Lufthansa Perspectives on Safe Composite Maintenance Practices

Transcription

Lufthansa Perspectives on Safe Composite Maintenance Practices
Lufthansa Perspectives on Safe Composite Maintenance
Practices
Experience with composite components
Damages on composite components
Damage detection
Repair processes and materials
Repair quality assurance
Total maintenance life cycle cost
Lufthansa perspectives
FAA Damage Tolerance and Maintenance Workshop
Amsterdam, May 9th – 11th, 2007
Page 2
% of Composite Structure related to total
Aircraft Structural Weight
B737X
50
B787
A350
A320X
40
30
A380 @
20
A320
10
0
1975
A340
A330
@ @
@
B777
A310
@
A310 B767
@
@ A300
B757
B737-300
1980
1985
1990
1995
Page 3
2000
2005
2010
2015
A310-200 /-300 composite materials application
A 310-200 without composite vertical tail
Page 4
A340-500 /-600 composite materials application
Page 5
After 24 years of operational, maintenance and repair
experience it can be concluded that:
4 Composite structural components will experience damages.
4 Damage detection requires specific skills.
4 Repair processes and materials are not standardized.
4 Repair quality is material and process dependent.
4 Difficult to asses quality of repair.
4 The total maintenance life cycle cost has not always proven
to be better than for comparable metallic structures.
Page 6
Practices
Damage detection
Page 7
Prevalent damages on composite structural components
can result from:
4 ground service vehicles
4 erosion
4 runway debris, tire separation
4 surface coating removal
4 bird strike
4 fluid contamination
4 lightning
4 design failures
4 hailstorm
4 manufacturing deficiencies
4 overheat
4 maintenance errors
Page 8
Total damages – Total fleet – Year 2006
Fleet Size:
243 a/c
Total damages: 1647 events
Repair Cost:
€ 33.200.000
Lightning Strike
216
Bird strike
184
1248
Mechanical impact
Page 9
Fuselage structural damages – Total fleet – Year 2006
Fleet Size:
Fuselage damages:
Repair Cost:
Lightning Strike
45
77
16
Bird Strike
Page 10
Mechanical impact
243 a/c
138 events
€ 3.500.000
Fuselage Structural damages – Total Fleet – Year 2006
Fleet size:
Wide body:
Narrow body:
99 a/c
144 a/c
Damage Frequency:
Wide body
Wide body: every 1000 flights
Narrow body: every 4600 flights
63
76
Narrow body
Page 11
Foreign Object Damage (FOD)
ground service vehicles
Page 12
Page 13
towing damage
Page 14
towing damage
Page 15
docking damage
Page 16
Passenger fly bridge
Page 17
Page 18
Reverser
translating sleeve
Page 19
Page 20
runway debris - damage on horizontal stabilizer
Page 21
tire separation
Parts of a tire or debris on the
runway may damage composite
structures heavily.
Page 22
bird strike
Bird strike results in heavy structural
damages. Affected areas are
radomes, engines and leading edges.
Page 23
bird strike
Page 24
Lightning
Lightning strike on
a CF6-80 translating
cowling
Composite materials are electric conductors.
Because of thermal overload and/or sparking,
adjacent fasteners have to be changed
after lightning damage.
Page 25
Lightning
Lightning strike on CFM56-5A
Fan Reverser
Page 26
Lightning
Page 27
hailstorm
Hailstorm damage often occurs on leading
edges, engine nose cowl and radome areas.
Hailstorm damage is
frequently more difficult
to detect on composite
structures.
Page 28
hailstorm
Page 29
Overheat
Fan cowl overheat damage
resulted from failed anti-ice
duct clamp
Page 30
Surface protection
Cracks in the surface protection
coat suggest structural damages
which could result in a premature
removal of the component.
Source of the cracks is not yet
completely identified, but can be
related to the excessive filler thickness
or to a change in the paint flexibility
by a chemical interaction with the
composite resin hardener.
Page 31
Surface protection
Page 32
Fluid contamination
water in an elevator
Water enters the elevator honeycomb
core through fastener holes due to
component „breathing“.
Repairs are difficult and time consuming.
Page 33
Fluid contamination
Fish is still
swimming !
General problem on many honeycomb sandwich components
Page 34
Manufacturing deficiencies
Surface treatment on honeycomb foil
leads to poor bonding properties
Page 35
Manufacturing deficiencies
Surface treatment on honeycomb foil leads to poor bonding properties
Page 36
Practices
Damage detection
Page 37
Damage detection
Many damages on composite structures are difficult to detect
visually and / or require special trained technicians and special
equipment to be detected.
4Fluid ingress on honeycomb sandwich components.
4Overheat on structures covered with heat insulation blankets.
x
x
x
BVID*
4Barely visible impact damages (BVID).
Compression strength after impact
4Lightning damage secondary effects.
x
x
x
x
Not visible
Visible on the
back surface
x
x
x
Visible on both faces
Impact energy
* BVID = Barely Visible Impact Damage
Page 38
Damage detection
Total damage on inner
side of structure
Visible damage on
outside surface
Page 39
Practices
Damage detection
Page 40
The repair of damages experienced in daily aircraft operation is
hindered by following peculiarities on the repair process and repair
material area:
4Process
¾ Standard repairs have only been developed for minor ,
“cosmetic” type damages.
¾ Lack of design information (material, lay up sequence, …) to assist in
new repair development.
¾ Missing of an agreed upon minimal substantiation criteria
acceptable to the authorities.
¾ Repair substantiation often requires full scale test articles.
¾ Repair quality very much process dependent.
¾ Special dedicated training required for maintenance and shop
composite repair personnel.
Page 41
4 Material
