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