Common Core 107

Aviation Fundamentals

107.1 Describe the following terms pertaining to motion:

1.        Inertia- The resistance of an object to start moving or changing its motion.  This resistance to change is measurable since it takes more force to start an object in motion than keep it in motion.

2.        Acceleration- The rate of change of the velocity of matter with time. If our ship, which is presently moving at 10 knots, is moving at 18 knots one hour from now and 21 knots 2 hours from now, it is said to be accelerating at a rate of 3 knots per hour.

3.        Speed- The rate of movement or motion in a given amount of time. Speed is the term used when only the rate of movement is meant. If the rate of movement of a ship is 14 knots, we say its speed is 14 knots per hour.

4.        Velocity- Velocity is defined as speed with a direction such as a wind velocity of  18knots at 215 degrees.

107.2 Define the following laws of motion:

1.        Newton’s First Law: According to Newton's first law of motion (inertia), an object at rest will remain at rest, or an object in motion will continue in motion at the same speed and in the same direction, until acted upon by an outside force.

2.        Newton's Second Law: The second law of motion (force) states that if an object moving with uniform speed is acted upon by an external force, the change of motion, or acceleration, will be directly proportional to the amount of force and inversely proportional to the mass of the object being moved.

3.        Newton's Third Law: The third law of motion (action and reaction) states that for every action there is an equal and opposite reaction. This law is demonstrated with a balloon. If you inflate a balloon and release it without securing the neck, as the air is expelled the balloon will move in the opposite direction of the air rushing out of it.

107.3 Define Bernoulli's principle.

The principle states that when a fluid flowing through a tube reaches a constriction or narrowing of the tube, the speed of the fluid passing through the constriction is increased and its pressure decreased.

107.4 Discuss the following weather warnings and their effect on naval aviation:

a. Wind warning

Please note: one knot equals approximately 1.15 mile-per-hour. Destructive weather poses a significant threat to personnel, aircraft, ships, installations, and other resources. Adequate and timely weather warnings, coupled with prompt and effective action by commanders concerned, will minimize loss and damage from destructive weather.

1. Small craft

Harbor and inland waters warning for winds, 33 knots or less, of concern to small craft. The lower threshold for issuing such warnings is set by local authority.

2. Gale

Warning for harbor, inland waters, and ocean areas for winds of 34 to 47 knots.

3. Storm

Warning for harbor, inland waters, and ocean areas for winds of 48 knots or greater.

b. Tropical cyclone warnings

Tropical cyclones are systems of cylonically rotating winds characterized by a rapid decrease in pressure and increase in winds toward the center of the storm. Their size may vary from 60 nautical miles to over 1000 nautical miles. Three stages of intensity are associated with tropical cyclones:

1. Tropical depression

Warning for land, harbor, inland waters, and ocean areas for winds of 33 knots or less.

2. Tropical storm

Warning for land, harbor, inland waters, and ocean areas for winds of 34 to 63 knots.

3. Hurricane/typhoon

Warning for land, harbor, inland waters, and ocean areas for winds of 64 knots or greater.

Thunderstorms are small scale storms, invariably produced by a cumulonimbus cloud
and always accompanied by lightening and thunder.

A tornado is a violently rotating column of air, usually in the form of a funnel, extending from a thunderstorm cloud to the ground. A tornado is one of the most violent and destructive storms known. Its winds can reach from 100 to 250 knots, although their winds have never been measured directly.

1. Thunderstorm warning

Thunderstorms are within 3 miles of the airfield, or in the immediate area.

2. Severe thunderstorm warning

Thunderstorms with wind gusts to 50 knots or greater and/or hail of 3/4 inch in diameter or greater is forecast to impact the warning area.

Tornadoes have been sited or detected by RADAR in or adjacent to the warning area, or have a strong potential to develop in the warning area.

107.5 Describe the following aerodynamic terms:

1.        Lift- The force that acts, in an upward direction, to support the aircraft in the air. It counteracts the effects of weight. Lift must be greater than or equal to weight if flight is to be sustained.

2.        Weight- The force of gravity acting downward on the aircraft and everything on the aircraft.

3.        Drag- The force that tends to hold an aircraft back. Drag is caused by the disruption of the air about the wings, fuselage or body, and all protruding objects on the aircraft. Drag resists motion.

