Part 4- Commercial Aircraft Structure Metal Bond Repair

This SAE AIR 4938 – PART 4 curriculum is intended to meet the formal training requirement for individuals who intend to become certified as aircraft metal bond repair technicians.
Persons who successfully complete this aircraft structural repair training program are considered to be able to perform metal bonded repairs to metal structures in compliance with the manufacturers’ repair documentation or other acceptable repair data.
The teaching levels listed are considered the minimum required for a given task.
The hours for lecture and hands-on repair projects are the minimums required for each.
Many of the subjects require reinforcement through practical exercises.

Abbreviations used :

  • SAE: Society of Automotive Engineering
  • SAE– CACRC: Commercial Aircraft Repair Committee
  • SAE- AIR: Aerospace Recommended Practices document
  • SAE- ARP: Aerospace Recommended Practices
  • FAA:  Federal Aviation Administration
  • EASA: Europian Union Aviation Safety Authority 
  • MRO:  Aircraft Maintenance Repair & Overhaul 
  • EFC:   Earth & Flight Composites Training

Qualification to repair the structure to a serviceable condition will require additional experience in the form of on the job training under the supervision of a qualified individual
This course complies SAE-Int. PART 4 SAE-, CACRC AIR 4938C,  EASA, and FAA standards

SAE publications:

  • SAE- AIR 4844 – Composites and Metal Bonding Glossary
  • AIR 6291- Guidelines for Repair Process Evaluation of Aluminum Bonded Structure
  • FAA and EASA publications:
  • Title 14 Code of Federal Regulations, Part 147
  • EASA AMC 20-29 Composite Aircraft Structure
  • FAA AC 20-107B  Composite Aircraft Structure
  • FAA AC 43-214 Repairs and Alterations to Composite and Bonded Aircraft Structure

Day(-s): 5 / Tech code: TECH-104 PART 4


Advised prerequisites
Basic or equivalent knowledge in working with composites and preferably some knowledge of aluminum materials will be an advantage.
Preferably  attend our EFC- TECH-001 Basic course  or the new SEA-CACRC AIR 4839  Part 1 "General Structural Bonded  Composite Repair Course"
Please do contact us if in doubt to discuss with us  the current knowledge and contact us via  info@efcomposites.com
Student success will be in part based on the knowledge and skills possessed before course enrolment:
And including the following disciplines:

  • Basic technical mathematics
  • Reading comprehension
  • Fundamentals of engineering and technical drawings
  • General shop and hand tool usage
  • Use of precision measurement tools
  • Basic physics
  • Basic chemistry
  • Aircraft health and regulatory safety awareness
    (Need for PPE – Personal Protection Equipment) 

Personnel of technical departments or staff with some basic knowledge of composites who want to get familiar with Aircraft Structural Metal Bonded Repairs able to read and understand/repair metal bonded structure damage in accordance with the Aircraft type related OEM Repair Manuals.

Minimum required 4 and maximum 8 per course*.

* Courses will be confirmed as running by EFC as soon as sufficient applications are received!

SCOPE

This curriculum is intended to meet the formal training requirement for individuals who intend to become certified as aircraft metal bond repair technicians. Persons who successfully complete this aircraft structural repair training program are considered to be able to perform metal bonded repairs to metal structures in compliance with the manufacturers’ repair documentation or other acceptable repair data.

The teaching levels listed are considered the minimum required for a given task. The hours for lecture and hands-on repair projects are the minimums required for each. Many of the subjects require reinforcement through practical exercises.
Qualification to repair the structure to a serviceable condition will require additional experience in the form of on the job 

