Airframe Mechanic Certification Aircraft Structures & Materials 3 — Questions and Answers
Question 1: What is the primary advantage of using titanium alloys in aircraft construction?
- Lower cost than aluminum
- High strength retention at elevated temperatures (Correct answer)
- Easier to machine than steel
- Higher electrical conductivity
Correct answer: High strength retention at elevated temperatures
Titanium alloys maintain their strength at elevated temperatures, making them ideal for engine nacelles, firewalls, and high-heat areas.
Question 2: In a semi-monocoque structure, which components share the load with the skin?
- Fuel tanks and hydraulic lines
- Frames, bulkheads, stringers, and longerons (Correct answer)
- Landing gear struts and engine mounts
- Control cables and pulleys
Correct answer: Frames, bulkheads, stringers, and longerons
Semi-monocoque structures use internal framework consisting of frames, bulkheads, stringers, and longerons working together with the skin to carry loads.
Question 3: What is 'corrosion' in the context of aircraft metals?
- Fatigue cracking from repeated stress cycles
- Electrochemical deterioration of metal by reaction with the environment (Correct answer)
- Deformation of metal under sustained load
- Microscopic cracking caused by hydrogen embrittlement only
Correct answer: Electrochemical deterioration of metal by reaction with the environment
Corrosion is the electrochemical deterioration of metal through chemical reaction with moisture, oxygen, or other environmental agents.
Question 4: Which type of corrosion occurs at the junction of two dissimilar metals in the presence of an electrolyte?
- Intergranular corrosion
- Galvanic corrosion (Correct answer)
- Stress corrosion
- Fretting corrosion
Correct answer: Galvanic corrosion
Galvanic corrosion occurs when two dissimilar metals are in electrical contact in the presence of an electrolyte, causing the more anodic metal to corrode.
Question 5: What does 'anodizing' do to an aluminum surface?
- Applies a zinc chromate primer coat
- Increases the thickness of the natural oxide layer for corrosion protection (Correct answer)
- Plates the surface with cadmium
- Removes all surface oxides for better bonding
Correct answer: Increases the thickness of the natural oxide layer for corrosion protection
Anodizing uses an electrochemical process to thicken the natural aluminum oxide layer, significantly improving corrosion and wear resistance.
Question 6: What is the primary structural function of wing ribs?
- To carry the spanwise bending loads
- To maintain the airfoil shape and transfer loads to the spars (Correct answer)
- To provide the main attachment for engines
- To connect the wing to the fuselage frame
Correct answer: To maintain the airfoil shape and transfer loads to the spars
Wing ribs maintain the airfoil cross-sectional shape and transfer aerodynamic loads from the skin to the spars.
Question 7: What is the recommended action when a mechanic discovers a crack in an aircraft structural component?
- Stop-drill the crack ends and return the aircraft to service
- Weld the crack closed and re-inspect after 100 hours
- Ground the aircraft and consult the manufacturer's structural repair manual (Correct answer)
- Apply epoxy filler and repaint the area
Correct answer: Ground the aircraft and consult the manufacturer's structural repair manual
Structural cracks require the aircraft to be grounded and repairs must follow the manufacturer's structural repair manual or an FAA-approved repair scheme.
Airframe Mechanic Certification Aircraft Structures & Materials 3
What is the primary advantage of using titanium alloys in aircraft construction?