4.        Thrust- The force developed by the aircraft's engine, and it acts in the forward direction. Thrust must be greater than or equal to the effects of drag in order for flight to begin or be sustained.

5.        Longitudinal axis- An imaginary reference line running down the center of the aircraft between the nose and tail. The axis about which roll occurs.

6.        Lateral axis- An imaginary reference line running parallel to the wings and about which pitch occurs.

7.        Vertical axis- An imaginary reference line running from the top to the bottom of the aircraft. The movement associated with this axis is yaw.

107.6 State the three primary movements of aircraft about the axis.

1.      Pitch - The movement of the aircraft about its lateral axis. The up and down motion of the nose of the aircraft.

2.      Yaw - The movement of the aircraft about its vertical axis. The drift, or right or left movement of the nose of the aircraft.

3.      Roll - The movement of the aircraft about its longitudinal axis. The movement of the wing tips; one up and the other down.

107.7 Identify and state the purpose of the primary flight controls for:

1. Fixed wing aircraft- Elevator, Aileron, and Rudder

2. Rotary wing aircraft- Cyclic Pitch, Collective Pitch, and Rotary Rudder

107.8 State the purpose of the following flight control surfaces:

1.        Flap- Gives the aircraft extra lift. The purpose is to reduce the landing speed, thereby shortening the length of the landing rollout. They also facilitate landing in small or obstructed areas by permitting the gliding angle to be increased without greatly increasing the approach. The use of flaps during takeoff serves to reduce the length of the takeoff run.

2.        Spoiler- Used to decrease wing lift. However, the specific design, function, and use vary with different aircraft. In the retracted position, they are flush with the wing skin. In the raised position, they greatly reduce wing lift by destroying the smooth flow of air over the wing surfaces.

3.        Speed brakes- Hinged or moveable control surfaces used for reducing the speed of aircraft. On some aircraft, they are hinged to the sides or bottom of the fuselage; on others they are attached to the wings.

4.        Slats- Slats are movable control surfaces attached to the leading edge of the wing.  Like the flaps, slats increase the lift produced by the wing at a cost of increased drag.  No often called leading edge flaps.

5.        Horizontal stabilizer- Provides stability of the aircraft about its lateral axis. It serves as the base to which the elevators are attached. On many high speed aircraft the elevator and horizontal stabilizer are combined into one control surface called a stabilator.

6.        Vertical stabilizer- Maintains the stability of the aircraft about its vertical axis. This is known as directional stability. The vertical stabilizer usually serves as the base to which the rudder is attached.

7.        Tail rotor- Mounted vertically on the outer portion of the helicopter's tail section. The tail rotor counteracts the torque action of the main rotor by producing thrust in the opposite direction.  It is can act as a rudder for the helicopter or allow the helicopter to fly sideways.

107.9 Explain the term angle of attack.

The angle at which a body, such as an airfoil or fuselage, meets a flow of air.

107.10 Explain the term autorotation.

A method of allowing a helicopter to land safely from altitude without using engine power by making use of the reversed airflow up through the rotor system to reduce the rate of descent. Accomplished by lowering collective pitch lever to maintain rotor rpm while helicopter is decreasing in altitude, then increasing collective pitch at a predetermined altitude to convert inertial energy into lift to reduce the rate of descent and cushion the landing.

107.11 State the components of a basic hydraulic system.

1.      A reservoir to hold a supply of hydraulic fluid.

2.      A pump to provide a flow of fluid.

3.      Tubing to transmit the fluid.

4.      A selector valve to direct the flow of fluid.

5.      An actuating unit to convert the fluid pressure into useful work.

107.12 Describe and explain the purpose of the main components of landing gear.

1.      Shock Strut Assembly - Absorbs the shock that otherwise would be sustained by the airframe.

2.      Tires - Allows the aircraft to roll easily and provides traction during takeoff and landing.

3.      Wheel brake assembly - Used to slow and stop the aircraft. Also used to prevent the aircraft from rolling while parked.

4.      Retracting and extending mechanism - All the necessary hardware to electrically or hydraulically extend and retract the landing gear.

5.      Side struts and supports - Provides lateral strength/support for the landing gear.

107.13 State the safety precautions used when servicing aircraft tires on aircraft.

Modern aircraft wheels and tires are among the most highly stressed parts of the aircraft. High tire pressure, cyclic loads, corrosion and physical damage contribute to failure of aircraft wheels. Always approach the tires from fore and aft. When inflating, stand well clear.

