SEVENTH FRAMEWORK PROGRAMME Theme 7 Transport (including Aeronautics)

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Oct 29, 2013 (3 years and 9 months ago)

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PART B





SEVENTH FRAMEWORK PROGRAMME

Theme 7 Transport (including Aeronautics)






Proposal full title:


PIONEERING

AIRCRAFT
-
INTEGRATED

STRUCTURAL

SENSORS
.


Proposal acronym:


PACIS
.


Type of funding scheme:


Collaborative Projects (CP)


Level 1

(i) Small or medium
-
scale focused research project (CP
-
FP)






Work programme topics addressed (sequence indicates order of importance):






Challenge 3:
COMPETITIVENESS THROUGH INNOVATION.

A
ctivity
7.1.4
IMPROVING COST EFFICIENCY




1)
AAT.2013.4
-
4

M
aintenance, repair and disposal






Challenge 1: ECO
-
INNOVATION

A
ctivity
7.
1.1 THE GREENING OF AIR TRANSPORT




2
)
AAT.2013.1.1
-
2
A
erostructures


Name of the
coordinating person:




Prof. Dr. ir. Martine Wevers


KU Leuven (University of Leuven)

Name of the project manager:




Dr. Helge Pfeiffer


KU Leuven (University of Leuven)

Theme

7:

TRANSPORT

(including

AERONAUTICS)



Call

identifier:

FP7
-
(AAT)
-
2012
-
RTD
-
1


2

List of participants



No.

Participants organisation name

Abbr. in
proposal

Country

01



.
C
oordinator
.




KU LEUVEN (University of Leuven)

-

Research group of Materials Performance and Non
-
destructive Testing
(Department of Metallurgy and Materials Engineering, MTM)


-

Laboratory of Acoustics and Thermal Physics (Dept. of
Physics)




MTM


ATF

BELGIUM

02



METALOGIC

NV

MET

BELGIUM

03



DEUTSCHES ZENTRUM FÜR LUFT
-

UND RAUMFAHRT
(DLR
, German Aerospace Center)
-

Institute of
Composite Structures and Adaptive Systems

DLR

GERMANY

04



CEDRAT

TECHNOLOGIES SA

CED

FRANCE

05



RIGA TECHNICAL UNIVERSITY (RTU
)


Avia瑩on InV瑩瑵瑥

RTU

LATVIA





CENTRO DE TECNOLOGIAS AERONAUTICAS


(䍔A
)

䍔A

SPAIN





MEGGITT A/S

MEG

DENMARK

08



ASCO

Industries
N
V

ASC

BELGIUM

09



FRAUNHOFER INSTITUTE

for Manufacturing
Technology and Applied Materials Research in Bremen
(IFAM
)

IFAM

GERMANY

10



ASI ANALOG SPEED INSTRUMENTS GmbH

ASI

GERMANY

11



UNIVERSITY OF THE BASQUE COUNTRY
-

Applied
photonics group

EHU

SPAIN

12



LUFTHANSA
-
TECHNIK AG (LHT)

LHT

GERMANY

13



IBERÍA LÍNEAS AÉREAS DE ESPAÑA, S.A. OPERADORA
(IBERIA)

IBERIA

SPAIN

14



KLM Royal Dutch Airlines

KLM

NETHERLANDS

15



EUROPEAN AERONAUTICAL
SCIENCE NETWORK (EASN)

EASN

BELGIUM


Table
1

List of participants
.


Theme

7:

TRANSPORT

(including

AERONAUTICS)



Call

identifier:

FP7
-
(AAT)
-
2012
-
RTD
-
1


3


LIST OF PARTICIPANTS

................................
................................
................................
..............

2

GLOSSARY
................................
................................
................................
................................
.....

6

................................
................................
................................
................................

10

OUTLINE
1: SCIENTIFIC AND/OR

TECHNICAL QUALITY, R
ELEVANT TO THE TOPIC
S
ADDRESSED BY THE CAL
L

................................
................................
................................
.......

11

1.0

I
NTRODUCTION
................................
................................
................................
........................
11

1.0.1 Why structural
health monitoring?
................................
................................
....................

11

1.0.2. The SHM sensors and systems to be developed by PACIS at a glance

................................
.

12

1.0.3 Why PACIS needs public funding within the frame of a European project?
..........................

13

1.1

C
ONCEPT AND OBJECTIVE
S OF
PACIS

................................
................................
.......................
14

1.1.1 Pre
-
selected targets for PACIS in
operational aircraft or realistic full
-
scale parts

...............

15

1.1.2 PACIS concept of implementation

................................
................................
.....................

17

1.1.3 Relevance of S&T objectives with respect to the call

................................
..........................

19

1.2

P
ROGRESS BEYOND THE S
TATE
-
OF
-
THE
-
ART
................................
................................
..............
23

1.2.1 State
-
of
-
the
-
art

................................
................................
................................
................

23

1.2.2 Progress expected from PACIS

................................
................................
.........................

29

1.3

S/T

METHODOLOGY AND ASSO
CIATED WORK PLAN

................................
................................
....
30

1.3.1 Overall strategy of the work plan

................................
................................
......................

30

1.3.3 Detailed work description

................................
................................
................................

33

Table 1.3 a: Work package list
................................
................................
................................
..

33

Table 1.3 b: Deliverable list

................................
................................
................................
.....

34

Table 5 List of deliverables. Table 1.3c: List of milestones
................................
..........................

34

WP01


INSTALLATIONS IN AIRCRAFT


Planning, operational requirements and constraints
..

36

WP02


SHM SYSTEM
-

Percolation sensors for leaked liquids, fatigue cracks and corrosion
......

38

WP03


SHM SYSTEM
-

Optical Methods for detecting fatigue and impact damage
.....................

41

WP04


SHM SYSTEM
-

Guided acoustic waves for detecting fatigue and impact damage

...........

44

WP05


SHM SYSTEM
-

Electrochemical monitoring for detecting corrosion
..............................

47

WP06


AIRWORTHY OPERATIONS
-

Transducer selection,
self
-
testing and durability

.............

49

WP07


AIRWORTHY OPERATIONS
-

Electronics, RFID chips and ARINC bus access

..............

51

WP08


INSTALLATIONS IN AIRCRAFT
-

Installation and Validation
................................
.......

53

WP09


DISSEMINATION AND EXPLOITATION
................................
................................
.....

56

WP10


PROJECT MANAGEM
ENT

................................
................................
.........................

58

WP11 Table 1.3e: Summary of staff effort
................................
................................
..................

59

1.3.4 Graphical presentation of the interdependencies of workpackages

................................
......

60

2. IMPLEMENTATION

................................
................................
................................
..................

61

2.1

M
ANAGE
MENT STRUCTURE AND P
ROCEDURES

................................
................................
..........
61

2.1.1 Organisational structure

................................
................................
................................
..

61

2.1.2 Factors challenging the achievement of impacts

................................
................................

64

2.2 Individual participants
................................
................................
................................
........

67

2.2.1a KU Leuven


MTM (KUL
-
MTM)

................................
................................
....................

67

2.2.1b KU Leuven


ATF (KUL
-
ATF)
................................
................................
........................

68

2.2.2 METALogic nv

................................
................................
................................
................

69

2.2.3 Deut
sches Zentrum für Luft und Raumfahrt (DLR)

................................
.............................

70

2.2.4 CEDRAT Technologies SA

................................
................................
...............................

71

2.2.5 Riga Technical University (RTU)


Aviation Institute

................................
.........................

72

2.2.6 Centro de Tecnologías Aeronáuticas


(CTA)

................................
................................
....

73

2.2.7 Meggitt A/S

................................
................................
................................
.....................

74

2.2.8 ASCO Industries nv

................................
................................
................................
.........

75

2.2.9 Fraunhofer Institute
-

IFAM

................................
................................
.............................

76

2.2.10 ASI ANALOG SPEED INSTRUMENTS GmbH
................................
................................
.

77

2.2.11 University of the Basque Country (EHU)
-

ETSI de Bilbao

................................
...............

78

2.2.12 Lufthansa Technik AG (LHT)
................................
................................
..........................

79

2.2.13 Iberia Líneas Aéreas de España S.A. Operadora (IBERIA)

................................
...............

