Commercial Pilot Ground School Overview

Commercial Pilot Ground School

• This course outlines the ground school curriculum for Commercial Pilot License (CPL) Aircraft Engineering Systems (AES).
• The course covers Airframes, Engines, and Systems.

Course Outline

• Class 1: 96 slides covering Methods of Construction, Landing Gears, Brakes, Flaps, and Engines
• Class 2: 112 slides covering Carburation, Fuel Injection, Electrical System, Lubrication Systems and Oil, and Fuel Properties and Fuel Systems
• Class 3: 72 slides covering Other Aircraft Systems, Turbochargers and Superchargers, Jet Engines (Turbines), Oxygen and Pressurization, and Anti-Ice and De-Ice Systems
• Class 4: Final Exam and Review: 50 multiple-choice questions in 1 hour, plus a 1-hour review session, all on the same day as the final exam.

Important Information - CPL AES

• The CPL AES curriculum builds upon the knowledge learned in PPL ground school, focusing on high-performance aircraft systems.
• Required self-study: Students must review notes, supplement them with textbook and workbook materials, and utilize available online interactive videos.
• Course expectations: Punctuality, adherence to uniform requirements, and preparation with necessary supplies. Penalties for non-compliance are noted.
• Additional reference material like Ground School slides, workbook materials, and study guides are provided.

Today's Pilot

• Today's pilot is a systems manager, requiring in-depth knowledge of the components and systems of the aircraft.

Methods of Construction

• Truss Type: Wood or steel tubing, strong, non-load-bearing skin (fabric or plywood).
• Monocoque Type: A monocoque or stressed-skin construction is often used, comprising aluminum or composites. The skin bears the load, with extra internal bracing sometimes called semi-monocoque.

Materials Used in Construction

• Aluminum alloy: Durable, resists weathering, light, strong, ideal for assembly by semi-skilled personnel, and has extensive design data.
• Wood: Flexible, light, and strong, but labor intensive for construction, and difficult to acquire in suitable lengths. Typically used with modern epoxy resins.
• Composites: Made from fiberglass, kevlar, carbon, and/or graphite embedded in epoxy, polyester, or vinyl ester resin. These materials are light, strong, and provide smooth surfaces, making them ideal for compound curves.

Fiber-Glass Composite

• This material constructs an aircraft in layers of high-strength exterior skin materials separated by a lightweight core material (ex: PVC, Styrofoam, end grain balsa wood, Nomex, or aluminum honeycomb).

Wheel Arrangement

• There are three common wheel arrangements on aircraft: Tail Wheel (conventional gear), Tricycle (trike gear), and Tandem.
• The tailwheel gear is commonly used for rough field landings, while the tricycle gear is more common due to superior ground handling. Tandem gear is rarely used.

Types of Fixed Gear

• Single Leaf Cantilever, Single strut, Tripod, and Split Axle Shock Cord descriptions and examples are introduced.

The Oleo

• Used to absorb landing shocks. The shock absorption is achieved via oil forced through a hole.
• Springs or compressed air can be added for ground taxiing shock absorption. Compressed air is sometimes replaced with nitrogen to prevent corrosion.

Retractible Landing Gear

• More sophisticated aircraft have retractable landing gear, controlled by the pilot.
• Although advantageous aerodynamics, complexity, cost, and potential for landing with gear up is noted.

The Brakes

• Good brakes are required for reliable quick deceleration and steering on the ground.
• Mechanical, Hydraulic, and Pneumatic brake actuation are detailed. Electrical brake actuation involving a screw jack that controls the landing gear is also discussed.
• The hydraulic brake fluid is often dyed red for easy leak detection. Some aircraft have anti-skid brake systems that are complex electro-hydraulic devices.

Flap Actuation

• Many light aircraft use strictly mechanical flap actuation, using levers, pushrods, and bell cranks.
• Hydraulic and electric motors systems are sometimes used for more complex linkages.

