Contemporary Challenges in Continuing Airworthiness and Maintenance Education and Training Mapping the Way Forward

Transcription

1 Contemporary Challenges in Continuing Airworthiness and Maintenance Education and Training Mapping the Way Forward Training and Certification Standards for Composite Maintenance & Repair Roland Chemama, GMI Aero President

2 Composite repair training and certification: Upgrading from operators technical ability to full composite repair process understanding

3 A350 Composite Materials overview (Source Airbus)

4 A350 Involving large structural parts... (Source Airbus)

5 Training and Certification Standards for Composite Maintenance & Repair Trends in increase of No of aircraft (Source Airbus)

6 Training and Certification Standards for Composite Maintenance & Repair Increase of volume of Composites per aircraft Increase of complexity of Composite parts

7 GMI Aero: An SME that developped since 30 years through internal R&D and Collaborative Research to become a leader for : Fabrication of Composite Structures Heating Systems, Process Models, Advanced Sensors, & Control Maintenance of Advanced Composite Structures Advanced Bonding, NDT, Surface treatment, Consultancy & Training Worldwide On Job Training, Training Centres in Paris and Montreal

8 Range of Agents, Customers and Partners Maintenance Equipment Contracts: - Airbus, Boeing, Dassault, Eurocopter, Bombardier, Embraer Aircraft Manufacturers: - EADS, Dassault, ATR, Airbus, British Aerospace, Dassault Aviation, Hurel Hispano-Snecma, Alenia, Bell Helicopters, Eurocopter, Airmacchi, Israel Aircraft Industries, BF-Goodrich, Latecoere, Saab, Hellenic Aerospace Industry, Singapore Technologies, Boeing Australia, Bombardier, Hafei China... Airlines & MROs : - Air France, K L M, Sogerma, Armée De L'Air, Marine Nationale, TAP, LAB-TAT, S A S, Alitalia, Ram, Tunis Air, Air Algerie, Air Canada, Iberia, Bangkok Airways, Eva Air, Haeco, Singapore Airlines, Lot, Olympic, CSA, Sabena Technics, Eurowings, Nordam Europe & Singapore Bedek, China Eastern, Transasia, China Northwest, Tarom Gameco, Schreiner, Joramco, Asseman, Emirates, Malaysian Airlines, Varig, Estonian, Spanair, Quatar, Cargolux...

9 Basic Products: Typical portable aeronautical composite repair equipment developed by GMI, as commercially available today ELISA portable U/S inspection equipment LESLIE toolings for surface preparation ANITA portable hot bonding console Combined heating and vacuum equipment

10 Heating Elements Heating Equipment Control Units Portable Hot Bonder & heating blankets for in-situ curing of composite repairs Large multi-channel systems for workshop repair / curing of complex parts

11 Multi-zone heating control Example of multizone configuration, used for other demanding repair heating applications and corresponding heating blanket manufactured according to the definition calculated for this structure

12 Equipment for surface treatment Example of stepping configuration Examples of scarfing configuration

13 Advanced composite repairs to metallic parts on ATR aircraft Repair of an ATR-72 aluminium floor beam using a bonded carbon patch, performed in situ by GMI Aero, in cooperation with the ATR company.

14 GMI Training Activities Level 1: Transition of Sheet Metal Technicians to Composite Repair Operators Level 2: Specialized training of composite repair operators to increase level of expertise

15 Main types of Composite Repairs Non-structural repairs: Well-established since many years in a variety of aircraft and structures. Structural Repairs: Target: Temporary Bolted Repair Restoring Strength /Stiffness Permanent Bolted Repair Permanent Bonded Repair : The ultimate challenge!

16 Basics of Adhesive Bonding Adhesive bonding is an interdisciplinary topic between surface physics, polymer chemistry, traditional engineer disciplines and aging. This all makes it interesting but it also takes time to understand what's essential. So, specific training is required in order to ensure adequate understanding of all involved factors related to this important and innovative technique.

17 Basics of Adhesive Bonding Welding vs. adhesive bonding: Welding is done by: Well trained specialists With certified materials Defined constructions and Supported by standardisation and regulations. And still there are a whole lot of failures of welded structures. Welding vs. adhesive bonding: Adhesive bonding is usually done: By untrained people With proprietary adhesives On undefined material surfaces. And yet it works. So adhesive bonding must be principally a reliable technique if minimum requirements are fulfilled. The adhesive is your friend, but you need to be adequately trained to appreciate and appropriately handle it!.

18 Typical Composite Repair Setups Laminated Structures Sandwich Structures

19 Basic steps involved in a bonded composite repair process 1. NDI Damage Assessment 2. Damage Removal - Surface Preparation 3.Vacuum Bagging 4.Heating for curing

20 Current situation in training. Currently very few of independent airframe MRO technicians have specialty training and internal certification to perform complex composite repairs (e.g. layup, vacuum bonding, etc.) Yet a large percentage of a typical MRO s technicians fit into the sheet metal or structures category Composite repair training is intensive and time consuming: 2-3 weeks for advanced repair class Expensive tooling and equipment required for instruction and practice For many MROs, this makes the tooling also unavailable for production use Trade and skill classifications is required As the number of employees become trained and complexity increases: Unions will likely be pushing for a separate, higher paid, classification In the non-union environment, demand and skill requirements will likely influence a higher wage for retention

21 The bonded composite repair training challenge.... Detailed in-depth repair training for new technicians and training in the latest methods for current composite repair shops are essential. New designs requiring different training, understanding and experience Differences in material coefficients of thermal expansion (CTE) Restoring the electrical conductivity mesh for lightening protection Repair material selection must be sensitive to potential galvanic corrosion Higher process sensitivity Using backup to avoid fiber breakout Using dull drill bits or incorrect speeds/feeds can burn composite Drilling through metal/composite stack-ups can damage composite holes We have to draw general rules from detailed skill list in order to pass from expert hand artists technician to process understanding technicians.