80

2.2.14 KLM Royal Dutch Airlines

................................
................................
.............................

81

Theme

7:

TRANSPORT

(including

AERONAUTICS)



Call

identifier:

FP7
-
(AAT)
-
2012
-
RTD
-
1


4

2.2.15 European Aeronautical Science Network (EASN)
................................
.............................

82

2.3

C
ONSORTIUM AS A WHOLE

................................
................................
................................
.......
83

2.3.1 Complementarity of partners

................................
................................
............................

83

2.3.3 Sub
-
contracting

................................
................................
................................
...............

84

2.3.4 Additional partners

................................
................................
................................
..........

84

2.4

R
ESOURCES TO BE COMMI
TTED

................................
................................
................................
85

3. IMPACT

................................
................................
................................
................................
....

86

3.1

E
XPECTED IMPAC
TS LISTED IN THE WOR
K PROGRAMME

................................
.............................
86

3.1.1 Main impacts
................................
................................
................................
...................

86

3.1.2 Contributions to scientific and technical state
-
of
-
the
-
art

................................
....................

87

3.1.3 Economical benefits

................................
................................
................................
.........

87

3.2

N
ECESSITY OF AN
E
UROPEAN APPROACH

................................
................................
..................
88

3.3

C
ONSIDERATION OF OTHE
R NATIONAL OR INTERN
ATIONAL RESEARCH ACT
IVITIES

......................
89

3.4

D
ISSEMINATION AND
/
OR EXPLOITATION OF P
ROJECT RESULTS
,

AND MANAGEMENT OF
INTELLECTUAL PROPERT
Y

................................
................................
................................
.............
89

3.4.1 Dissemination of results

................................
................................
................................
...

89

3.4.2 Exploitation of results

................................
................................
................................
......

89

3.4.3 Management of knowledge and intellectual property
................................
..........................

90

4. ETHICAL ISSUES
................................
................................
................................
.....................

91

5. CONSIDERATION OF
GENDER ASPECTS

................................
................................
............

93

LIST OF FIGURES

................................
................................
................................
.......................

94

LIST OF TABLES

................................
................................
................................
.........................

95

LITERATURE
................................
................................
................................
...............................

96








Theme

7:

TRANSPORT

(including

AERONAUTICS)



Call

identifier:

FP7
-
(AAT)
-
2012
-
RTD
-
1


5



Consorti um

p.
67

Work programme
p.
33

Ri sk Management
p.
64

Management

p.
61

I mpact p.
86

Concept

p.
14

State
-
of
-
the
-
art

p.
23

Theme

7:

TRANSPORT

(including

AERONAUTICS)



Call

identifier:

FP7
-
(AAT)
-
2012
-
RTD
-
1


6

Glossary

ACOUSTIC EMISSION
i s a passi ve acousti c techni que detecti ng sound created by di fferent ki nds of defects, such as
i mpacts, or cracks and corroded areas under vari abl e l oads.

AISHA
Acronym of “Ai rcraft Integrat
ed Structural Heal th Assessment


Al 2024
-
T3
Temperature
-
treated al umi ni um al l oy contai ni ng rel evant amounts of copper, i ron, manganese and
magnesi um, a standard for ai rcraft fusel age structures.

ARINC 429 STANDARD
Protoc
ol to connect di fferent el ectroni c systems i n an ai rpl ane, used by Ai rbus and Boei ng.

ASD

Aerospace and Defence Industri es Associ ati on of Europe.

BASE MAINTENANCE

i ncl udes the C and D checks requi ri ng one unti l si x weeks downti me, to be performed wi th
an a
pproxi mate i nterval of two or ten years.

BREWSTER'S ANGLE

i s the i nci dent angl e at whi ch the refl ected part of i nci dent unpol ari sed l i ght i s perfectl y
pol ari zed.

CFRP
Abbrevi ati on for carbon fi bre rei nforced pl asti c or carbon fi bre rei nforced pol ymer.

Down
time

i s a peri od when the ai rcraft i s not avai l abl e due to mai ntenance, repai r and overhaul acti vi ti es.
Addi ti onal downti mes are a major cost factor for ai rl i nes because the cost for one day downti me i s i n the range of
50.000 EURO, repai r costs not yet i nc
l uded.

EASA
Abbrevi ati on for European Avi ati on Safety Agency. It was establ i shed i n 2003 and took over a number of
functi ons of the JAA (Joi nt Avi ati on Authori ti es). EASA has a number of speci fi c regul atory and executi ve tasks wi th
respect to the ci vi l avi
ati on safety wi thi n the European Communi ty.

EDDY CURRENT METHOD
Moni tori ng of the i ntegri ty of structures can be carri ed out usi ng movabl e eddy current
sensors (coi l s). The moni tori ng of vari ati ons i n the eddy currents due to the presence of cracks.

ENGINE
ERING ORDER
Document used i n Mai ntenance, Repai r and Overhaul descri bi ng changes of e.g. the
ai rframe structure.

FATIGUE TEST
Tests where structures are subjected to cycl i c mechani cal al ternati ng l oadi ng e.g. si mul ati ng fl yi ng
condi ti ons.

FAA

Federal Avi at
i on Admi ni strati on (FAA): the nati onal avi ati on authori ty of the Uni ted States of Ameri ca

FULL
-
SCALE PARTS
In the context of
PACIS
, ful l
-
scal e parts represent al l target components actual l y used i n
di fferent ki nds of real ai rcraft. The si ze of the parts i s

usual l y suffi ci ent to
be representati ve for real si tuati ons
.

GALLEY
Ki tchen i n an ai rpl ane.

HINGE ARM
i s a l oad carryi ng movabl es at the l eadi ng edge of a wi ng (connected to droop nose).

INSPECTION SERVICE BULLETIN
Document del i vered by an ai rcraft
manufacturer descri bi ng changes of the
i nspecti on procedures.

MINOR/MAJOR CHANGES
: Accordi ng to EASA CS
-
21: Changes i n type desi gn are cl assi fi ed as mi nor and major. A
‘mi nor change’ i s one that has no appreci abl e effect on the mass, bal ance, structural st
rength, rel i abi l i ty,
operati onal characteri sti cs, noi se, fuel venti ng, exhaust emi ssi on, or other characteri sti cs affecti ng the
ai rworthi ness of the product. Wi thout prejudi ce to 21A.19, al l other changes are ‘major changes’ under thi s
Subpart. Major and m
i nor changes shal l be approved i n accordance wi th 21A.95 or 21A.97 as appropri ate, and
shal l be adequatel y i denti fi ed. The cl assi fi cati on and approval process are al so defi ned i n the CS
-
21 standard.

MAINTENANCE SCHEDULES
consi st

usual l y of Li ne, Li ght and
Heavy Mai ntenance (“BASE
-
mai ntenance” accordi ng
to the EASA rul es). The speci fi c procedures concerni ng ti metabl e as wel l as i nspecti on and repai r requi rements are
determi ned wi th the MSG
-
3 method (Mai ntenance Steeri ng Group) and speci fi ed wi thi n the MPD (M
ai ntenance
Pl anni ng Data) by the respecti ve manufacturers. Thi s document establ i shes the basi s for the mai ntenance
schedul e. Li ne Mai ntenance i ncl udes pre
-
fl i ght, dai l y and weekl y i nspecti ons duri ng normal operati ons, thus
outsi de the hangar. Li ght Mai nten
ance consi sts of the
A
-
checks

performed i n the hangar overni ght or wi thi n 24
hours, and the i nterval between such routi ne checks i s about 2 Months. The so
-
cal l ed Base Mai ntenance i ncl udes
the
C
and
D checks

requi ri ng one unti l si x weeks downti me, and they
wi l l be performed wi th an approxi mate
i nterval of two or ten years.

MPD
Mai ntenance Pl anni ng Data: Documents provi ded by manufacturers for ai rpl anes contai ni ng i nformati on for
customi zed and schedul ed mai ntenance.

MSG
-
3

(Mai ntenance Steeri ng Group) establ i
shed by i ndustry and mai ntai ned by ATA (Ai r Transport Associ ati on)
to regul ate i ssues rel ated to mai ntenance and i nspecti on tasks concerni ng ai rcrafts i ncl udi ng the respecti vel y
requi red i nterval s for an ai rpl ane.