  • Must be able to work in groups of two with minimum supervision
  • Must be abel to keep a repair record in their personnal student logbook
  • Must be attentive to details
  • Will be able to repair adhesively bonded aluminum structure components by the OEM manual of the specific type of aircraft
  • Can work according to Safety regulations and can recognize hazardous materials & situations
  • Can assess the kind of damage by NDI, photography & Recordkeeping 
  • Can perform various types of damage according to the OEM manual:
    – half dept core repair with septum placement
    – full dept core repair with aerodynamically flush
  • Can surface prep. aluminum structure repair area before bonding following the OEM manual using Corrosion Inhibiting primer – Surface pre-treatment
    Boe-gel / Sol-Gel AC130-2
  • Can successfully fabricate aluminum ASTMD test (witness) coupons (witness samples) along with the repairs such as Lap shear, Climbing Drum peel, and Wedge test.
  • Will be able to handle and install foam and film adhesives and positioning (Scrim) cloth
  • Will be able to monitor total material, Lifecycle, 'Out time' of all frozen materials using a 'Freezer Out time form'.
  • Knows how to use and program and monitor different heat and hot bonding systems for curing
  • Can and can fabricate quick composite reinforced support tooling for an aluminum bonded structure
  • Must be able to read and understand Technical Englisch and read and understand the criteria required as written in SAE- Aerospace document AIR4844 (last revision)
  • Can perform a Post-Repair inspection, photography repair & Recordkeeping 

1- Introduction to Aircraft Metal bond Structure               Level1    ( 0,5 hour)
Objective: Given discussion, lecture, and feedback, the student will be able to describe the metal bond application and describe critical elements as evaluated by the instructor.

  • Common Metal bond Applications
  • Critical Issues in Aircraft Metalbond Maintenance, Repair, and Overhaul
  • AIR6291, Guidelines for Repair Process Evaluation of Aluminum Bonded Structure

2- Metalbond-Specific Repair Material Requirements        Level 1  (1 hour)
Objective: Given discussion, lecture, and feedback, the student will be able to describe and identify the correct aluminum alloy and core for a specific repair as evaluated by the instructor.

Aluminum Alloy Selection 

  • Bare versus Clad
  • Pre-Primed Sheet
  • Heat Treatments
  • Alu Core Material
  • Forms
  • Alloys
  • Surface Treatments
  • Discussion of Bonding Other Metals

3   Adhesion                                                                             Level 1   (1 hour)
 Objective: Given discussion, lecture, feedback, the student will be able to describe the factors of adhesion as evaluated by the instructor.

  • Chemical Bonding Compared to Mechanical Bonding
  • Surface Tension and Surface Energy
  • Types of Failure
  • Adhesion
  • Corrosion
  • Surface Prep and Contamination
  • Cohesion
  • Mixed Mode

4   Safety and Environment                                                    Level 1      (1 hour)
Objective: Given discussion, lecture, feedback, the student will be able to demonstrate proper Personal Protective Equipment (PPE) use and describe the data available to safely use and dispose of the hazardous material as evaluated by the instructor.

  • SDS (Safety Data Sheet)
  • Waste Disposal
  • Personal Protection Equipment (PPE)

5.    Surface Preparation and Time Limitations        Level 3     (2 hours)
Objective: Given discussion, lecture, practice, and feedback, the student will be able to describe and prepare the metal surface as required by the repair document, to include prior surface treatment removal, surface cleaning, chemical treatment, and correct primer application as evaluated by the instructor. Two of the surface preparation methods listed below are taught at Level 3.        

  • Solvent Cleaning
  • Anodizing
    Phosphoric Acid

    • Phosphoric Acid Non-Tank Anodizing (PANTA)
    • Tank Method
    • Phosphoric Acid Containment System (PACS)
    • Boric/Sulphuric Acid
    • Chromic Acid
  • Chemical Conversion-Hydrofluoric Acid/Alodine
    Sol-Gel 

    • Boe-Gel (Sol Gel AC 130-2)
    • Pasa Gel
    • Grit Blast Silane
    • FPL Etch (improved)
    • Alodine
       
  •  Mechanical AbrasionPrimers
  • Primer Thickness Requirements
  • Time Limits
  • Proper Handling and Storage of Prepared Surfaces
  • Acceptance Criteria
    Water Break Free Test
    Use of Polarizing Filter

6.   Adhesives  Level 1  (0,5 hour)
Objective: Given discussion, lecture, feedback, the student will be able to describe and identify the correct adhesive, its application, handling, and storage requirements as evaluated by the instructor.

