ATA 28 - Aircraft Fuel Systems Quiz

Fuel System

• Fuel tanks are located inside the aircraft structure and have inspection panels for internal inspection, repair, and servicing.
• There are two types of fuel tanks: integral and bladder.
• Integral fuel tanks are areas inside the aircraft structure that have been sealed to allow fuel storage.
• Bladder fuel tanks are reinforced rubberized bags installed in a section of aircraft structure designed to accommodate fuel.
• Fuel pumps deliver a properly pressured, continuous supply of fuel and may be driven manually, electrically, or engine-driven.
• Fuel gauges indicate the amount of fuel measured by a sensing unit in each fuel tank and are displayed in gallons or pounds.
• Valves are installed in the fuel system to provide a means for shutting off the fuel flow, for tank and engine selection, for crossfeed, and for fuel transfer.
• Fuel primers are used to draw fuel from the tanks to vaporize fuel directly into the cylinders prior to starting the engine.

Fuel Types

• There are two main types of fuel: AVGAS and Jet Fuel.
• AVGAS is a gasoline-based fuel that is better suited for cold weather and has more energy per weight.
• Jet Fuel is a kerosene-based fuel that is more volatile and has a higher sulfur content.
• AVGAS 80 is a mixture of 80% iso-octane and 20% heptane.
• AVGAS 100 is a high-octane fuel with anti-knock properties.
• AVGAS 100LL is a low-lead version of AVGAS 100.
• Jet A has a freeze point of -40°F (-40°C).
• Jet A-1 has a freeze point of -52.6°F (-47°C).
• Jet B is a mixture of gasoline and kerosene with a freeze point of -58°F (-50°C).

Hydraulic System

• The hydraulic system operates on the principle of Pascal's Law (F1 = F2, P1A1 = P2A2).
• The hydraulic system has several advantages, including the ease of transmitting force over large distances and achieving mechanical advantage.
• Hydraulic fluid must be able to flow through all of the lines with a minimum of opposition, and it must be incompressible.
• Hydraulic fluid must also have good lubricating properties to prevent wear in the pump and valves.

Flight Controls

• The primary purpose of the aircraft fuel system is to supply fuel to the engines and APU, control and monitor the correct quantity of fuel, and control the transfer of fuel to maintain within C.G limits.
• The secondary purpose of the fuel system is to keep fuel in the outer wing for wing bending and flutter relief, and to cool oil inside the engine.
• Airplane axes of rotation include the longitudinal axis (roll), lateral axis (pitch), and vertical axis (yaw).
• Primary flight controls include ailerons, elevators, and rudders.
• Secondary flight controls include flaps, trim tabs, and spoilers.

Flight Control Surfaces

• Ailerons control roll about the longitudinal axis.
• Elevators control pitch, the up-and-down motion of the aircraft's nose.
• Rudder controls yaw, the rotation of the aircraft's nose left or right.
• Flaps are located on the inner portion of the wing and increase the wing's lift for takeoff and landing.
• Types of flaps include plain, split, slotted, and Fowler flaps.
• Trim tabs are small movable portions of the trailing edge of a control surface that reduce the stick forces or control forces.
• Balance tabs and anti-servo tabs are used to aerodynamically assist in moving control surfaces.
• Ground adjustable tabs are bent in one direction or the other while on the ground to apply a trim force to the rudder.
• Trimmable horizontal stabilizers are used to adjust the pitch of the aircraft.