A3-10. The main difference between a helicopter and an airplane is the way lift is
A3-11. A helicopter can hover.
A4-3. Shear is a stress exerted when two pieces of fastened material tend to separate.
A4-4. Bending is a combination of tension and compression.
A4-5. Torsion is the result of a twisting force.
A4-6. Metallic or nonmetallic materials.
A4-7. Aluminum, magnesium, titanium, steel, and their alloys.
A4-8. Transparent plastics, reinforced plastics, and composite materials.
A4-9. Monocoque, semimonocoque, and reinforced shell.
A4-10. Points on the fuselage are located by station numbers, at measured distances.
A4-11. The spars are the main structural members of the wing.
A4-12. "Wet wing" describes the wing that is constructed so it can be used as a fuel cell.
A4-13. Vertical stabilizer and horizontal stabilizer.
A4-14. Primary, secondary, and auxiliary.
A4-15. The purpose of speed brakes is to keep the airspeed from building too high when the
aircraft dives and to slow the aircraft's speed before it lands.
A4-16. The tricycle type of landing gear.
A4-17. The main advantage of rotary-wing aircraft is that lift and control are independent
of forward speed; rotary-wing aircraft can fly forward, backward, sideways, or
hover above the ground.
A4-18. Conventional fixed (skid type), retractable, and nonretractable.
A4-19. The tail rotor group.
A4-20. The possibility of leakage and contamination by foreign matter.
A4-21. The selector valve directs the flow of fluid.
A4-22. The actuating unit converts the fluid pressure into useful work.
A4-23. Hydraulic contamination is defined as foreign material in the hydraulic system of
A4-24. The two types of pneumatic systems are the storage bottle type and the type that has
its own air compressor.
A5-1. By its specification number or trade name.
A5-2. The head, grip, and threads.
A5-3. Machine screw, structural screw, and self-tapping screw.
A5-4. Nonself-locking nuts.