  • Film & Foam Adhesives
  • Paste Adhesives
  • Core Splice Adhesive
  • Proper Handling and Storage

7. Metal bond-Specific Design Considerations (Level 1) 1 hour
    Objective: Given discussion, lecture, and feedback, the student will be able to describe metal bond part design requirements as evaluated by the instructor.

  • Impact Shields
  • Corrosion Resistance
    • Interfacial Hydration (Moisture Ingression)
  • Drainage Paths
  • Isolation Layers
  • Acoustical Treatments and Layers
  • Electromagnetic Concerns
  • Aerodynamic Considerations

8.  Heat Transfer and Cure Cycle Management  Level 3  (1 hour)

Objective: Given discussion, lecture, practice, and feedback, the student will be able to describe and control the cure cycle to meet the repair document requirements as evaluated by the instructor. At least two types of equipment listed below are trained at  Level 3.

  • Heat Transfer Basics
  • Equipment Limitations
  • Autoclave
  • Oven
  • Hot Bonders
  • Heat Blankets
  • Hot Air Blowers
  • Heat Lamp
  • Infrared Heaters
  • Thermocouple Placement
  • Insulation and Airflow Control

9. Pressure Requirements  Level 3 (1 hour)

Objective: Given discussion, lecture, practice, and feedback, the student will be able to describe pressure requirements, place the correct core vent materials, and control the pressure to meet the repair document requirements as evaluated by the instructor.

  • Vacuum Levels
  • Positive Pressure
  • Core Venting
  • Air Entrapment

10. Source Documents  Level 2  (1 hour)
Objective: Given discussion, lecture, practice, and feedback, the student will be able to identify, describe, and comply with repair documents as evaluated by the instructor.

ATA Spec 2200/S1000 
Structural Repair Manuals:

  • Allowable Damage Limits (ADL)
  • Repair Limits

Component Maintenance Manual
Engineering Orders
Maintenance Organization Specific Documents
SAE AMS-CACRC ARPs
Regulatory Documents:

  • Airworthiness Directives
  •  Service Bulletins
  •  Advisory Circulars
  • Rule Making Task

Material and Processes Specifications

  •  OEM
  •  Vendor
  •  Internal

11. Repair Considerations   Level 3   (3 hours0

Objective: Given discussion, lecture, practice, and feedback, the student will be able to identify damage; evaluate repair considerations; and select, form, and fit check the repair parts to the requirements of the repair document as assessed by the instructor.

Damage Assessment and Limitation Corrosion

  • Contamination
  • Dents
  • Dis-bonds
  • Scratches, Nick's, and Gouges
  • Punctures
  • Crack
  •  Lightning Strike/Heat Damage
  • Proximity to Other Damage and Repairs
  • Material Selection and Substitution
  • Repair Part Sizing
  • Very film Check
  • Core Selection and Sizing
  • Septum
  • Bondline Thickness Control
  • Tooling Requirements
  • Contour Management/Material Forming
  • Damage Removal/Previous Repair Removal
  • Contaminant Removal/Prevention
  • Thermal Management
  • Effect of Vacuum Levels on Film Adhesives
  • Vacuum Bagging Techniques
  • Contact Materials

12. Inspection Techniques  Level 1   (1 hour)

Objective: Given discussion, lecture, practice, and feedback, the student will be able to describe inspection methods and conduct at least tap test, visual, and polarised light inspections to Level 3 as evaluated by the instructor.

