4-14. Instead of pure aluminum, an aircraft builder uses aluminum alloys to get what desired result? 1. Stronger end product 2. More conductive metal 3. Less conductive metal 4. Softer end product 4-15. What is the main disadvantage of the use of magnesium in aircraft construction? 1. Weight 2. Strength 3. Hardness 4. Low resistance to corrosion 4-16. Which of the following alloys or metals is particularly valuable for use in or near salt water? 1. Magnesium 2. Titanium 3. Carbon steel 4. Pure aluminum 4-17. Transparent plastic becomes soft and pliable at approximately what minimum temperature? 1. 200°F 2. 225°F 3. 250°F 4. 275°F 4-18. What is the main advantage of reinforced plastic? 1. It has high strength-to-weight ratio 2. Its resistance to mildew and rot 3. Its ease of fabrication 4. All of the above 4-19. When several layers of bonding materials are used together and then mechanically fastened to conventional substructures, it is known as what type of construction? 1. Fiber glass 2. Composite 3. Metallic 4. Honeycomb core 4-20. The terms right or left used in relation to any of the structural units refer to the right or left hand of the pilot seated in the cockpit. 1. True 2. False 4-21. What is the main structure of an aircraft? 1. Engine 2. Wings 3. Fuselage 4. Tail 4-22. In the monocoque design, the main stress on an airplane is carried by what structural unit(s)? 1. Skin 2. Formers 3. Frame assemblies 4. Bulkheads 4-23. What is the main purpose of stringers in the semimonocoque design? 1. To add length to the frame 2. To carry concentrated loads 3. For attachment of the wings 4. For shape and attachment of the skin 4-24. What type of skin construction can withstand considerable damage and still hold together? 1. Semimonocoque 2. Monocoque 3. Plastic-impregnated 4. Wood-impregnated 4-25. Where is fuselage station 0 (zero) of an aircraft usually located? 1. Center of fuselage 2. Tail of aircraft 3. Nose of aircraft 4. Pilot's location 4-26. What is the unit of measurement in the station's numbering system? 1. Centimeters 2. Feet 3. Meters 4. Inches 4-27. Wings on an aircraft are designed for which of the following purposes? 1. Lift 2. Steering 3. Cutting through the air 4. Balancing the aircraft 4-28. What are the main structural members of the wing? 1. Beams 2. Ribs 3. Spars 4. Wires 4-24