Engine Cylinder Layouts

• Horizontally Opposed: Most common in light aircraft due to good visibility, low parasite drag and lower cost. Lycoming and Continental are prominent manufacturers.
• Radial Engine: Known for robustness, reliability, but with high parasite drag and poor visibility. Pratt & Whitney and Curtis-Wright were notable manufacturers, but radial engines are rarely used today.
• In-line Engine: Offers good drag and visibility characteristics. Typically limited by cylinder count due to vibration. Some British manufacturers produced in-line engines, including the "Gypsy Queen".

Engine Power

• Piston engines are rated in horsepower, power is the rate of doing work, one horsepower is the amount of work done when 33,000 pounds are raised one foot in one minute.
• Brake horsepower is the output after friction and other losses. Jet engines are rated in pounds of static thrust. Indicated horsepower is the amount of horsepower developed within an internal combustion engine and is equal to PLAN/33,000.

The 4 Stroke Cycle

• The four strokes—intake, compression, power, and exhaust—are detailed for piston engines.

The Two Stroke Cycle

• Two-stroke engines are powerful but not as fuel-efficient, often found in small equipment.

Valve Overlap

• Valve overlap, where intake and exhaust valves open simultaneously, is a feature of some engines, though counter-intuitive. The inertia of the gases aids fill the cylinder.

Methods of Engine Cooling

• Air Cooling: Uses fins on barrels and cylinder heads, aided by baffles in the cowling. Exhaust augmentor tubes can enhance cooling. Oil cooling is also common.
• Oil Cooling: The oil coolant helps to cool air-cooled engines.
• Liquid Cooling (Water Cooled): Water jackets surround the heat-producing parts of the engine, often with a pump and radiator, to enhance fuel efficiency.

The Ignition System

• The ignition system provides the spark for igniting the fuel/air mixture. A magneto, an engine-driven generator, produces the alternating current, utilizing a permanent magnet as its power source. It contains two magnetos, two spark plugs in each cylinder, ignition leads, and a magneto switch. Magneto principles, polarity, and types (rotating armature and rotating magnets) are explained. A condenser in the system reduces current jumping between components. Impulse coupling facilitates rapid starting.

Dual Ignition

• Most aircraft use dual ignition systems (two magnetos per engine) for improved safety and performance.

Full Authority Digital Engine Control (FADEC)

• A computer system managing engine and ignition control.

Exhaust Systems

• Spent gases (including carbon monoxide) are expelled from the aircraft through exhaust systems. These systems are typically made of stainless steel for strength and light weight.Mufflers reduce noise.

Ancillary Controls

• Carburetor Heat Control - Used to heat the air/fuel mixture before entering the carburetor to prevent ice formation.
• Primer Pump - Provides a means to introduce raw fuel to the intake ports during cold starts.
• Mixture Control - Allows the pilot to adjust the fuel-air mixture ratio.
• Alternate Air - Provides a backup in case the normal air inlet is blocked for various reasons, especially icing.
• Cowl Flaps - Used to help control engine cooling and temperatures.
• Environmental Controls - Include cabin heating and windshield defogging.

Effects of Density Altitude, Humidity, and Power

• Outside air temperature and altitude affect engine power output. Higher density altitude results in better engine performance, and density altitude values are helpful in making fuel/payload calculations. Humidity slightly decreases engine performance.

Limitations and Operations

• Operating procedures like slow throttle openings and avoiding high-speed dives, prolonged idling, that creates overheating, is essential, particularly if the engine is equipped with an idle cut-off.

Engine Instruments

• Engine instruments offer critical operative and performance data.
• Oil Pressure Gauge: Monitors the oil pressure produced by the pump during operation.
• Oil Temperature Gauge: Measures the oil temperature, providing an indication to the pilot regarding adequate operation and safety.
• Fuel Pressure Gauge: Shows the pressure produced by the fuel pump; helpful for low-wing aircraft but redundant in high-wing aircraft due to gravity-fed systems.
• Tachometer: Shows revolutions per minute of the engine. This is helpful with constant speed props.
• Carburetor Air Temperature: Indicates the temperature of the fuel-air mixture.
• Exhaust Gas Temperature: Measures the temperature of exhaust gases.
• Suction Gauge - shows the vacuum system.
• Manifold Pressure Gauge: Shows fuel-air pressure and is used with RPM to define power settings.