107.14 State the 5 basic sections of a jet engine.

1.      The intake which is an opening in the front of the aircraft engine that allows outside or ambient air to enter the engine.

2.      The compressor which is made of a series of rotating blades and a row of stationary stator vanes. The compressor provides high-pressure air to the combustion chamber (or chambers).

3.      The combustion chamber where fuel enters and combines with the compressed air.

4.      The turbine section which drives the compressor and accessories by extracting some of the energy and pressure from the combustion gases.

5.      The exhaust cone which is attached to the rear of the engine assembly and eliminates turbulence in the emerging jet, thereby giving maximum velocity.

107.15 Describe the following engine systems:

1.        Turbojet- Projects a column of air to the rear at an extremely high velocity. The resulting effect is to propel the aircraft in the opposite or forward direction.

2.        Turboshaft- Delivers power through a shaft to drive something.  They have a high power to weight ratio and are used on helicopters.

3.        Turboprop- Propulsion is accomplished by the conversion of the majority of the gas-energy into mechanical power to drive a propeller. This is done by the addition of more turbine stages. Only a small amount of jet thrust is obtained on a turbo prop engine.

4.        Turbofan- Basically the same as a turbojet except that the compressor section is expanded so that part of it becomes a duct-enclosed axial-flow fan. The fan will produce 50 percent or more of the engine's total thrust.

107.16 State the purpose of an afterburner.

Used during takeoff and combat maneuvering to boost the normal thrust rating of a gas turbine engine through additional burning of the remaining unused air in the exhaust section.

107.17 State the NATO symbols for the following fuels and briefly explain the characteristics and reasons for the use of each:

1.        JP4-  F-40-Has a flame spread rate of 700-800 feet per minute and a low flash point of -10 degrees F or -23 degrees C. Never used on ships. Use of JP4 will normally cause an engine to operate with a lower exhaust gas temperature (EGT), slower acceleration, and lower engine RPM.

2.        JP5- F-44- Has a flame spread rate of 100 feet per minute, and a flash point of 140 degrees F or 60 degrees C. JP-5 is the only approved fuel for use aboard naval vessels. The lowest flash point considered safe for use aboard naval vessels is 140 degrees F. This is the Navy's primary jet fuel.

3.        JP8- F34-Has a flame spread rate of 100 feet per minute, and a flash point of 100 degrees F or 40 degrees C.

107.18 Describe the 3 hazards associated with jet fuel.

Eye, skin irritant, inhalation hazard.

107.19 Describe the symptoms of fuel vapor inhalation.

The symptoms include nausea, dizziness, and headaches. Fuel vapor inhalation can cause death.

107.20 Explain the purpose of the Auxiliary Power Unit (APU).

These power units furnish electrical power when engine-driven generators are not operating or when external power is not available. Most units use a gas turbine to drive the generator. The gas turbine provides compressed air for air conditioning and pneumatic engine starting. This makes the aircraft independent of the need for ground power units to carry out its mission.

107.21 Identify the reasons for and methods of Non-Destructive Inspection (NDI)

It is essential that defects be found and corrected before they reach catastrophic proportion. NDI can provide 100 percent sampling with no affect to the use of the part or system being inspected. Methods used may include visual, optical, liquid penetrate, magnetic particle, eddy current, ultrasonic, radiographic, etc. NDI is the practice of evaluating a part or sample of material without impairing its future usefulness.

107.22 Discuss icing and its effects on the performance of naval aircraft.

Ice on the airframe decreases lift and increases drag, weight, and stalling speed. The possibility always exists that engine system icing may result in loss of power. Icing can cause: loss of engine power, aerodynamic efficiency, loss of proper operation of control surfaces, brakes and landing gear, loss of outside vision, false instrument indications, and loss of radio.

107.23 State the purpose of the following:

1.        Pitot-static- The pitot-static system provided ram air (pitot) and static air for the barometric altimeter, airspeed indicator, RAWS, AOA, and True Airspeed computer. By providing the differing static pressure, altitude and air density correction can be computed.  The ram or pitot air gives airspeed information.

2.        Airspeed indicator- The airspeed indicator displays the speed of the aircraft in relation to the air in which it is flying. In some instances, the speed of the aircraft is shown in Mach numbers. The Mach number gives the speed compared to the speed of sound in the surrounding medium (local speed).