PACIS
Acronym for


Pi oneeri ng Ai rCraft
Integrated Structural Sensors”

PERCOLATION CONDUCTIVITY
Composi tes, i f appropri atel y mi xed, wi l l exhi bi t percol ati on conducti vi ty i f
el ectri cal l y conducti ng parti cl es are embedded i n an el ectri cal l y i nsul ati ng matri x. The respecti ve composi te wi l l
change f
rom el ectri cal l y i nsulating materi al to a conducti ng materi al dependi ng on admi xture rati os, i nfl uenced by
penetrati ng l i qui ds or external stress.

Theme

7:

TRANSPORT

(including

AERONAUTICS)



Call

identifier:

FP7
-
(AAT)
-
2012
-
RTD
-
1


7

POF
Pol ymer Opti cal Fi bre
.
Thei r

advantage wi th respect to gl ass fi bres are l ower coupl i ng l osses and hi gher
crack
resi sti vity. They al so offer di fferent possi bi liti es for structuri ng and i ntake of agents.

However, appl i cati on i s l imi ted
i n the case of extreme temperatures and temperature gradi ents
.

PSEUDO
-
DEFECTS

Conce
pt where the materi al i s subjected to non
-
destructi vel y appl i ed mechani cal components,
creati ng scatteri ng l eadi ng to refl ecti on or attenuati on of ul trasoni c waves appeari ng si mi l ar as real defects.

PZT
Abbrevi ati on for l ead zi rconate

ti tanate, one of the standard materi al s for maki ng pi ezocerami cs.

LAMB

WAVES
Gui ded

ul trasoni c waves propagati ng al ong pl ate
-
l i ke structures (
Fi gure
3
), al so cal l ed pl ate waves.

MARAGING STEEL
Iron al l oy (l arge percentage of ni ckel ) exhi bi ti ng excel l ent strength and toughness, i n the project
i nvesti gated as the materi al for sl at tracks.

MRO
Abbrevi ati on for Mai ntenance, Repai r and
Overhaul

NDT
Abbrevi ati on for “non
-
destructi ve testi ng”, a col l ecti ve term of al l techni ques where of structures can be
tested concerni ng requi red properti es wi thout destroyi ng the materi al.

OEM

Ori gi nal Equi pment Manufacturer.

RAYLEIGH WAVES

Gui ded

ul trasoni c waves propagati ng at the surface of bul k materi al s, al so cal l ed surface
acousti c waves.

STRUCTURAL HEALTH MONITORING (SHM)
Inspecti on of the rel i abi l i ty concerni ng the structural i ntegri ty and
respecti ve l oad carryi ng capabilit
y of structures provi di ng mechani cal stabi l i ty
.
Those technol ogi es frequentl y use
permanentl y attached sensors and sensor networks. The term conti nuous does not requi re permanent
i nspecti ons, the “sampl i ng rate” of i nterrogati on i s determi ned by the progre
ss of damage propagati on. As
PACIS

i s
avoi di ng i nterrogati on duri ng fl i ght, the sampl i ng rate for the technol ogi es proposed i s the ti me between fl i ghts.

SME
Abbrevi ati on for “smal l and medi um si zed enterpri se”.

SLAT TRACK
A sl at track i s a beam movabl e i n
a gui de that connects i.e. the wi ng wi th the l eadi ng
-
edge sl ats,
capabl e to carry respecti vel y hi gh l oads.

Technology Readiness Level
, the
TRL

i s especi al l y used i n aerospace, sl i ghtl y di fferent defi ni ti ons are appl i ed and
economi cal aspects are usual l y no
t consi dered. The
adapted
European Space Agency (ESA) defi ni ti ons are:

TRL1

Basic principles observed and reported


TRL2


Technology concept and/or application formulated

TRL3

Analytical & experimental critical function and/or characteristic
proof
-
of
-
concept

TRL4

Component and/or breadboard validation in laboratory environment

TRL5

Component and/or breadboard validation in relevant environment

TRL6

System/subsystem model or prototype demonstration in a relevant environment (ground or
in
-
flight
)

TRL7

System prototype demonstration in
-
flight

TRL8

Actual system completed and "Flight qualified" through test and demonstration (ground or
in
-
flight
)

TRL9

Actual system "fl
ight proven" through successful
operations

TOPICS
i n the FP7 cal l s

are

detai l ed

sub
-
categori es of “
acti vi ti es
” and “
chal l enges
” that cl earl y descri be the
requi rements a consorti um shoul d respond to wi th i ts research proposal. The fol l owi ng topi cs
(ori gi nal l y taken
over from the work programme)
are addressed by the
PACIS

consorti um. The
phrases
i n
bold
are speci fi cal l y
tackl ed by the proj ect proposal:

TOPIC
AAT.2013.4
-
4. Maintenance, repair and disposal
-

Level 1
-

CP
-
FP
-

Call: FP7
-
AAT
-
2013
-
RTD
-
1


Content and scope: Research and i nnovati on on processes and technol ogi es for mai ntenance,

repai r and di sposal wi l l focus on i mprovi ng cost effi ci ency whi l e taki ng i nto account the
envi ronmental and safety rel ated aspects. Proposal s coul d add
ress the fol l owi ng subjects:


Cost efficiency:
• Advanced concepts and techni ques for:

-

continuous inspection of structures and systems allowing on
-
time maintenance and

eliminating unscheduled maintenance;

-

‘smart’ on
-
condition maintenance systems, inclu
ding self
-
i nspecti on and sel f
-
repai r

capabi l ities up to ‘mai ntenance
-
free’ ai rcraft; and

-

cost
-
effi ci ent repai r and overhaul operati ons appl i cable at the gate or at the workshop

i ncl udi ng ti me and cost
-
effi ci ent l ogi sti c processes for the suppl y of parts.

The rel evant certi fi cati on strategi es shoul d be devel oped i n paral l el wi th the research

work.

Greening:
• Advanced concepts and techni ques for:

-

el i mi nati on of
toxic chemicals

and materi al s and
reduction of waste in maintenance

operations
;

-

i ncreased r
e
-
use of components; and

-

increasing the life
-
time of aeronautical products
and for ful l recycl ability at l i fe
-
end i n a
safety neutral approach.

Safety:
• Advanced concepts and techni ques for:

-

continuous health and usage monitoring (e.g.
non
-
destructive testing, signal

processing techniques); and

-

avoidance/mitigation of structural corrosion.

Theme

7:

TRANSPORT

(including

AERONAUTICS)



Call

identifier:

FP7
-
(AAT)
-
2012
-
RTD
-
1


8


AAT.2013.1
-
2. Aerostructures
-

Level 1
-

CP
-
FP
-

Call: FP7
-
AAT
-
2013
-
RTD
-
1

Content and scope
: Research and i nnovati on on aerostructures wi l l focus on the greeni ng of

ai r transport whi l e taki ng i nto account the cost effi ci ency and safety rel ated aspects. Proposal s

coul d address advanced concepts and technol ogi es for the fol l owi ng subjects:



Gr
eening:

• Increased and opti mi sed use of l i ght
-
wei ght metal l i c, composi te materi al s, i ncl udi ng

metal l ami nates, i n pri mary structures; appl i cati on of
‘smart’ materials,

mul ti
-
functi onal

materi al s, mi cro and nano
-
technol ogi es; ‘smart’ structure
s and morphi ng ai rframes wi th

a potenti al to reduci ng greenhouse gas emi ssi ons; and masteri ng aero
-
el asti ci ty i ssues.

Cost efficiency:

• Devel opment of hi ghl y i ntegrated structures wi th opti mum combi nati on of advanced

metal l i c and composi te

materi al s el i mi nati ng or mi ni mi si ng the number of

joi n/assembl y el ements.



Increased integration of additional functions (sensing, actuating, electromagnetic,

electrical conductivity, etc.)

i n structural components for wi der ‘greener’ ap
pl i cati ons at

l ow cost and wei ght.

Safety:

• Experi mental val i dati on for i mproved protecti on agai nst crash, i mpacts and bl ast l oads,

i ncl udi ng passi ve and acti ve
‘smart’ aerostructures
, to ensure safety of agi ng ai rframe

and engi ne structures.

