Private Pilot FAA Written Exam Comprehensive Study Guide
Aerodynamic Principles and the Four Forces of Flight
The Four Forces of Flight: There are four fundamental forces acting on an airplane during flight:
Lift: The upward force created by the wings.
Weight: The downward force caused by gravity.
Thrust: The forward force produced by the engine/propeller.
Drag: The rearward, retarding force caused by air resistance.
Equilibrium of Forces: The four forces are in a state of equilibrium during unaccelerated flight.
Straight-and-Level Flight Relationships: When an aircraft is maintained in constant straight-and-level flight, the following relationships exist between the forces:
Bernoulli’s Principle: This principle explains the generation of lift by stating that air traveling faster over the curved upper surface of an airfoil creates a region of lower pressure on the top surface compared to the bottom.
Angle of Attack (AOA):
Definition: The angle formed between the wing chord line and the direction of the relative wind.
Stalling Angle: The specific angle of attack at which an airplane wing stalls remains the same regardless of the aircraft's gross weight.
Airfoil Surfaces:
Chord Line: The reference line from the leading edge to the trailing edge of an airfoil used to define the angle of attack.
Wing Flaps: These are surfaces used to increase the angle of descent during approach and landing without increasing the airspeed. They enable the pilot to make steeper approaches to a landing.
Primary and Secondary Flight Control Systems
Primary Flight Controls: These are the essential surfaces required to control the aircraft about its three axes. They include:
Ailerons: Control roll.
Rudder: Its specific purpose is to control yaw (movement about the vertical axis).
Elevator: Controls pitch, which is movement around the lateral axis.
Note on Primary Controls: Flaps are not considered a primary flight control surface.
Control Effectiveness: The effectiveness of every control surface increases as airspeed increases because there is a greater volume of airflow passing over them.
Secondary Flight Controls:
Spoilers: Identified as a secondary flight control device.
Trim Systems: These are designed to relieve the pilot of the necessity to maintain constant back pressure on the flight controls, enhancing ease of handling.
Aircraft Stability and Performance Characteristics
Inherent Stability: An airplane that is inherently stable will require less effort from the pilot to control.
Longitudinal Stability: This is determined by the specific location of the Center of Gravity (CG) in relation to the center of lift.
Center of Pressure: Changes in the wing's center of pressure affect the aerodynamic balance and controllability of the aircraft.
Aft CG Hazards: If an airplane is loaded with the CG located aft of the aft CG limit, the pilot may experience difficulty in recovering from a stalled condition. Furthermore, an airplane loaded to the most aft CG will be less stable at all flight speeds.
Ground Effect:
Definition: The result of the surface of the earth interfering with the airflow patterns around an airplane.
Occurrence: Floating caused by ground effect is most noticeable during the landing flare when the aircraft is at a height of less than the length of its wingspan above the surface.
Physics: Pilot awareness is crucial because induced drag decreases in ground effect; any excess speed at the point of flare may cause considerable floating. This can lead to the problem of becoming airborne before reaching the recommended takeoff speed.
Turns: The horizontal component of lift is the specific force that makes an airplane turn.
Power Reductions: In aircraft (excluding T-tails), reducing power without adjusting controls causes the nose to pitch down. This happens because the downwash on the elevators from the propeller slipstream is reduced, which in turn reduces elevator effectiveness.
Flight Conditions: Stalls, Spins, and Left-Turning Tendency
Stalls:
As altitude increases, the indicated airspeed at which a given airplane stalls in a specific configuration will remain the same.
An increased load factor (such as in a turn) will cause an aircraft to stall at a higher airspeed.
Spins:
To enter a spin, an aircraft must first be in a stalled condition.
During a spin to the left, both wings are stalled.
Left-Turning Tendencies:
Torque Effect: This is greatest in single-engine airplanes during conditions of low airspeed, high power, and a high angle of attack.
P-Factor (Asymmetric Propeller Loading): This causes an airplane to yaw to the left when at high angles of attack. It results from the propeller blade descending on the right side producing more thrust than the ascending blade on the left side.
Load Factor and Performance Limitations
Load Factor Definition: The amount of excess load that can be imposed on the wing depends upon the speed of the airplane.
Maneuvers: Basic flight maneuvers, specifically turns, increase the load factor on an airplane compared to straight-and-level flight.
Frost:
Frost is hazardous because it spoils the smooth flow of air over the wings, decreasing lifting capability.
On takeoff, frost may prevent the airplane from becoming airborne at normal takeoff speeds due to disrupted airflow.
Pitot-Static System and Flight Instruments
Pitot System: Provides impact pressure specifically for the airspeed indicator.
Instrument Failures from Blockages:
Clogged Pitot Tube: The airspeed indicator will become inoperative.
Clogged Static Vents: The airspeed indicator, altimeter, and vertical speed indicator (VSI) will all become inoperative or affected.