3.        Altimeters- The altimeter shows the height of the aircraft above sea level. The face of the instrument is calibrated so the counter or pointer displays the correct altitude of the aircraft.  There are two types of altimeters: barometric and radar.  The barometric altimeter shows approximate altitude above mean sea level.  The radar altimeter provides an altitude above ground.  Flying over mountains can give a barometric altitude of 14500 feet while a radar altitude of only 1500 feet.

4.        Rate-of-climb- The rate-of-climb indicator shows the rate at which an aircraft is climbing or descending.

5.        Attitude indicator- A pilot determines aircraft attitude by referring to the horizon. The instrument shows the pilot the relative position of the aircraft compared to the earth's horizon.  This gives the ability to fly when conditions prevent seeing the horizon such as in clouds or at night.

6.        Turn and bank indicator- Shows the correct execution of a turn and bank. It also shows the lateral attitude of the aircraft in straight flight. It consists of a turn indicator and a bank indicator.

7.        Navigation systems- Navigation systems and instruments direct, plot, and control the course or position of the aircraft.

8.        Identification Friend or Foe (IFF)- IFF is an electronic system that allows a friendly craft to identify itself automatically before approaching near enough to threaten the security of other naval units. All operational aircraft and ships of the armed forces carry transponders to give their identity when challenged.  Some modes are used by civil air traffic control while other modes are strictly military.

9.        Radio Detection And Ranging (RADAR)- A radio device used to detect objects at distances much greater than is visually possible. Detectable objects include aircraft, ships, land, clouds, and storms. Radar also shows their range and relative position.

10.     Magnetic (standby) compass- A direct-reading magnetic compass is mounted on the instrument panel. The face of the compass is read like the dial of a gauge.

11.     Communication systems- Radio equipment does not require interconnecting wires between the sending and receiving stations. It is the only practical means of communication with moving vehicles, such as ships or aircraft.

107.24 State the purpose of the following armament:

1.        Bombs- Any weapon other than a torpedo, mine, rocket or missile, dropped from an aircraft. Bombs are free-falling explosive weapons and may be unguided or "smart" or guided. Designed for release over enemy targets to reduce and neutralize the enemy's war potential by destructive explosion, fire, nuclear reaction, etc.

2.        Rockets- A weapon containing an explosive section and a propulsion section. A rocket is unable to change its direction of movement once fired. It can be launched from an aircraft without the need of heavy or complex gun platforms and without violent recoil. Since rockets are usually launched at close range, it's accuracy as a propelled projectile is higher than that of a free-falling bomb dropped, from high altitude.

3.        Missiles- A vehicle containing an explosive section, propulsion section, and guidance section. A missile is able to change direction or movement after being fired. Missiles are classified according to their range, speed, launch environment, mission and vehicle type.

4.        Mines- An underwater explosive put into position by surface ships, submarines, or aircraft. A mine explodes only when a target comes near or in contact with it. Their primary objective is to effectively defend or control vital straits, port approaches, convoy anchorages and seaward coastal barriers.

5.        Torpedoes- Self-propelled underwater missiles used against surface and underwater targets. Torpedoes are the primary weapons employed in antisubmarine warfare. They are designed to search, detect, attack and destroy submarines and surface ships.

107.25 Explain the purpose of the following:

1.        Circuit breaker- A protective device that opens a circuit when the current exceeds a predetermined value. Circuit breakers can be reset.

2.        Fuse- A protective device inserted in-line with a circuit. It contains a metal that will melt or break when current is increased beyond a specified value, thus disconnecting the circuit from its power source to prevent damage.   Fuses must be replaced.

107.26 Explain the following avionics terms:

Note: Ohm's Law states E=IR

1.        Voltage- The "driving force" behind current. Voltage, as applied to Ohm's Law, can be stated to be the base value in determining unknown circuit values. Designated by the letter (E).

2.        Current- The flow of electrons. Ohm's Law states that current is directly proportional to the applied voltage and inversely proportional to the circuit resistance. Designated by the letter (I).

3.        Resistance- The opposing force to the flow of electrons. As stated in Ohm's Law, current is inversely proportional to resistance. This means, as the resistance in a circuit increases, the current decreases proportionally. Designated by the letter (R).