THERMO
GRAPHY
i s abl e to detect temperature di fferences by i magi ng i n the i nfrared. Defects i n materi al s and
structural components can be characteri sed by thei r di fferent response wi th respect to transferred modul ated or
pul sed heat.



Theme

7:

TRANSPORT

(including

AERONAUTICS)



Call

identifier:

FP7
-
(AAT)
-
2012
-
RTD
-
1


9


The world is moving so
fast these days that when a
person says it cannot be done, he is interrupted by
someone who is already doing it.”



---

Harry Emerson Fosdick
---


Theme

7:

TRANSPORT

(including

AERONAUTICS)



Call

identifier:

FP7
-
(AAT)
-
2012
-
RTD
-
1


10


OUTLINE




Maintenance, repair and overhaul (MRO) in modern
aviation is well
-
elaborated, but relatively

WHY
expensive

and
not appropriate

in all situations,
mainly because
inspections are
usually
performed
within fixed time intervals. A cheaper
, more durable
, greener

and even safer alternative
is
offered by
“structural health monitoring (SHM)”. SHM systems can b
e realiVeT by
per浡nenW

sensor networks

that are placed on crucial structural components of an aircraft, comparable to the nervous system in a
human body.
The last two decades
, SHM solutions were presented on laboratory scale and even
partially implemented

in real aircraft parts. However, the final implementation in
operational

airliners is
still in a

very
early phase and partially hindered by obstacles,

such as

missing
operational

practice,

respective technical immaturity and consequently a lack of accepta
nce by end
-
users.



The
PACIS

project intends
applying
physical phenomena,

such as

electrical
WHAT IS THE CHALLENGE
percolation conductivity,
electrochemical
impedance
,
optical polarisation and
ultrasonic
guided
waves
to
pioneering sensors and data algorithms
systems
for detecting
different kind of
relevant
defects.
In
this context, t
o achieve the ambitious milestones of PACIS, a

number of challenging
new
technologies
are proposed, such as
painted crack gauges, active remo
val of corrosive liquids

by a micro
-
ventilation
system or the combination of SHM with traditional non
-
destructive testing.
Beside the
development of
new type of sensors

and sensor systems,
an
innovative approach

for a
streamlined
implementation
strategy
for
SHM

is proposed
.
A part of the

PACIS
SHM
systems will
in the scope of the project
be
implemented in operational airliners as
minor changes
on hot spots

consequently achieving TRL 6

in an
in
-
flight
environment
,

enabling early added values by minimising
implementation thresholds. The
consortium will thus
develop
solutions that finally focus on robustness and especially on a smart
combination of
pre
-
existing certified

components/materials

for making new
challenging
sensor
systems
.


In the present project proposal,
a certain part of the
AISHA I and AISHA II
consortia
(SHM
-
WHO

proj ects i n the 6
th

and 7
th

Frame Programmes) has been
complemented
by new partners creating a
complete chain of expertise
, including all “technical stakeholders” pr
eVen琠in 瑨e value cUain of aircraf琠
浡in瑥nanceH repair anT overUaul (MRO).
T
Ue conVor瑩u洠
of PA䍉S
iV convinceT 瑨a琠瑨e propoVeT
working plan will enable all projec琠par瑮erV 瑯 crea瑥 enor浯uV VynergiV瑩c effec瑳 con瑩nuing 瑨e
V瑲a瑥gy
i浰le浥n瑩ng

M VyV瑥浳 in opera瑩onal airlinerV wi瑨in 瑨e Vcope of a Nuropean projec琮



TUiV
PA䍉S
a
pproacU requireV focuVeT reVearcU anT i浰le浥n瑡瑩on effor琠 uVing
well
-
FRAME
coordinated collaborations

of
many disciplines and expertise in Europe
. The
European
Research Area

establishes the ideal platform for such a collaborative undertaking, and the considerable financial risks
can perfectly be reduced by a great amount by appropriate funding from dedicated European research
programmes. In this sense, the enhanc
ement of the competitiveness of European aviation industry is
the final target of this project, and it is considered as a strategic advantage that the
PACIS
proposal has
been endorsed by the
European Aeronautical Science Network (
EASN).





Theme

7:

TRANSPORT

(including

AERONAUTICS)



Call

identifier:

FP7
-
(AAT)
-
2012
-
RTD
-
1


11

1: Scientific
and/or technical quality, relevant to the topics addressed
by the call

1.0 Introduction


In every civilisation,
excellent transport

systems are required to ensure economic and social welfare.
This holds, e.g., for the Roman road network, the Silk Road, the

English
, Spanish
and Dutch seafaring
,

nowadays
container traffic and pipeline systems as well as
all
branches

of aviation
. To ensure faultless
transport of human beings and goods, efficient

maintenance

and
repair

of such transport systems have
decided and will decide over the success of any economic system. Nowadays,
reliability

aspects

of
transport systems are frequently based on regular, i.e. scheduled inspection

cycles. Ho
wever, it is
envisaged that the
large cost

associated with this approach can be avoided by a condition
-
based
maintenance

schedule.

1.0.1 Why structural health monitoring?


“Structural health monitoring”

(SHM) stands in many cases for t
echnologies using permanently
attached sensor networks to enable continuous inspection

of structural integrity. In the last two
decades there has been an exponentially growing interest in structural health monitoring systems for
differen
t kinds of aircraft
[1, 2]
. Beside the expected enhancement of
safety

and
maintenance

performance
, especially
economic

aspects play an important role. This regards on the one hand the
reduction of inspection
costs and on the other hand, the possible weight reduction

of aircraft parts at
the designing phase of an aircraft. The main benefits of SHM are given in
Table
2
.


Achievement of

cost
savings

by reduction of
inspection

costs and repair
resources, and the possibility to
reduce material weight at the
design phase.

Enhancement of
operational
safety

by more
frequently applied inspections
and enhancement of the
detection probability.

Greening of air transport

by reducing replacements of
components and weight
reductions leading to fuel
reduction, as well as avoidance o
f
contamination by toxic fumes.

Table
2

Main benefits of Structural Health Monitoring


The routine
implementation

of structural health monitoring in aircraft is only a question of time. The
later
-
described obstacles, preventing implementation of SHM systems, can be avoided by a dedicated
implementation strategy mentioned below. Moreover, end
-
users
,
such as operators (airlines
),
maintenance provider and authorities must be convinced that complete
airworthiness
is

ensured
. The
present project wants to provide an essential contribution to this objective. The develo
pment of an
effective structural health monitoring system must be finally integrated into a structural
health
management system

where the data on structural integrity are classified and where procedures of
maintenance

and allocation of
resources are organised (see also the TATEM

project, FP6 502909).


It is thus compulsory that the developments achieved within the project meet the airworthiness
requirements and fulfil all aeronautic standards from the very beginning. With t
his objective in mind, a
specification sheet including
airworthiness requirements

as well as adaptation to standards has to be
created before the initial definition of sensors to be applied for the different SHM methods and
technologies in function of its
applications.


Theme

7:

TRANSPORT

(including

AERONAUTICS)



Call

identifier:

FP7
-
(AAT)
-
2012
-
RTD
-
1


12

1.0.2. The SHM
sensors

and systems
to be developed

by
PACIS
at a glance


PERCOLATION ELECTRO
-
CONDUCTIVITY MONITORING
: Fine
-
grained conducting particles embedded in
electrically insulating matrices can build up conducting
composites when the particles are connected by a
percolation network (
Figure
1
).
P
ercolation conductivity will
however vanish
if those composites come in contact with
dedicated
solvent
s
. This
break
-
down

enables
senso
rs for
detecting harmful liquids (water, kerosene, hydraulic
liquids, mineral oil).
Further

applications
lead to
painted
percolation gauges monitoring fatigue cracks and corrosion.
All sensors use the collapse of percolation conductivity that
ranges
orders

of magnitudes

above

baseline variations
[3]
.


