AFS Topic 2 MOD

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Questions and Answers

What is the purpose of venting in a light aircraft fuel tank?

To prevent the tank from collapsing under its own weight (correct)

To heat the fuel before it reaches the engine

To maintain a negative internal pressure

To reduce the fuel capacity of the tank

What is the function of the vent relief valve in a multi-tank fuel system?

To provide venting of the fuel tanks (correct)

To regulate fuel flow to the engine

To mix fuel from different tanks

To cool the fuel before it reaches the engine

What is the purpose of the vent lines at the wing tip in a multi-tank fuel system?

To provide venting to the fuel tanks (correct)

To monitor fuel level

To add fuel to the tank

To remove air from the tank

Why are some vent openings pointed in the direction of flight?

To maintain a positive internal pressure Signup and view all the answers

What is the purpose of the filler cap in an aircraft vent system?

To vent the fuel tank Signup and view all the answers

What is the purpose of the inwards and outwards relief valves in a multi-tank fuel system?

To provide venting to the fuel tanks Signup and view all the answers

What is the purpose of a hole drilled in the fuel cap of a light aircraft?

To vent the fuel tank Signup and view all the answers

What is the purpose of venting in a multi-tank fuel system?

To provide venting to the fuel tanks Signup and view all the answers

What is the purpose of the vent lines in the fuel system?

To draw ambient air to replace fuel that has been removed Signup and view all the answers

What is the function of the fuel heater in the fuel system?

To heat fuel under pressure Signup and view all the answers

What type of instrument is required on all powered aircraft?

Fuel quantity indicator Signup and view all the answers

How do simple float indicators show the fuel level?

By projecting a wire out through the tank filler cap Signup and view all the answers

What is the purpose of the arm-type transmitters in the fuel tank?

To convert float position into resistance Signup and view all the answers

What type of indicator shows the fuel level in discrete amounts?

Elaborate float indicator Signup and view all the answers

What is driven by the float in an elaborate float indicator?

A pointer showing full, ½, ¼ or empty Signup and view all the answers

Where are the fuel quantity indicators typically located?

On the instrument panel in the cockpit Signup and view all the answers

What is the purpose of the refuelling station on an aircraft?

To control the refuelling shutoff valves Signup and view all the answers

What is the primary purpose of a fuel selector valve?

To provide a positive means of shutting off fuel flow and selecting fuel tanks Signup and view all the answers

What happens when the control switch is put to the OPEN position?

The solenoid for the refuelling shutoff valve energizes Signup and view all the answers

What is the purpose of the float switch?

To remove power to the refuelling shutoff valve when the tank is full Signup and view all the answers

Why should seals be lubricated with fuel before installation?

To ensure the seal is compatible with the fuel type Signup and view all the answers

What should be done to the case before fitting a new filter element?

It should be washed out with a suitable approved solvent Signup and view all the answers

What happens when the refuelling shutoff valve is de-energized?

The valve closes Signup and view all the answers

What is the purpose of an interference spider in a non-return valve?

To prevent the valve from being fitted the wrong way round Signup and view all the answers

What do the valve position lights indicate?

That there is power to the refuelling shutoff valves Signup and view all the answers

What should be done after fitting a new filter element?

The engine should be run to pressurize the circuit Signup and view all the answers

What component is used to control the refuelling shutoff valves on some aircraft?

Quantity preselect control Signup and view all the answers

What is the purpose of a non-return valve in a fuel system?

To provide flow in one direction only Signup and view all the answers

What is the purpose of the power control relay?

To energize the refuelling station when the door is open Signup and view all the answers

What is the purpose of the refuelling manifold?

Not mentioned in the content Signup and view all the answers

Where should the fuel selector valve be located in a multi-engine aircraft?

Within easy reach of the pilot Signup and view all the answers

What is the purpose of replacing old seals or gaskets when fitting a new filter element?

To reduce the risk of leakage Signup and view all the answers

What does 'clear' refer to in the context of fuel inspection?

The absence of sediment or entrained water Signup and view all the answers

What is the normal shiny appearance of clean fuel referred to as?

Bright Signup and view all the answers

What may be present in the initial sample taken from an aircraft fuel tank drain point?

A high concentration of water and possibly sediment Signup and view all the answers

Why may the presence of sediment and water in the initial sample be acceptable?

Because the aircraft has been idle for a long enough period to allow water and sediment to settle Signup and view all the answers

What must be done if evidence of sediment is found during fuel sampling?

Investigate to remedy the source Signup and view all the answers

How long should the fuel be allowed to settle before observation during the glass jar method?

1 minute Signup and view all the answers

What is visually inspected for during the glass jar method?

Colour, appearance, and water particulate contaminants Signup and view all the answers

What is the purpose of gently swirling the fuel during the glass jar method?

To create a vortex Signup and view all the answers

Study Notes

Light Aircraft Venting Systems

Vent systems for light aircraft can be simple, consisting of a hole drilled in the fuel cap or a tube running from the top of the fuel tank to the outside of the aircraft.
Some vent systems have vent openings pointing in the direction of flight, maintaining a positive internal pressure inside a bag-type fuel tank.

Multi-Tank Vent Systems

Venting of fuel tanks is provided through inward and outward relief valves.
Vented air flows in and out through vent ports at the wing extremities.

Fuel Valves

Fuel selector valves (also called fuel cocks) provide a positive means of shutting off fuel flow, selecting the tank in a multiple-tank installation, transferring fuel from one tank to another, and directing fuel to one or more engines in a multi-engine aircraft.
Non-return valves may be fitted in several places in the fuel system to provide flow in one direction only.

Fuel Quantity Indicating Systems

Float indicators show the relative amount of fuel in the tank, with no requirement for calibration in discrete amounts.
Elaborate indicators have the float drive a pointer that shows whether the level of fuel in the tank is ¼, ½, ¾, or full.
Electrical ratiometer converts the position of a float into resistance, driving fuel quantity indicators located on the instrument panel.

Pressure Refuelling System

On large aircraft, fuel tanks are filled from the refuelling station at the right wing.
The refuelling station has components such as a refuelling panel, manifold, receptacle, and shutoff valves.
The refuelling station permits control of the refuelling shutoff valves, with automatic control through a quantity preselect control and manual control as a backup.

Fuel Quality and Testing

Fuel samples should be clear, with no visible sediment or entrained water, and bright, with a normal shiny appearance.
Water contamination can be detected using water test kits, such as the glass jar method or the Shell water detection kit method.
Sampling must continue until the fuel sample meets specified requirements of purity, and evidence of sediment must be investigated to remedy the source.

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Description

Learn about the light aircraft venting systems, including simple designs like holes in fuel caps or tubes from the top portion of the tank.