased aircraft cabin systemsfunctionalities and new avionic technologiesrequires new test practices to accomplish theverification & validation process acc. thenewest regulations for aircraft systems.

On the basis of new developed teststrategies a new generic test system architecturein combination with new test methods & meansand new test facilities are described.

The development activities presented inthis paper describe a new approach to achievemore effective, safe and economic verification& validation processes. This work supports thegeneral goals to reduce the program risks and toobtain more reliable aircraft cabin systems atentry into service.

References

[1] SAE Technical Standard Board, ARP 4754,Certification Considerations for Highly-Integrated orComplex Aircraft Systems. Edition 1996, SAE,1996.

[2] Airbus Industrie, ABD 200, Requirements andGuidelines for the System Designer. Issue C, AirbusIndustrie, 1999.

[3] DaimlerChrysler Aerospace Airbus, Annual ResultsReport 1999 of the national R&D project CASIV.DaimlerChrysler Aerospace Airbus, 2000.


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New Test Practises

Extended Cabin Systems FunctionalitiesNew Integrated Modular Avionic ConceptExtended System and Test Requirements

New Test StrategiesNew Test Methods & Means

New Test Facilities

Next Generation Aircraft Cabin Systems

New Electronic StandardsNew Avionic Technologies

New Cabin System TechnologiesNew Cabin and Passenger oriented Services

New Safety Standards

A/C-FunctionalRequirements

System TLAR

TLSRDFRD

SRD

SDD

PTS

EquipmentPTS

Production

Qualification TestsEquipment Tests

Multi-System Tests

System IntegrationTests

Ground Tests

Flight Tests

Route Proving

System/EquipmentDevelopment

Vendor Responsibility

A/C-CertificationCertification Plan

Means of Compliance

Validation Plan

Validation Management

GTR

FTR

QTR

ATR

Certification Management

Test Requirements

Test Strategies

Test Technologies

SITR

TLAR Top Level Aircraft RequirementsTLSRD Top Level System Requirements DocumentFRD Functional Requirement DocumentSRD System Requirements DocumentSDD System Description DocumentPTS Purchaser Technical Specification

ATR Acceptance Test RequirementsQTR Qualification Test RequirementsSITR System Integration Requirements GTR Ground Test RequirementsFTR Flight Test Requirements

System Tests

Figure 2 Development Process and the Associated Documents acc. ABD 200 [2]

Figure 1 Impact of new Electronic Standards and new Avionic Technologies

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Test System

Test Results Data Base

Test Results Data Base

Real-TimeTemporaryData Base

Test Engine

Computer AidedTest Generation

Assistant

HumanMachine Interface(on-line/off-line )

TestData Management

Test Data Analysis

SimulationModels

Data Base Interface

Test Inter SignalData Base



TestPreparationData Base

TestPreparationData Base

Test EngineConfiguration

Data Base

Test EngineConfiguration

Data Base

TestRequirements

Data Base

TestRequirements

Data Base

TestRequirements

Data Base

System Under Test

Test Archiv

Figure 3 Selected new generic test system architecture

A/CInter SystemData Base

A/CInter SystemData Base

A/C-SystemConfiguration

Data Base

SystemRequirements

TestRequirements

SystemRequirements

Data Base

ComputerAided

SystemRequirements

Tracing Management

(RTM)

Test SystemConfiguration

Data Base

TestInter SystemData Base

ComputerAidedTest

GenerationAssistant(CATEGA)

ComputerAidedTest

GenerationAssistant(CATEGA)

Test PreparationData Base

Test Design

Test Plan

Test Cases

Test Procedures

Test Scripts

Test System

Test Logs

Test Incidents

Test Reports

TestInter SystemData Base

Test SystemConfiguration

Data Base

Test ResultsData Base

Design Process

Verification & Validation Process

Figure 4 Implementation of the novel Computer-Aided Test Generation Assistant (CATEGA)


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PISA-,IBU-,PSU/PIU-Simulation

DEU A


DEU A


DEU A


DEU A...

...

DEU B DEU B DEU B DEU B

AAP-, AIP-,ACP-, HS-,EPSU-, ...Simulation




CIDSDirector 1

FaultInsertion

andBreak-Out

Unit

...

...Test SystemTest System

Top-Lines Upper Deck

Mid-Lines Upper Deck

Misc. CIDS Equip.- PRAM- FAP- ...

Misc. CIDS Equip.- PRAM- FAP- ...

Other Systems- ECS- Water/Waste- ...

Other Systems- ECS- Water/Waste- ...

Crew Interfaces- Cockpit AIP- Cockpit Call Panel- ...

Crew Interfaces- Cockpit AIP- Cockpit Call Panel- ...

SignalSwitching

andConditioning

Original-PISA,IBU,PSU/PIU

Original-AAP, AIP,ACP, HS,EPSU, ...

CIDSDirector 2

CabinInfo

Server

Top-Lines Lower Deck Provisions

Mid-Lines Lower Deck Provisions

Mid-Lines Main Deck

Top-Lines Main Deck

Figure 5 Simplified Structure of a System Test Bench for the Cabin Inter CommunicationData System (CIDS)

Figure 6 Cabin System Integration & Verification Test Facility intended for the new Cabin Systems of the Very Large Capacity Aircraft A3XX