OPTICAL MONITORING:

Optic
s
plays

frequently
a role
in
aircraft

maintenance
, such as
most basically
for visual
inspections. For
PACIS
, a substantial enhancement of the
probability of detection for visual and camera inspection
(using polarisers)
of damages will be achieved by using
polarising coatings

attached to the outer skin of composite
materials and traditional aluminium fuselage pa
nels. A
second concept is based on
micro
-
structured polymer
optical fibres

providing an alternative tool for detecting
liquids and fatigue cracks. This is achieved by a break
-
down
of light propagation
in
polymer optical fibres due to the
fare
-
going damage
of the w
ave
-
guiding core that is
to be developed
within the project.


ULTRASONIC MONITORING:
Lamb

waves (
Figure
3
)
are guided acoustic waves propagating in plate
-
like
structures typical for aircraft components, and they
are disturbed by cracks,
delamination

or loose
connections, resulting in scattering including mode
conversions
[4, 5]
. This is monitored with temporal
and amplitude resolution in reflection or transmission
and with two dimensional resolution by array
techniques. Furthermore, the elasto
-
acoustic effect
allows monitoring of the actual load an
d due to
thermal expansion also of the actual temperature. Appl
ications involving compact high
-
load parts and
smart components are additionally based on monitoring of the transport properties of surface acoustic
waves (SAW) and bulk acoustic waves.


ELECTROCHEMICAL MONITORING

(
Figure
4
) of
corrosion is based on processes related to the
dissolution of metals or other conductive materials
like carbon and the formation of oxides and other
products at the surfaces. Monitored are also
degrading bar
rier properties of protective
coatings. Detailed knowledge on chemical
conditions is gained by impedance spectroscopy,
which leads to a highly characteristic multi
-
contrast monitoring scheme since characteristic
relaxation processes contribute substantiall
y to the
observed spectroscopic contrast.



a) b)

Figure
1

Scheme of percolation conductivity and
installation of
a prototype
percolation sensor in
the
forward galley of a Boeing 737
-
500.



Figure
2

Improvement of visual inspections of e.g.
barely visible im
pact damage by using polarising
coatings demonstrated at a Euro
copter CFRP
sandwich composite.



a) b)

Figure
3

a) Interaction of a Lamb

wave with an artificial notch
reflection and
b) attenuated transmission array installed in
helicopter tail boom Mil 8.







Figure
4

Typical response of damage of seat tracks/floor beams
with electrochemical impedance using electrochemical sensors.

Theme

7:

TRANSPORT

(including

AERONAUTICS)



Call

identifier:

FP7
-
(AAT)
-
2012
-
RTD
-
1


13

1.0.3 Why
PACIS
needs public funding

within
the frame of
a

European project
?

The

encouraging

experience
from previous projects
of
successfully
implementing

SHM systems at
TRL
4

in
operational airliners

(AISHAII)

create
s

enormous opportunities when applied
to

new challenging
SHM
technology

that will be

developed
by
the
PACIS
consortium
.

However, t
he risks inherent to this
approach cannot be funded by the budgets of the participating partners

alone
, and the risk/pro
fit
balance
thus
requires
and encourages
support by funding
bodies of
the European Research Area.

The
Aircraft Integrated Structural Health Assessmen
t project (
AISHA
-
EU
-
FP6, STREP 502907, 2004
-
2007)
addressed
basic aspects

of damage detection in aircraft
using
ultrasonic Lamb waves

for different
materials, structures, damages and environmental conditions. Despite of the achievements obtained, a
number of challenges remained concerning
signal interpretation

and

durable

sensor connections
.





B737
-
530
-

D
-
ABIX (sensors
implemented in April 2011).


B747
-
430
-

D
-
ABVX (sensors
implemented in October 2011).

B747
-
430
-

D
-
ABVM (sensors
implemented in November 2011).

Figure
5

The “AISHA
II
fleet” with percolation sensors providing
continuous data on the structural health of floor structures.


The AISHA II project (EU
-
FP7, CP 212912, 2008
-
2011) achieved an upscaling
of the consortium and the
participation of a maintenance provider (Lufthansa
-
Technik) offered
first
access to
realistic
implementation areas
.

W
ithin the project, it was possible to
implement at

TRL
4

[6]

into
three
operational airliners
(
Figure
5
)
,

and
the results obtained were so convincing that
it was even possible
to
adapt maintenance procedures for floor structures in
the
Boeing 737 fleet.
Meanwhile, at the
International Workshop of
Structural Health

Monitoring at the University of Stanford (IWSHM, 13
-
15
September 2011), the demonstration of the floor structures sensor was honoured (
Figure
6
) with

the
“Most practical SHM application in aerospace award” (sponsored by AIRBUS).





Figure
6

Floor structure sensor
at the
International Workshop of Structural Health Monitoring at the University of Stanford (September
2011), winning demonstration and award ceremony in Palo Alto (CA) with Dr. Helge Pfeiffer (left) and Holger Speckmann (AIRBUS
, right).


AISHA II was also a success for the funding
policy of the European Commission w
ithin the FP7
programme, and the Directorate General for
Research Transport/Aeronautics has decided to
highlight AISHA II sensors to illustrate the EU
funding policy to a wider audience, e.g. a

video

was produced on the occasion of the EC
-
organised
Aeroday
s 2011

in Madrid where finally
just 3 of all recently funded European projects in
aeronautics were selecte
d. The following figure
gives an
overview on the
media

response that
AISHA II has attracted in the past year (
Figure
7
).


Figure
7

Echo of the AISHA II project in diverse media
[6
-
11]
.

Theme

7:

TRANSPORT

(including

AERONAUTICS)



Call

identifier:

FP7
-
(AAT)
-
2012
-
RTD
-
1


14






Figure
8

“TAKING OFF TO THE FUTURE”
-

DVD produced by the European Commission on innovation in aeronautics with extensively reporting
on the AISHA II project
-

first presented at the plenary session of the Aerodays 2011 "TAKING OFF TO THE FUTURE
-

EU
-
funded resear
ch for
greener, safer and smarter aviation"
-

http://sirius.mtm.kuleuven.be/Research/AISHA
-
II/video.html
.


PACIS
is copying
parts of
the strategy
of AISHA II
of bringing
new
sensors
at TR
L

4…6

in
to

an operational
airliner
,

and an
essential
point of
PACIS

is
thus
the extended participation of maintenance providers
belonging to leading

European airlines

and alliances. This is important because the addressed topics in
the respective FP7 call refer explicitly to maintenance
(
AAT.2013.4
-
4. Maintenance, repair a
nd disposal
)
.


The following table clearly indicates the potential impact of
PACIS

with respect to the participating
partners
, note that in Europe, approximately 5000 commercial aircraft are in
-
service
[12]
. Within
PACIS

there would be a principal access to 27 % of the European fleet.


MAINTENANCE PROVIDER i n PACIS

AIRCRAFTS

PARTNER/SUBSIDIARIES

SUM

ALLIANCES

Lufthansa Techni k AG

368

352 (Di verse)

720

STAR ALLI ANCE

I beri a
-

Mai ntenance and
engi neeri ng

106

146 (Bri ti sh
Ai rways)

252

ONE WORLD

KLM
-

Mai ntenance and engi neeri ng

118

253 (Ai r France)

371

SKYTEAM & NW /
KLM


592

751

1343


Table
3

Maintenance providers within the
PACIS

project and their relationship with the European aircraft fleet

1.1 Concept and objectives of
PACIS

The focus lies on the implementation
and testing
of
the the PACIS developed sensors
as minor changes
(p.
6
) in
the
aircraft

to

reach TRL6
; this enables fine
-
tuning of
the SHM
systems before upscaling
to
higher TRL,
e.g.
with extended data logging facilities. Moreover, the solutions proposed are purely
generic so implementation in different kind of aircraft is possible.




Airbus A380 (
ASCO,
CFRP
hinge arm, slat
-
track)

Airbus A340 (
IBERIA,
aluminium
floor
structure)

Airbus A320 (
ASCO,
maraging steel
-
slat
track)







Boeing 747
-
400 (
Lufthansa Technik
aluminium
floor structure, avionics bay)

Boeing 737
-
500 (
Lufthansa Technik,
floor
structure,
Al 2024
-
T3
fuselage)


McDonnell Douglas 11 (
KLM,
floor structure,
Al 2024
-
T3
fuselage)




Mil 8 (
RTU,
Al 2024
-
T3 tailboom)

EC 135 (
Eurocopter,
CFRP tailboom)



Figure
9

Aircraft types addressed
and possible installation targets
within
PACIS.

