AMT Aircraft Structures and Materials 2 — Questions and Answers
Question 1: What type of stress acts along the longitudinal axis of a structural member, tending to pull it apart?
- Shear stress
- Compressive stress
- Tensile stress (Correct answer)
- Torsional stress
Correct answer: Tensile stress
Tensile stress acts along the longitudinal axis and tends to elongate or pull a structural member apart.
Question 2: Which heat treatment process is used to relieve internal stresses in aluminum alloys after machining without significantly reducing hardness?
- Solution heat treatment
- Precipitation hardening
- Stress relieving anneal (Correct answer)
- Normalizing
Correct answer: Stress relieving anneal
Stress relieving anneal uses low temperatures to reduce residual stresses without substantially changing hardness.
Question 3: What is the purpose of a doubler plate installed on an aircraft skin?
- To reduce aerodynamic drag
- To reinforce a weakened or repaired area (Correct answer)
- To provide a corrosion barrier
- To reduce skin weight
Correct answer: To reinforce a weakened or repaired area
A doubler plate is bonded or riveted over a repaired or weakened skin area to restore structural strength.
Question 4: In a semi-monocoque fuselage, which members carry the primary bending loads?
- Formers and bulkheads
- Stringers and longerons (Correct answer)
- Skin panels only
- Gussets and brackets
Correct answer: Stringers and longerons
Stringers and longerons run longitudinally and carry the primary bending and tension/compression loads in a semi-monocoque structure.
Question 5: Which material property describes resistance to scratching and surface wear?
- Ductility
- Toughness
- Hardness (Correct answer)
- Elasticity
Correct answer: Hardness
Hardness is the material property that indicates resistance to surface indentation, scratching, and wear.
Question 6: What does the designation '2024-T4' indicate about an aluminum alloy?
- It contains 20% copper and was normalized at 24°C
- It is a 2000-series alloy in the solution heat-treated and naturally aged temper (Correct answer)
- It has a tensile strength of 24,000 PSI at 20% elongation
- It was manufactured using process 4 at facility 2024
Correct answer: It is a 2000-series alloy in the solution heat-treated and naturally aged temper
2024 identifies it as a copper-based aluminum alloy; T4 means it was solution heat-treated and naturally aged.
Question 7: Which type of composite fiber offers the highest stiffness-to-weight ratio commonly used in aircraft primary structures?
- Fiberglass (E-glass)
- Kevlar (aramid)
- Carbon/graphite fiber (Correct answer)
- Boron fiber
Correct answer: Carbon/graphite fiber
Carbon/graphite fiber provides the highest stiffness-to-weight ratio of commonly used composite fibers in primary aircraft structures.
AMT Aircraft Structures and Materials 2
What type of stress acts along the longitudinal axis of a structural member, tending to pull it apart?