AMT-211-New-PPT
AMT 211 Aircraft Materials Construction Repair II
Prepared by: Gian Carlo B. Gania
Instructor CAAP Lic # 161603
AMT A&P FDSA Aviation College of Science and Technology Inc.
Page 2: Preliminary Period Objectives
Understand sheet metal construction design philosophies
Recognize different types of metal
Familiarize with the tools for sheet metal fabrication and repair
Page 3: Introduction to Aircraft Materials
Early aircraft (e.g., Wright Flyer) used wood and fabric.
Progression to welded steel tubing to enhance strength and durability.
Transition to aluminum and stainless steel for both substructures and outer coverings.
Modern aircraft heavily utilize metallic components, although composite materials are emerging, particularly in control surfaces and non-structural components.
Future enhancements in composite materials likely to increase their structural role.
Page 4: Stresses and Structures
Aircraft structures must be strong, lightweight, streamlined, and durable.
Truss-type structures can be strong and lightweight but require superstructures to achieve a streamlined shape.
Monocoque designs offer strength with streamlined form but have limitations in material lifespan and cost.
Riveted or bonded sheet metal designs have become prevalent due to high production demands.
Page 5: Common Metals in Aircraft Structures
Aluminum alloys: about 90% of metals in civil aircraft; heat-treated for lightness and structural load capacity.
Other metals (10%): titanium, stainless steel, and exotic metals primarily for military or large transport aircraft.
Page 6: Types of Sheet Metal Structures
Monocoque: External skin supports most load; minimal internal framework.
Semimonocoque: Combines external skin with internal framework for load support.
Page 7: Structural Loads
Important for designers to account for all potential loads during component design.
Maintenance technicians must restore original strength and stiffness in repairs, often with engineering guidance.
Use of Structural Repair Manual or Maintenance Manual for preapproved repair designs.
Page 8: Types of Stresses in Aircraft Structures
Stress: Measure of internal forces due to external loads, expressed as force per unit area.
Key stress types: Tension, Compression, Bending, Torsion, Shear.
Tension and Compression are primary; others are variations based on these forces.
Page 9: Primary Stresses
Tension: Stress that pulls parts apart (e.g., weight on cable).
Compression: Stress that compresses or squeezes parts together (e.g., weight on a post).
Page 10: Bending Stress
Occurs when one side of a body is pulled apart while the other is compressed (e.g., diving board, wing spars).
Under flight conditions, wing spars experience complex bending stresses.
Page 11: Torsion and Shear Stress
Torsion: Twisting force causing tensile and compressive stresses across the member.
Shear: Resulting from opposing forces impacting the material from different sides (e.g., rivets under load).
Page 12: Rivet Joint Considerations
Need for strong yet lightweight repairs, balancing safety with weight considerations.
Design must ensure that fasteners fail before the structure under extreme loads.
Page 13: Bearing Strength
Defined as a sheet's ability to withstand being torn away from rivets in a joint, influenced by thickness and rivet size.
Page 14: Shear vs. Bearing Strength
Riveted structures must account for both shear strength of rivets and bearing strength of sheets.
Page 15: Transfer of Stresses within a Structure
Repairs must be designed to accept and transfer loads correctly to restore structural integrity.
Page 17: Materials for Sheet Metal Aircraft Construction
Aluminum Alloys: Pure aluminum is weak; strength improves significantly when alloyed (e.g., with copper, zinc).
Alloys can match or exceed steel's strength at a fraction of the weight.
Page 18: Alloying Agents
Common alloying agents include copper, magnesium, manganese, and zinc.
Aluminum alloy classifications by major alloying ingredient:
Ixxx (pure aluminum),
2xxx (copper),
3xxx (manganese),
4xxx (silicon),
5xxx (magnesium),
6xxx (magnesium and silicon),
7xxx (zinc),
8xxx (other elements).
Page 19: Alloy Breakdown Example
Breakdown includes purity, applications, and strength of various aluminum alloys commonly used in aircraft.
E.g., 2024 typically used for major structure.
Page 22: Clad Aluminum Alloy
Cladding of alloys with pure aluminum enhances corrosion resistance without compromising strength.
Page 23: Heat Treatment
Affects strength and utility; types include solution heat treatment and precipitation heat treatment for aluminum alloys.
Page 25: Magnesium Alloys
Highly lightweight, with working characteristics suited for aircraft.
Sourced from sea water or brine; insufficiently strong in pure form for structure.
Page 27: Titanium and its Alloys
Titanium is lightweight yet high-strength; used in various aircraft applications.
Classified types: Alpha, Alpha-beta, Beta Alloys based on chemical bonding.
Page 30: Stainless Steel
Corrosion-resistant, high-temperature applications in aircraft such as exhaust systems.
Categories: Austenitic, Ferritic, and Martensitic, based on their structure and properties.
Page 33: Aluminum Alloy-faced Honeycomb
Provides strength while remaining lightweight; used in fuselage panels and wings.
Page 34: Corrosion Prevention
Key for aluminum; methods include cladding and organic coatings.
Page 37: Fabrication Objectives
Knowledge about riveting procedures, fasteners, inspections, and repairs for sheet metal structures.
Page 38: Fabrication Techniques
Selecting appropriate materials and following standards, found in manufacturer publications or advisory circulars.
Page 40: Installation of Solid Rivets
Proper rivet installation is crucial for maximized structural integrity.
Page 41: Rivet Selection
Critical for maintaining strength integrity; bearing strength should ideally exceed shear strength.
Page 46: Rivet Layout Patterns
Careful rivet placement maximizes joint strength; must adhere to minimum installation specifications.
Page 50: Edge Distance
Minimum distance from rivet center to edge of joined materials; critical for joint integrity.
Page 53: Structural Fasteners
Fastener selection is crucial; some modern joints utilize adhesives instead.
Page 54: Solid Shank Rivets
Commonly used in aircraft; dimensions adjust during installation to ensure fit.
Page 55: Rivet Codes
Rivet part codes communicate size, head style, and alloy material.
Page 63: 2117 Aluminum Alloy (AD)
Commonly used for aircraft rivets; high strength and shock resistance.
Page 72: Introduction to Composite Materials
Gaining use in aerospace for their light weight and corrosion resistance.
Page 73: Laminated Structures
Composed of mixed materials to create specific structural properties; unchanged properties when combined.
Page 75: Applications of Composites
Used in various parts of aircraft including fairings, control surfaces, and structural elements.
Page 79: Fiber Orientation
Critical for strength; correct ply orientation ensures structural efficiency.
Page 88: Types of Fiber - Fiberglass
Utilized in secondary structures; advantages include cost and corrosion resistance.
Page 90: Kevlar®
Light and strong aramid fibers used for impact resistance in aircraft.
Page 94: Boron Fiber
Used for repairs; matches thermal expansion of aluminum, minimizing galvanic corrosion risk.
Page 97: Lightning Protection in Composites
Conductive layers apply to composite components as they are less conductive than aluminum.