Theme

7:

TRANSPORT

(including

AERONAUTICS)



Call

identifier:

FP7
-
(AAT)
-
2012
-
RTD
-
1


15

1.1.1
Pre
-
s
elected
targets

for PACIS
in operational aircraft or realistic full
-
scale parts

I
nstallation targets
selected

for the intended SHM technologies

are presented
.
We focussed

on
a
balanced mixture

between installation targets provided by maintenance providers (Lufthansa
-
Technik,
Iberia, KLM) and manufacturers (ASCO

Industries
). Moreover, there is an informal agreement with
Eurocopter
Marseille
(EADS) to bring the
PACIS

consort
ium in contact with
customers

for a possible
implementation of
sensor
s

in operational helicopters
enabling
fine
-
tuning
of
sensor systems

that has
reached TRL6
.

In this way, PACIS is more focussing on retrofit than in
-
production implementation of
SHM. Howev
er, this is not a limitation for the latter case.

Different materials, such as aluminium alloy, maraging steel,
CFRP
composite will be included, and it
has to be emphasised that despite of the growing market for
composites
,
more
traditional materials
such
as
aluminium

alloys will remain important in aircraft industry for many years. Furthermore,
different aircraft types (airplane, helicopter) are addressed (
Figure
9
) proving that
PACIS

really intends
to provide
generic solutions

for
really
realistic environments. Moreover, due to the close relationship
with industrial partners
, estimati
ons on
economic benefits

of the proposed systems are possible.


PACIS TARGET

FUSELAGE,

HINGE ARM AND
SLAT TRACK

PRONE TO

FATIGUE/
OVERLOAD DAMAGE


On July 13, 2009, during flight SW2294 from Southwest Airlines (
Figure
10

a), a
crack within
the fuselage
of a Boeing 737
-
300
became fatal

and passengers could even notice a “ripped” fuselage from the cabin.
The reason was a fatigue
damage
in the aluminium al
loy sheets, more specifically at the so
-
called chemical
milled steps (
Figure
10

c).

Chemical milled
steps arise from material removal
by
chemical etch
ing that is originally intended to
achieve weight savings. Due to stress concentration at the respective parts, cracks develop (
Figure
10

d),
and since

that incident, airlines are required to perform additional costly checks on diverse Boeing 737
types
[13]
, an ana
logous incident occurred two years later (see
Figure
10
, b). Cracks in chemical milled
steps
were

also reported for other aircraft types such as in the forward skin area of Avro Jets RJ 85.

PACIS will
therefore address these
imple
mentation areas.
Similar fatigue problems
occur in other parts, such
as
pylon ribs. In slat tracks
and hinge arms, also full
-
scale parts within the
project proposal, cracks
are not reported in
operations so far. On the
other hand, those
components are rela
tively
heavy and after weight
savings and extended
damage tolerant
principles, health monitoring would an interesting option respond to the higher probability of crack
formation.
For the A380 hinge arm, introduction of composite material is scheduled for t
he next 5 years
according to AIRBUS planning. SHM systems for fatigue delamination offer interesting options (
Figure
10
d).


PACIS TARGET

HIGH PRESSURE TUBES
IN A/C
DEVELOPPING

FATIGUE CRACKS


In November 2009, a leak in the hydraulic system of the spoiler of an AVRO Jet RJ 100 of Brussels Airlines
(OO
-
DWK) at Brussels/Zaventem airport caused an injury of 4 passengers. The incident
during la
nding
was
most probably caused by fatigue damage of hydraulic pipes after cyclic pressurisation during airline
operations. Another example is the incident at flight QF32 (4 November 2010) with a Rolls
-
Royce jet
engine of an Airbus A380 of Quantas (Figure 9
a) that provided immediately a good example of the need of
a monitoring systems system. Vapours of leaked mineral oils caused an explosion within the jet propulsion
system; an early alert would most probably have prevented such a dangerous incident.


Figure
10

a) bended panels in a Boeing 737 due to chemical milled pockets, b) Damaged panels from
Southwest flight 2294 (13 July 2009), c) Airbus A380 hinge arm and d) fatigue delamination in
respective composite material
.

Theme

7:

TRANSPORT

(including

AERONAUTICS)



Call

identifier:

FP7
-
(AAT)
-
2012
-
RTD
-
1


16

Early
prototypes of percolation sensor have shown interesting performance for monitoring the
occurrence

of leakage enabling early repair before fatal accidents will happen.

a)

b) I
c)

d)


Figure
11

a) Damaged hydraulic tube from Brussels Airlines incident with an AVRO Jet RJ 100) b) Spoiler area Airbus A340 known for
hydraulic liquid leakage c) Damaged Rolls
-
Royce jet engine of an Airbus A380 of Quantas d) Part of the mineral oil tube that was damag
ed
.


PACIS TARGET


FLOOR
STRUCTURES

ATTACKED BY
CORROSIVE LIQUIDS


In aircraft, aqueous liquids arising from spillage, condensation or rain can result in heavy corrosion of
structural parts (
Figure
12

and
Figure
13
).
The respective topic (AAT.2012.3.4
-
2. MAINTENANCE) is also
dedicated to corrosion pre
vention. Besides the improvement of coating and sealing systems,
information on the presence of corrosive liquids is a complimentary option for achieving corrosion
prevention. Even for the case that the fluid cannot be removed immediately; information on w
etness is
a big added value to maintenance teams for allocation of manpower for repair and to skip scheduled
sealing inspections finally
.





Figure
12

TOP: Repaired and replaced seat tracks + floor beams in an A340
-
600 (marked areas in operational document from MRO) and
BOTTOM: seating plan showing that
this kind of corrosio
is limited to liquid exposed areas, such as galley and lavatory
.


Wetness is u
navoidable in areas exposed to water and hi
gh
humidity
, such as drainage channels or at
the inner skin of the fuselage where temperatures are in the range of minus 60°C during flight

(
condensation
)
. In
some areas
however, wetness has to be avoided and rele
vant hot
-
spots can be found
in floor structures under galleys and lavatories (
Figure
12
)

as well as
in
the
avionics

bay
. A specific
challenge is the rear galley of the

MD 11 where inclination of that aircraft type during normal flight leads
to additional accumulation of water (
Figure
13

b). Also cargo airplanes suffer from water ingress causing
corrosion in floor structures and potential short
-
circuits in electrical systems (
Figure
13
, c and d).


a)

b)

c)

d)



Figure
13

a) Heavily corroded seat track and floor beam in a A340
-
600 due to corrosive liquids b) Rear galley of MD 11 heavily exposed to
water ingr
ess in floor structures c) Floor structure in B747 cargo aircraft d) Avionics bay B747 exposed to water ingress in cargo vari
ants
.


Theme

7:

TRANSPORT

(including

AERONAUTICS)



Call

identifier:

FP7
-
(AAT)
-
2012
-
RTD
-
1


17

PACIS TARGET

FLOOR
BEAMS/
SEAT TRACKS
AND BULKHEADS
DEVELOPPING

CORROSION


Detection of corrosive liquids is not always an

option when presence of water is unavoidable, in those
cases
,

corrosion monitoring
is in place to provide information for
MRO operations. The floor structure in
aircraft is subjected to unpredictable corrosion if leaking liquids from the galley or moistur
e from
incoming passengers affect these structural elements. In the case of moderate corrosion, beams can be
grinded and sealed with new anticorrosive coating. However, if the beam is stronger corroded (usually
more than 10% of thickness), the whole beam h
as to be replaced. The only chance for det
ection are at
the moment the D
-
checks (interval app. 4 years, sometimes also C
-
checks are an option), but these
intervals are too long in many cases. It is therefore important to identify early stages of corrosion
to
prevent very expensive replacements. An appropriate monitoring system would be the optimal solution.


a)


b)

c)
d)


Figure
14

a) Moderate damage on floor beams of AVRO Jet RJ 100 close to the flight deck, partially grinded b) Bulkhead of a Boeing 747
separating pressurised and non
-
pressurised fuselage c) Hot
-
spot of corrosion close to drain holes in lower part of bulkheads d) Sp
oiler area
prone to stress corrosion in spoiler bay beams
.