¾ Lack of material standardization, there is no worldwide official
identification system establishing the equivalence between two or several
materials.
¾ Perishable material with limited storage life.
¾ Availability in small quantities very difficult and often with long
lead times.
¾ Material for older products often not in production any more.
¾ Incoming material quality assurance inspection requires
extensive equipment and special skills.
Page 42
Practices
Damage detection
Page 43
The peculiarity of all bonded composite repairs is that the quality
strength wise of the of the bonded joint and the laminate build up can
not be measured without destroying the part. There is an equivalency
to the welding process and a similar industry standard as established
since many years for the welder qualification and process control
should be implemented for bonded and composite repairs, i.e.:
4 Dedicated training and qualification, including recurrent training
to maintain the skills.
4 Periodic showing of compliance with the acquired skills.
4 Process control coupon destructive testing.
4 Material control coupon destructive testing.
Page 44
Practices
Damage detection
Page 45
Aircraft
AircraftStructure
Structure
Maintenance
MaintenanceLife
LifeCycle
CycleCost
Cost
Recurring / Operating
Cost
Non Recurring Cost
Modification
Cost
Initial Spares
Provisioning Cost
Delta Fuel
Cost
due to:
Spares
Holding
Maintenance
Operational
Interruption
Temporary Spares
Weight
Unscheduled
Scheduled
Delay
Parts Lease
Modification kit:
Labor & Material
Cost
Drag
Evaluation
Overhaul
Removal
Reinstall
Inspection
In Flight
Turn Back
Cooling
Additional Training,
Tooling &
Documentation Cost
Disposal / Surplus
Cost
H.P.
extraction
LINE :
SCHEDULED :
SHOP :
Repair
on
Plane
Repair
on
Plane
Remove/
Reinstall
Repair
in Shop
Page 46
Overhaul
in Shop
Cancellation
Remove/
Reinstall
Diversion
Repair
in Shop
Down Time
Insurance
Economic Decision Tree
Repair
Tools
Spares
Maintenance
cost
UNKNOWN
INFORMATION
AVAILABLE
I
Design Task Group
INFORMATION
I
Recommendation
I
Range
I
I
Weight
Fuel
I
limit
burn
I
I
Cost of Implementation
Operating
I
(Acquisition cost)
cost
I______________________________
Cost
effective?
Yes
Page 47
No
Practices
Damage detection
Page 48
Damage prevention
Damage prevention activities
4 Campaign with mayor hubs,
Frankfurt and Munich for awareness
and damage reduction.
4 Flyer and Poster distribution.
4 Awareness sessions to highlight a/c
docking, towing and loading
procedures.
4 Information visits of airport
personnel at repair stations.
4 Main message: “it is better to pay
attention!”
Page 49
Training
Dedicated training for composite maintenance, repair and engineering
personnel.
4 Training courses for technicians, engineers and inspectors developed at
Lufthansa Technical Training using as guideline:
¾ CACRC training curricula (AIR 4938A, AIR 5278, AIR 5279)
¾ FAA / AMTAS / Edwards C.C. Teaching Points ( AIR 5719)
4 Additional engineering attendance at:
¾ Alteon Composite Repair course for engineers.
¾ Abaris Composite Repair course for engineers.
¾ Fraunhofer Institute / IFAM European Bonding Engineer
course.
Page 50
Quality assurance
Elaborated Quality Assurance concept to control process and material
quality (using AC145.6 as reference).
4 Process control:
¾ Traveler coupon implementation for each process step.
¾ Write-ups for temperature, pressure, vacuum parameters on each repair
step.
4 Material:
¾ Purchase from approved sources only.
¾ Conformity certificate inspection.
¾ Incoming material test to confirm certificate data.
¾ Controlled and monitored storage.
¾ Traveler coupon implementation for each material used in the repair.
Page 51
Non Destructive Inspection
Elaborated Quality Assurance concept to control process and material
quality. (cont.)
4 NDI
¾ Cooperation with Industry and Research Institutes to develop a new NDI
method to assess the bond-strength in the joint of composite structures.
¾ Investigation to implement existing NDI methods (shearography, lockin
thermography, ultrasonic excited lockin thermography etc.) in routine
maintenance for large area inspections.
lockin thermography
shearography
Page 52
Process and Facility Equipment
New Processes and Facility Equipment will be considered / introduced
for future repair capability
4 Process
¾ Cooperation with Industry and Research Institutes to develop a surface
preparation method providing more reliable adhesion properties on
bonded repairs on composite structures.
¾ Follow up on Selective Laser Coating Removal process.
4 Facility Equipment
¾ Larger autoclave.
¾ Laser coating removal equipment.
Page 53
New tools needed to optimize repair process for composites
Automatic cutting
of repair plies
Laser projection of repair
plies on damaged part
Laser paint
removal
Integrated
composite repair
design &
implementation
Composite repair design
ND Quality control
(Special CAD modules)
Shearography or Holography
Page 54
Conclusion
Summary:
4 Composite parts demonstrate significant benefits and are
established in commercial aircraft structures.
4 All composite parts will get damaged.
4 Durability, repairability and maintainability issues must be
addressed in the design phase and repairs for frequent damages
must be available at EIS.
4 Introduction of new a/c models with high percentage of composite
primary structure will require mayor efforts at airline and MRO
personnel training.
4 The composite industry has matured but is
still young.
Page 55
Questions ?
Page 56
Thank you for your attention.
Page 57

Lufthansa Perspectives on Safe Composite Maintenance Practices

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