  • Film Thickness Measurement
  • Bond Testers
     Harmonics Resonance
     Ultrasonic
  •  Tap Test
  •  Visual (Corrosion, Contaminants, Exposed Metal, Water Break Free Test)
  •  Polarized Filter Inspection
  •  X-Ray
  • Thermography
  • Eddy Current
  • Conductivity
  • Hardness

 

 

13. Hands-On Exercises Level 3 ( 25.5 hours)

Objective:
Given discussion, lecture, practice, and feedback, the student will be able to demonstrate proper safety practices while exhibiting the skills necessary to repair metal bond structures utilizing pre-bond treatments, film, and paste adhesives, metal parts, vacuum bagging techniques, and hot bond equipment. By the end of the training program, the students must demonstrate these skills by accomplishing a minimum of three of the repairs listed below to the instructor and meet the criteria in the repair documentation. The student must also destructively test one of the repairs listed below and identify failure mode in addition to the wedge test, lap shear test, Floating roller peel test and Peel test. 
A. Repairs
Dent Repair
Skin and Core Repair or One Side Flush Repair/Hald depth core repair with Alu. septum
v. Skin Crack Repair
All students have to fill in a personal logbook wherein al steps and OEM chapters used are noted performing  the actual repairs
B. Prepare samples for Destructive Testing according to the ASTM standard testing methods
Identify Failure Modes
Wedge Test
Lap Shear test
Floating Drum peel test
Peel test
 
Assessment Criteria by the Instructor using a checklist per student:
a. Damage removed without causing additional damage
b. Surface preparation meets OEM repair document requirements
c. Correct repair materials identified
d. Repair patch/doublers are positioned correctly and must have the correct sheet thickness
e. Cure cycle(s) meets repair document requirements
f. Repair meets post-repair inspection requirements

14. Written Exam (1 hour)

  • The examination will be Multiple choice questions from each of the teachings Level 1-3    (The test will be a closed book)
  • The minimum passing grade for all written exams shall be 75% and all grades shall be recorded in the individual’s training records.
  • The examination can be conducted by a Part 147 organization approved Examiner upon request If your company has its own Part147 the can approve their own exam along with the certificate.
  • The practical mark will be the average of all marks gained from the practical exercises
  • A certificate of accomplishment is handed out to each participant
  • Assessment activities are built into our courses, to give feedback on the achievement and personal potential and kept a record in their personal logbook.
  • The outcome of the participant's Examination, and assessment document and a filled-in logbook of their practical per student will be digitally sent to your company responsible manager or HR department.
  • We also comply with the European  GDPR rules as effective on May 25th, 2018 concerning storage of private information of participants who attended our courses
15. Practical Assessment test
The practical assessment will be a separate, hands-on repair. The practical assessment shall be similar to one of the hands-on exercises. 
 
Assessment:
a. Damage Assessment
b. Damage Removal
c. Repair Preparation
d. Repair Lay-up
e. Vacuum Bagging
f. Repair Cure
g. Post Repair Inspection
h. Record Keeping
  • Practical Assessment; a checklist is used to evaluate the practical. Student’s performance will be daily monitored throughout the program.
  • Assessment activities by the instructor are built into our courses, to give positive feedback on the achievement and personal potential and kept on record in an individual student logbook.
  • All grades will be recorded in the participant individual training records and kept on file for unlimited time*.
    *Compliant with Reference EASA Commission Regulation (EU) No 1321/2014
  • A certificate of accomplishment is handed out to each participant.along with a course content printout.
  • A final Outcome document is sent to the student and the company showing the examination and practical outcome per student

This course can also be held at our facility in Leipzig Germany at the facilities of our partner HEICO. If you have a need for this, please contact our purchasing manager Rolf Hovener via his page.

For your company to benefit, this course can be held ‘On-Site’ at your facility under certain conditions.
Click on this link to the Onsite information webpage!

Courses as noted on our course schedule page can be run on request to meet your required start and end date.

All listed course prices are Excl VAT. (Dutch VAT is 21%). EFC complies with Dutch tax laws. On request, companies can be sent an invoice instead of paying direct On-line with PayPal, IDEAL or credit card.

Payment is securely arranged via Mollie.nl . More information can be found on the website of Mollie.

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