In addition to floor structures,
PACIS

address
es

further “hot spot
s
” where corrosion is the predominant
degradation mechanism
such as

the vicinity of drain holes in the bulkheads (Figure 14c) and
spoiler
areas in the wing (Figure 14d) which are prone to coating degradation followed by corrosion underneath
it and stress corrosion cracking respectively.


PACIS TARGET


ALUM䥎䥕M
ALLOY
AND COM偏S䥔E
FUSELAGE
EX偏SED


䥍偁CT
DAMAG
E


A special attention is given to the improvement of the
detection
of
mechanical
impact
finally
leading to
cracks
(aluminium alloys)
a
nd delamination (composite). This is usually cause
d

by
vehicles at airports,
bird

strike
,
mishandling of maintenance tools

a
s well as

overload. I
n
PACIS
, new ideas will be
implemented combining indicative SHM with traditional advanced NDT. Severe damage almost invisible
to the naked eye in many cases, can lead to fatal failure within a short period of time (barely visible
impac
t damage, BVID).

a)

b)

c)

Figure
15

a) Impact damage in leading edge of A320 b) Impacts indicated in aluminium fuselage of B737
-
500 c) Barely visible lightning strike
and current visual inspection scheme
.


Furthermore
,

the detection of lightning strikes at the fuselage and wing areas is a challenge for visual
inspection. The inspection process accumulates up to 16 hours per aircraft inspection leading to about
10 hours unplanned downtime. Therefore the investigation of
improved inspection methods is essential.
In this context, e.g. the separation of ordinarily paint defects from small lightning strike damage is a
main challenge for economical detection technologies.

1.1.2
PACIS concept
of implementation

Such as mentioned

previously, SHM methods used for damage detection within
PACIS

will be the
electrical
percolation effect, optical methods, guided ultrasonic waves and electrochemical monitoring.
However, appropriate
implementation strategies

are as important as technolog
ical maturity. The
following main concepts are presented. Their
balanced combination

will help setting substantial steps
ahead to reach the objectives of the respective FP7

call
FP7
-
AAT
-
2013
-
RTD
-
1.

The following
key
-
elements

are proposed:



Theme

7:

TRANSPORT

(including

AERONAUTICS)



Call

identifier:

FP7
-
(AAT)
-
2012
-
RTD
-
1


18

A)
LOW IMPLEMENTATION THRESHOLDS



Avoid changing maintenance
procedures;

give rather added value to insufficient existing
procedures (such as the long maintenance interval (D
-
check) for aluminium alloy
-
based floor
structures).



Avoid on
-
board electronics in the

initial phase; only use passive sensors that are inactive during
flight.



For sensor systems, u
se existing certified components, or new components with a very low
certification threshold.

B) REALISTIC IMPLEMENTATION AREA



Focus on realistic hot
-
spots (floor

structures,
bulk head,
slat tracks)


screening of large areas is
too ambitious for the current generation of SHM (the skin area of a fuselage of an Airbus A340 is
about 500

m
2
).



Avoid SHM
in
areas where
traditional
NDT inspections
on other parts are
unavoidable.

C) LOW COST



Use modular approaches, i.e. make use of existing components that are already available in the
“hangar”.



Invest essential resources to search for
straightforward

and robust solutions rather than in over
-
complicated, sophisticated s
olutions
.

D) SYNERGY OF SHM WITH TRADITION
A
L NDT AND REPAIR



Use “indicative SHM” avoiding complete defect
sizing

with SHM, use SHM as alarm systems
instead triggering further investigation with NDT
.



Offer SHM sensors that also enable immediate repair or s
imilar kinds of problem solving (e.g.
drying floor structures)
.


In this context, it is also interesting to have a look at the
possible

different scopes

of selected
stakeholders on SHM.


.
AIRLINES

AND

MAINTENANCE

PROVIDERS
.

Various SHM solutions popular in academia are still causing
sceptic responses “in the hangar” because
they are mostly
based on laboratory systems that hardly
work under operational conditions. In this context, the usual absence of maintenance experts at
i
nternational SHM conferences is striking and illustrates the gap between a SHM introduction and the
expectations of maintenance
departments working under commercial restrictions
.



Our response
is

proposing solutions that are based on the
key
-
elements
A)
-
D)

under point 2.


.
MANUFACTURERS
.

Many Original Equipment Manufacturers (OEM’s) consider SHM as key innovation
and sales argument since many years
[2]
, i.e. extended research programmes are performed and
solut
ions are promised for the upcoming years. But except of the technical and administrative obstacles,
there are at least two issues that must be considered. A) The customers might complain why OEM not
just making the materials better instead of providing new

sensor systems that costs and additional
maintenance, i.e. SHM should
not compensate
for

inadequate or failing materials
. B) SHM should also
support airlines to avoid
unnecessary replacements

of parts that are replaced on a scheduled basis.
SHM could even
tually reduce the global overall
-
turnover for respective parts, and this means OEM’s
would
cannibalise

own products by introducing SHM. On the other hand, an OEM must give customers
the possibility to perform maintenance in an optimised way.



Our response

i
s
i
ntroducing
SHM via
maintenance providers and OEM

in parallel, taking
advantage of the respective different scopes.


.
AUTHORITIES
.

Maintenance is normally a very “conservative” business due to the extraordinary high
safety requirements. Also with the new

developments of Airbus A380 and Boeing787, one
has
realised
that new developments need time and innovation also can bring economical risks.



Our response

is to start implementing SHM as
minor changes
(p.
6
)

of structural parts or of the
avionics.

Theme

7:

TRANSPORT

(including

AERONAUTICS)



Call

identifier:

FP7
-
(AAT)
-
2012
-
RTD
-
1


19

1.1.3 Relevance of S&T objectives with respect to the call


In
the modern society
, not only efficiency
and
safety
play an important role to assess the quality
of a specific transport system, but also
environmental

and
ethic

aspects are more and
more important. Therefore, the European
transport policy also focuses on the development
of integrated, safer, “greener” and
“smarter” pan
-
transport systems. In this context, it is of
high

importance that those developments are for the
benefit of all citizens, the environment
, the
“airport neighbours”,

as well as natural resources
must
also
be
considered
. The further development

of Europe

as an
economic

and
cultural

entity thus
requires very efficient, affordable and compatible transport systems. An important issue is the balance
between different kinds of transport systems, such as railways, aircraft, seafaring or

road network
(intermodality). Also this balance must
consider
environmental, safety and economic aspects.

At the moment, the air traffic

worldwide increases with
5%
per year (related to the number of
passengers) and this means that at 2020, there will be a threefold of air traffic compared to the
beginning of the millennium. Moreover, whereas in 2008, approximately 20.000 commercial airplanes
were in service (AIRBUS,
Boeing, Embraer, Bombardier) the additional market demand is estimated to
grow by 16.000 new aircraft!! for replacing old aircrafts and responding to the additional requirements
due to the enhanced number of passengers
[12]
.


To respond to these challenges, the
Advisory Council for Aeronautics Research in Europe

(ACARE
) was
established
in 2001 as a multinational initiative. They have finally formulated the so called “
vision 2020

guiding the main objectives of the European and national transport policy with a focus for the year
2020. The main challenges of this ambitious programme are
[14]
:



More affordable, safer, cleaner and quieter air transport system

o

Quality and affordability

o

Substantial reduction in travel charges

o

Time spent in airports (15 to 30 min, max) delays (99
% of all
flights within 15 minutes)

o

Environmental impact minimised (Halve noise, reduce CO
2

by 50% and NO
x

by 80%)

o

Five
-
fold reduction of accident

rate

o

Time to market halved



Improved Security



Education policies to provide essential future
skills



Better value from European Research Expenditure


Structural Health Monitoring

will contribute to the objectives of
ACARE
in three different ways. In the
introduction section, the three main benefits of SHM were already mentioned (cost savings
,
enhancement of safety and improvement of maintenance

performance, ensuring high passenger
throughput). In the 7
th

frame programme
, all of these
ACARE
aspects are addressed within t
he call
FP7
-
AAT
-
2013
-
RTD
-
1
.