22 Experimental application of Repair on A350 Panel: Is it really that simple???

23 Failures because of inadequate calculation of thermal effects Structural adhesives can usually stand temperatures up to 150 C But: The real temperature of a part is a result of energy in and out. So heat conductivity is a critical parameter often not taken into account. Failures are then (as usual) used to blame the adhesive. Delamination of a bonded patch due to overheating as a result of neglected reduced heat conductance through the bondline

24 Training and Certification Standards for Composite Maintenance & Repair Main Challenges faced when repairing composite parts: a. Surface preparation (Stepping / Scarfing) Reproducibility of repairs b. Heat transfer during curing Temperature Homogeneity of repairs in order to ensure bonding strength / durability Such challenges grow bigger as complexity of parts increases!

25 Training and Certification Standards for Composite Maintenance & Repair Answer to Challenges: a.innovations b.training & Certification

26 Latest innovations related to bonded composite repair application Participation to EU Research Programs Brite Euram (FP5), FP6, FP7, H2020, Cleansky JTI, Research for the Benefit of SMEs, Eurostars & EUROGIA+ In cooperation with Co-funded by:

27 Latest Innovations of various TRLs Repairs using OLGA for patch preparation (to overcome porosity issues) and secondary bonding on aircraft.

28 Latest Innovations of various TRLs Adaptive blankets to achieve T homogeneity during repair co-curing on thick / geometrically complex structures (customized to A350 / B787 applications)

29 Latest Innovations of various TRLs ADVANCED Out-Of-Autoclave (OOA) Heating Solution for Production and Repair of Composites

30 Latest Innovations of various TRLs Heating Pins - Heating Bolts for repair inside drilled holes of 3-20mm diameter

31 Training and Certification Standards for Composite Maintenance & Repair Answer to Challenges: a.innovation b.training & Certification

32 Training on treatment of highly curved parts of big dimensions Key issue: Reproducibility of repairs

33 Training on how to use advanced surface preparation equipment: Key issue: Reproducibility of repairs

34 Training to Comprehend Repair Heat Transfer principles Key issue: Temperature homogeneity Thermal transfer routes in the repair area Heat Equilibrium = Algebraic Sum of Thermal Routes No : The temperature that you read at each time step at each point is the algebraic sum of these factors as they affect the exact point that you have installed your thermocouple (i.e. according to geometrical dimensions, materials, dimensions etc.): This is why we get significantly different temperatures at each point of the repair area. 34

35 Understanding the effect of heat sinks Key issue: Temperature homogeneity Additional structure close to the repair area, may create significant temperature differences, as it will act as a heat sink. In this example, a drop in temperature of more than 10 degrees can be viewed at the center of the repair area. Simulation of temperature distribution for a 20x20cm heating blanket to a flat plate. Simulation of temperature distribution for a 20x20cm heating blanket to the same plate, with a stringer at the center, as shown in the picture above. Temperature drop area. 35

36 Training on use of heating blankets for specialized demanding applications Key issue: Temperature homogeneity Example of heating blankets for Airbus A380 thrust reverser repair

37 Development of Training/Qualification Programs for Composite Maintenance Technicians Advisory Circular AC No (US DoT, 8/3/2011) Guideline for organizations to develop a formal training program for qualification of composite technicians

38 Development of Training/Qualification Programs for Composite Maintenance Technicians Advisory Circular AC No (US DoT, 8/3/2011) Sample Course Curriculum - Basic Knowledge of Composite Technology Objectives: 1. Understand the Basics of Composite Materials Technology 2. Understand the Basics of Composite Materials Maintenance and Repair 3. Understand Other Critical Elements of Composite Maintenance and Repair 4. Knowledge of Composite Maintenance Research and Industry Developments 5. Understand Roles and Responsibilities 6. Identify and Describe Information in Required Documentation 7. Describe Safe Handling of Advanced Composite Materials

39 Development of Training/Qualification Programs for Composite Maintenance Technicians Advisory Circular AC No (US DoT, 8/3/2011) Inspection, Damage Detection and Characterization - Composite Repair Procedures Objectives: 1. Recognize Composite Damage Types and Sources 2. Describe Composite Inspection Procedures 3. Describe Composite Laminate Fabrication and Bonded Repair Methods 4. Perform a Simple Bonded Composite Repair 5. Describe Composite Laminate Bolted Assembly and Repair Methods

40 Conclusions In any type of work is easier to obey the rules if you have a basic understanding of the underlying science and technology Example: The importance of good surface preparation when adhesively bonding metals and other materials. When taking up any new job, hobby or other activity it almost always means learning new words and their meaning in the context of the new occupation. In composites this means words like: CFRP, GFRP, prepreg, adhesive bonding, surface preparation, temperature homogeneity

41 Conclusions (continued ) Aeronautical industry faces increased challenges for repair of composites due to their continuously increased volume and complexity in modern aircraft. Repair practices that may have been acceptable in the past could be inadequate on the newer, heavily-stressed structures coming into use on new generation aircraft. The answer to those challenges can only come from innovations and appropriate training & certification of technical personnel. Detailed in-depth repair training for new technicians and training in the latest methods for current composite repair shops are essential.

42 Conclusions (continued ) Training should now target in upgrading operators knowledge from a mere technical ability to full process understanding, in order to extend the range of application of bonded repairs to Class I aircraft structures.

43 Contemporary Challenges in Continuing Airworthiness and Maintenance Education and Training Mapping the Way Forward Training and Certification Standards for Composite Maintenance & Repair Roland Chemama, GMI Aero President Thank you for your attention!