The Diesel Engine

• Diesel engines operate on similar principles to gasoline engines but ignite the fuel-air mixture through extreme compression instead of electrical sparks.
• Compression rates are generally higher and operate at higher temperatures than gasoline engines.

Fuel Types

• Common aircraft fuels are AVGAS (aviation gasoline), jet fuel, and MOGAS (automotive gasoline).
• Fuel is graded based on octane ratings and color coding. Different fuel types are specific to different engine types and characteristics.

Fuel Icing

• Icing occurs when water droplets in the air turn to ice, which can block the fuel lines and potentially result in engine failure.

Fuel System Components

• Fuel tanks and locations (wing tanks, extra tanks in cabin) - Venting of fuel tanks and baffling of fuel tanks to prevent fuel sloshing.
• Fuel lines and associated components (filters, lines, etc.) are present.

The Induction System

• The induction manifold distributes the fuel-air mixture to each cylinder(s). The system requires that air converts the liquid fuel into a gaseous form for combustion.

Detonation

• Detonation occurs when the rate of combustion of fuel is abnormal and exceeds the structural limits of the piston engine. Slow combustion is preferred.
• Causes of detonation include incorrect fuels, low octane blends, too lean mixtures, excessive boost or manifold pressure, and overheating from prolonged climbs at best angle.
• The remedy is often throttle reduction, while correcting fuel grade is a permanent solution. This problem can be identified by a rapidly rising temperature gauge related to the cylinder head.

Pre-Ignition

• Pre-ignition is the premature ignition of the fuel-air mixture. It is often present during engine starts on hot engines. Pre-ignition is caused by carbon particles glowing.
• Pre-ignition is addressed through correct maintenance procedures to avoid very high temperatures in the cowling.

Vapor Lock

• Vapor lock occurs when high temperatures cause fuel to vaporize excessively, blocking the fuel flow. Low-pressure related or high-altitude situations may also induce vapor lock.
• Use of proper grades of fuel and a fuel boost pump may help prevent this.

Fuel Heater

• Fuel heaters are used to prevent icing by heating the fuel. Two types are—Air-to-Liquid and Liquid-to-Liquid

Primers

• The primer pump is used to introduce fuel into the engine intake. This is typically required at very low temperatures. Correct use and cautions must be observed for the primer. Inaccurate use can lead to engine fires.

Fuel Management and Safety

• Proper fueling procedures are necessary for the safety of the aircraft and personnel (no smoking).
• It is the pilot's responsibility to ensure the aircraft is fueled correctly with fresh fuel, and to avoid any contamination.

Grounding and Bonding

• Grounding and bonding are crucial in aircraft electric systems to prevent static charges caused by air and refueling which can potentially cause fuel fires.
• Static discharge wicks, ground wires, and other safety instruments are used.

Other Aircraft Systems

• Turbocharging: Turbochargers increase air density, allowing for higher engine power at high altitudes. The boosted pressure is referred to as "boost".
• Fuel Injections: The fuel injection system meters fuel to each cylinder independently to produce slightly more power and less fuel than a carburetor system.
• Jet Engines: Jet engines operate on different principles. Air is compressed and burned with fuel to create thrust. Methods of classifying various jet types and compressor systems (axial and centrifugal) are covered.
• Jet Combustion Chambers: This section details the design and functionalities like can, can-annular, and annular types used in the jet engines.
• **Jet Turbines:**These components use exhaust gas to drive compressors and other accessories.
• Thrust & Engine Health Measurements: This sections details the key indicators like Engine Pressure Ratio measurement and the N1 and N2 measures which are specific to jet engines. Information on Turbine Classification and the various types of propeller-driven systems and configuration is also covered.
• Oxygen System: Oxygen systems for aircraft are discussed to address hypoxia conditions, highlighting the importance of supplemental systems and operation at high altitudes, utilizing types and configurations.
• Vacuum Systems: Types of vacuum systems are explained in detail. Those include the venturi driven vacuum systems and their functions are explained.
• Environmental Systems (Pressurization + AC): This covers cabin heating and pressurization, including the roles of the devices involved like pressure regulators, and safety measures to maintain and control cabin temperature.