It still has to be mentioned that the Vision 2020 will be followed
-
up

by
pathway 2050

where ACARE is setting
further
priorities at the moment. Consider the life cycle and development time
for a new generation of aircraft, such p
eriods must be considered already today.




Theme

7:

TRANSPORT

(including

AERONAUTICS)



Call

identifier:

FP7
-
(AAT)
-
2012
-
RTD
-
1


20

Challenge 3:
COMPETITIVENESS THROUGH INNOVATION.

A
ctivity
7.1.4
IMPROVING COST EFFICIENCY

1)
AAT.2013.4
-
4

M
aintenance, repair and disposal


Challenge 1: ECO
-
INNOVATION

A
ctivity
7.
1.1 THE GREENING OF AIR TRANSPORT

2
)
AAT.2013.1.1
-
2
A
erostructures


COST EFFICIENCY



Cost savings

by
SHM concern direct and indirect costs. On the one hand,
direct costs

for traditional
inspections and early replacements of very expensive structural parts can be
avoided
. On the other
hand,
indirect costs

arising from downtime can be
reduced
. It was estimated that the potential of
reducing inspection

time (not cost) is in the range of 45%
[11]

with respect to the structural inspections
representing 7% of the tot
al inspection time. Another aspect regards the possibility of the prolonging of
the integral service time for aging aircraft.

An additional interesting cost saving

aspect regards the
design

of
new aircraft
. If there is a
possibility to
monitor structural health almost continuously, the amount of materials used for structural
parts can be
reduced

which can have an additional positive impact concerning weight and long
-
term
performance. The reductions will influence the reduction of fuel co
nsumption and the production cost
when using cheaper materials. The reduction of fuel consumption will even contribute to greener air
transport. An overview on the possible cost saving

effects is given in the following diagram (
Figure
16
):


a

Figure
16

Potential cost saving

effects by implementing SHM
.


As stated above, SHM can lead to a reduction of
operational and production costs. As of now, aircraft
inspection

is performed on a fixed regular time line, during aircraft downtime and using classic NDT

techniques (ultrasonics, radiography, eddy current, visual inspection,

boroscopic inspection, etc). Some
disadvantages associated with

this strategy are well known:

Theme

7:

TRANSPORT

(including

AERONAUTICS)



Call

identifier:

FP7
-
(AAT)
-
2012
-
RTD
-
1


21



Classic NDT
inspection

can be

extremely

time
-
consuming
(the inspection of a few square
meters of the forward skin fuselage area of AVRO RJ85 takes about one
week),

but the detection
of faults is nevertheless extremely seldom.



Classic NDT

techniques sometimes require
dismantling

of aircraft facings to access the
structural parts to be investigated enhancing the downtime

period.



Using
a scheduled based inspection

strategy, there is no knowledge about the damage state
before the inspection

is carried out; this inevitably also leads to attention being devoted to
parts of the aircraft structure which are still in good co
ndition.



Each day of
downtime

results in a loss of income (turnover), which has been estimated at
maximum 150.000 € a day (for wide body aircraft).


The introduction of
structural health monitoring

will enable optimised allocation of resour
ces for
inspection

and maintenance

that will result in:



Longer time periods

between aircraft downtimes, downtimes has only to be planned when a
critical size of damage has really formed.



Shorter downtime

“in the hanga
r” because the nature of damage is already known before the
aircraft is taken out of service.



A more
efficient operation

and a
reduction

in inspection

and maintenance

costs


It is
difficult

to give an
exact prediction

on cost savings to be achieved by structural health monitoring.
The reasons are on the one hand the different cost models applied by different
a
irlines and in different
countries (ATA vs. EU). Furthermore, due to the exploding kerosene and oil prices, the

fraction of the
costs related to maintenance decreases proportionally. A systematic cost model (
Figure
17
) for aircraft
can be defined using the
life cycle cost
(LCC
)
.
It

comprises all costs required during the whole lifetime of
an airplane, thus including purchase costs, direct (DOC) and indirect operating costs (IOC) and disposal
costs, if appropriate.


Figure
17

Simplified cost model for an aircraft according to the life cycle costing (LCC
-
according to customers view). The numbers are rough
estimates derived from different sources, (TOC
-
total operating cost, IOC
-
indirect operating cost, DOC
-
Direct operating cost)

and vary with the
type of aircraft, the current oil price, the cost model applied, etc. Disposal costs are not considered.


A frequently used comparative element to evaluate the efficiency of
a
irlines is the direct operating cost

(DOC). Therefore, the fo
llowing considerations will be related to this key performance parameter. The
potential for structural health monitoring can be situated in the reduction of costs within the BASE
maintenance, because Line and Light maintenance costs will barely change due
to SHM. If the half of the
inspection costs for structural parts within BASE maintenance is saved by structural health monitoring,
the effect on the direct operating cost can be derived according to the following estimation. Consider
100.00 € spent for dir
ect operating cost. Then 11.00 € is spent for maintenance. This means that about
6.00 € must be reserved for BASE maintenance. If about 10% of the BASE maintenance is dedicated to
structural components, those costs would correspond to about 0.60 €. If the
half of this amount can be
Theme

7:

TRANSPORT

(including

AERONAUTICS)



Call

identifier:

FP7
-
(AAT)
-
2012
-
RTD
-
1


22

saved by SHM, there will be saving of about 0.30 € with respect to 100.00 € of direct operating costs.
This appears to be a small effe
ct, but on the other hand, the a
irline business is an extremely competitive
market where the sm
all profit margins are in the range of 1%. In that case, efficient SHM techniques can
contribute to
make the difference!

On the other hand, the introduction of SHM systems also requires investment and operating costs, and
the final balance must ensure that

essential net savings remain.


GREENING


In general, condition
-
based, unscheduled inspection and maintenance

would essentially reduce the
resources required in MRO operations.

o

In first instance the
avoidance

of
unnecessary

replacement

of aircraft parts and the use of
accompanying resources is concerned. Even for the case that replaced parts can be recycled,
energy and production costs are needed to enable replacements.

o

The last years, there is a growing discussion on
toxic fumes

in the
passenger’s cabin arising from
diverse hydraulic liquids and mineral oil based lubricants, even leading to incapacity to work for
pilots and flight attendants. The reason is spilled liquids entering the air
-
conditioning system of
the aircraft. However, the

early detection of leakage of mineral oil and hydraulic liquids was
already successfully shown by the recently developed percolation sensors in AISHA II, and it is to
expect that the above mentioned problem can essentially be reduced.


SAFETY


Aircraft s
afety depends on efficient means of damage detection. Though scheduled inspection

procedures have resulted in excellent safety records, there have in the past been a number of incidents
where extensive material damage has gone unnoticed and has resulted in major accidents:

o

Qantas Flight QF32 (4 November 2010)


Explosion

of
vaporised
mineral oil

arising from
leakage, in parallel, AISHA II
had developed
a
TRL 3 proof of concept
that was available in March
201
0

o

On July 13, 2009, flight SW2294 from Southwest Airlines, a part of the fuselage of a Boeing 737
-
300 was damaged due to
cracks in

chem.
-
milled steps

o

In November 2009,
leakage of hydraulic liquid

of an AVRO Jet RJ 100 of Brussels Airlines (OO
-
DWK) injury of 4 passengers


Functioning SHM sensor for hydraulic liquid developed within
AISHA II

o

Adam Air Flight 574, 2007 Indications of
me
tal fatigue
-
induced structural failure

o

Chalk's Ocean Airways Flight 101,
metal fatigue on the wing

o

Alaska Airlines, Flight 261, 2000: horizontal stabiliser failure due to
excessive wear

o

United Airlines, Flight 232, 1989: engine failure due to fan disk
fat
igue cracking

o

Japanese Airlines, Flight 123, 1985: rear bulkhead separated due to
decreased fatigue
resistance
following a faulty repair

o

Aloha Airlines, Flight 243, 1988: part of the upper fuselage separated during flight, caused by a
longitudinal crack

in

a
row of rivets

o

American Airlines, Flight 191, 1979: engine separation due to
cracking


The above, involving some of the most deadly accidents in history, are just some examples of airplane
crashes related to material damage, which could have been avoided

by continuous monitoring systems.
An early warning of impending failure could have been given to either flight or maintenance