Aircraft Materials, Processes, and Hardware
Aircraft Materials and Processes
Steel Properties and Heat Treatment
(1.2) Elasticity – Deformation disappears.
(1.2) Hardness – Resists abrasion, penetration, and cutting.
(1.3) Loaded parts – Often made of steel.
(1.3) Ferrous materials – Iron as the main component.
(1.5) Best properties with high carbon content – Forging.
(1.5) Firewalls – Often made of stainless steel.
(1.6) Inconel – Used in high-temperature environments.
(1.16) Tempering – Performed after hardening.
(1.16) Why steel is tempered – To reduce brittleness.
(1.17) Carburizing – Carbon is added to the surface.
(1.17) Annealing – Softens material (temperature-dependent).
(1.17) Nitriding – Nitrogen reacts with iron.
(1.17) Normalizing – Material releases internal stress.
(2.2) Strength – Ability to resist deformation
Material Testing
(1.19) Rockwell tester – Indicates the depth of penetration.
(1.20) In Rockwell testing (Hardness) – C70 (hard) to C20.
(1.21) Impact test – Measures toughness.
(1.21) Hardness machines – Rockwell and Brinell.
(1.22) Tensile testing – Expressed in pounds per square inch (PSI).
(1.22) During Rockwell testing – The depth of the indenter’s penetration is measured.
Non-Ferrous Materials
(2.3) Non-ferrous – All metals except iron and its alloys.
(2.6) Combination (chemical) – Aluminum and copper alloys.
(2.6) 2024-T4 – Heat-treated aluminum alloy with pure elements.
(2.9) Copper – High electrical conductivity.
(2.9) Good for welding (alloy) – 5% aluminum, 2.5% tin.
(2.10) Inconel – Approximately 80% nickel.
(2.11) Alclad – Pure aluminum coating.
Heat Treatment and Material Properties
(2.14) Fastest quenching medium? – Brine.
(2.16) Hazardous material – Magnesium.
(2.16) If aluminum is too hard – Anneal it.
(2.16) Stress relieving – Used for titanium alloys.
(2.19) Measuring depth – Used in hardness testing.
(2.19) Annealing – Performed in still air conditions.
(2.19) Brinell testing – Requires a microscope for measurement.
(2.20) Pure aluminum – High corrosion resistance.
Composite Materials
(3.9) Warp – Direction along the length of the fabric.
(3.9) Warp (Resin)- The bonding material.
(3.8) Advantages of composite materials – Fibrous structure.
(3.12) Fabric type for pre-preg – Dry layout.
(3.26) Thermography – Detects thin areas and surface defects.
(3.34) Wet layups – A dry fabric is impregnated with resin.
Adhesive Bonding
(3.80) Open assembly – Adhesive is applied.
(3.80) Closed assembly – Period for structure bonding.
(3.80) Pot life – The usable life of an adhesive.
Fabric Covering
(3.102) Rib bracing – Applied before the fabric.
(3.102) Reinforcing tape – Used on rib caps.
(3.109) Maule puncher – Used to test fabric strength.
Corrosion
(4.7) Intergranular corrosion – Caused by improper heat treatment.
(4.7) Corrosion at the grain boundaries – Intergranular corrosion.
Aircraft Hardware
(5.4) Basic difference (bolts vs. screws) – On bolts, the nut is turned.
(5.4) Generally speaking, bolt strength is – Equal to the material’s strength.
(5.4) Aircraft bolts – Usually Class 3 fit.
(5.5) Aircraft bolts with a cross – Standard steel.
(5.16) Dowel pins – Used for shear loads.
(5.17) Shakeproof washers – Use only once.
(5.27) Shop head (rivets) – Formed with a hammer or pneumatic tool.
(5.34) Taper-Lok – Designed for high-stress loads.
Fittings and Lines
(6.3) Are fittings to be installed longer or shorter? – Longer.
(6.3) Main AN fitting components – AN sleeve and AN fitting.
(6.3) AN fitting colors – Steel (black), Aluminum (blue).
(6.6) How to change direction – Pipe is assembled.
(6.10) Fluid lines identification – On both sides.
(6.10) Flexible hoses – Can not be shortened.
Springs
(7.4) Nickel alloy springs – Used in higher temperatures.
Bearings
(8.2) Most common bearing materials – Shafts made of steel.
(8.2) Types of rolling bearings – Ball and roller.
(8.2) Bearing loads – Radial and axial.
(8.2) Deep-grooved bearings – Handle radial and thrust loads.
Gears
(9.3) Propeller reduction gears – Planetary and sun gears.
(9.5) Gear pair – Requires lubrication.
(9.5) Planetary gear – One sun gear.
(9.6) Step-up gear – Rotation increases, power decreases.
(9.6) Gears shall mesh – In the middle position.
(9.6) Idler gear – Keeps the direction of rotation the same.
Chains and Belts
(9.9) Pitch of a chain – Distance between two neighboring links.
(9.9) Belt drives – Tension is the most important factor.
Cables
(10.5) Turnbuckle – For minor adjustments to length and tension.
(10.7) Bowden cable – Flexible cable for mechanical remote energy transmission.
Electrical Wiring
(11.3) To prevent copper oxidation – Tin plating.
(11.4) Shielded cables – Grounded on at least one side.
(11.5) Desirable wire gauge – Smaller than 20 AWG.
(11.13) Identification markings – Every 15 inches.
(11.17) Splicing – Avoid in areas of extreme vibration.
(11.23) Choosing conduit size – 25% larger than the wire bundle.
(11.31) When crimping is too deep – The wire may break.
(11.32) Relay location- Junction boxes.
(11.34) On bulkhead – Use Class T connectors.
(11.34) Coaxial cables – Can be routed with other wiring.
(11.35) Connectors must withstand – Vibrations.
(11.36) Redundant systems – Use different connector types.
(11.37) Coaxial cables – Easily damaged.
(11.32) Relay – junction boxes
(11.34) on bulkhead – Class T
(11.34) coaxial cables – can be done with
(11.35) connectors must b- vibrations
(11.36) redundant – different connector
(11.37) coaxial cables – easyly damaged