Airspeed Indicator Markings:
Red Line: Represents , the Never-exceed speed.
Maneuvering Speed: This is an important airspeed limitation that is not color-coded on the airspeed indicator.
Altimetry and Altitudes
Definitions of Altitude:
Absolute Altitude: The vertical distance of the aircraft above the actual surface of the earth.
True Altitude: The vertical distance of the aircraft above Mean Sea Level (MSL).
Indicated Altitude: The altitude read directly from the altimeter when set to the local altimeter setting.
Pressure Altitude: The altitude indicated when the altimeter's barometric scale is set to inHg.
Density Altitude: Pressure altitude corrected for nonstandard temperature.
Standard Conditions:
Standard temperature corresponds to a state where pressure altitude and density altitude are the same.
Indicated altitude is the same as true altitude when at sea level under standard conditions.
Pressure altitude equals true altitude when standard atmospheric conditions exist.
Altimeter Setting and Math:
The altimeter indicates true altitude at field elevation when set correctly.
The altimeter-indicated altitude moves in the same direction as the setting and changes at a rate of approximately feet per inHg.
Example 1: Changing the setting from to ( increase) results in a foot increase in indicated altitude.
Example 2: Changing the setting from to ( decrease) results in the altimeter indicating feet lower.
Pressure and Temperature Effects:
Pressure Changes: Moving from low pressure to high pressure without adjusting the altimeter causes the altimeter to indicate lower than the actual altitude above sea level. Moving from high to low pressure causes it to indicate higher than actual.
Temperature Effects: On warm days, pressure levels are raised, and indicated altitude is lower than true altitude. In air colder than standard, true altitude will be lower than indicated altitude.
Magnetic Compass Errors and Operations
Accuracy: Magnetic compass indications are only accurate during straight-and-level, unaccelerated flight.
Deviation: Caused by magnetic fields within the aircraft itself distorting the lines of magnetic force.
Acceleration/Deceleration Errors (Northern Hemisphere):
The compass indicates correctly when on a north or south heading.
Acceleration: While on an east-west heading, acceleration causes a turn indication toward the North.
Deceleration: While on a west heading, deceleration causes a turn indication toward the South.
Turning Errors (Northern Hemisphere):
North Heading: Entering a right turn from a north heading initially indicates a turn toward the West. Entering a left turn from a north heading initially indicates a turn toward the East.
South Heading: Rolling into a standard rate turn to the right from a south heading causes the compass to indicate a turn to the right, but at a rate faster than it is actually occurring.
Engine Operations, Cooling, and Glass Cockpits
Glass Cockpits: These increase situational awareness. Safety requires regular scans of both inside and outside, usage of checklists, and cross-checking information.
Engine Temperatures:
Excessively high temperatures cause loss of power, excessive oil consumption, and potential permanent internal damage.
High oil temperature may be caused by a low oil level.
Air-cooled engines depend heavily on the circulation of lubricating oil for internal cooling.
Indicators of engine overheating include oil and cylinder head temperature gauges exceeding normal ranges, often due to high power and a mixture that is too lean.
Cooling Procedures: To cool an overheating engine during climb, a pilot should reduce the rate of climb, increase airspeed, or enrich the fuel mixture.
Dual Ignition System: Provides improved engine performance and increased safety through redundancy. If the ignition switch ground wire disconnects, the magneto may continue to fire.
Propellers and Fuel Systems
Constant-Speed Propeller:
Controls: The throttle controls power output (Manifold Pressure gauge) and the propeller control regulates engine RPM.
Advantage: Allows the pilot to select the most efficient blade angle for various performance needs.
Precaution: Avoid high manifold pressure settings combined with low RPM.
Carburetor Icing:
Susceptibility: Float-type carburetors are more susceptible to icing than fuel injection systems.
Conditions: Most favorable between and with high humidity.
Indications: In a fixed-pitch propeller aircraft, the first sign is a loss of RPM. Applying carburetor heat will then show a further decrease in RPM followed by a gradual increase.
Fuel/Air Mixture:
Carburetor Heat: Application of heat enriches the fuel/air mixture and generally decreases engine performance.
Altitude Adjustment: The mixture is leaned at altitude to decrease fuel flow and compensate for decreased air density.
Descent: Descending from high altitude ( feet MSL) to lower altitude ( feet MSL) without readjusting the mixture may cause it to become excessively lean.
Abnormal Combustion:
Detonation: The unburned charge in cylinders explodes instead of burning normally. Usually caused by lower-than-specified fuel octane, high-power settings with lean mixtures, or overheating. Initial corrective action: lower the nose to increase airspeed.
Pre-ignition: Uncontrolled firing of the fuel/air charge in advance of normal spark ignition.
Fuel Grade: If the recommended octane is unavailable, the next higher octane aviation gas should be substituted.