11.17 Water And Waste

Question 1

What are the main 3 subsystems in water and waste

Answer 1

• The potable water system
• The waste water system
• The toilet water system

Question 2

What is the portable water system

Answer 2

The main water supply system on the aircraft and supplies water for the lavatories and galleys

Question 3

What is the waste water system

Answer 3

The waste water system removes used water from lavatories and galleys and removes it from the aircraft

Question 4

What is the toilet water system

Answer 4

Removes the waste from lavatories and stores it in tanks

Question 5

What components does the portable water system consist of

Answer 5

Water storage and distribution, with pressurisation and quantity indication.

The portable water system needs to be serviced

Question 6

What is the potable water stored in

Answer 6

Water tanks made from glass fibre reinforced plastic

Question 7

Where are the potable water tanks stored

Answer 7

Located in the pressurised underfloor area of the fuselage

The number of tanks and capacity depends on the aircraft

Question 8

The water tanks supply water through lines and valves, what are the 2 main valves called

Answer 8

Fill and overflow valve

Manual shut off valves are located in each lavatory

Question 9

What could be done in the event of a water leak

Answer 9

There are two electrically operated shut off valves that can lock out the front or aft of the aircraft

Question 10

What components does the lavatory water system have

Answer 10

• A header that distributes the water
• A manual shut off valve that is for isolating the lavatory from the water supply if there is a leakage
• A water heater that heats the water
• A mixer valve for mixing hot and cold water
• A wash basin with faucets

Apart from the wash basin all of the components are found in the cabinet beneath the sink

Question 11

Beginning at the tanks where would the water flow in the lavatory water system

Answer 11

From the tanks through the manual shut off valve and then to the header which acts as a distribution point

Question 12

What does the header distribute water to in the lavatory water system

Answer 12

• The toilet
• The water heater
• The mixer valve via the faucet in the washbasin

Question 13

With the temperature knob what range of temperature is the temperature range available

Answer 13

From 26-43 degrees c

Question 14

What are the two ways that the lavatory faucet can be operated

Answer 14

Mechanically or infa red

Question 15

How does the mechanical faucet work

Answer 15

Push the mechanical actuator and the water will come out

Question 16

What is the infa red faucet controlled by

Answer 16

A reflective sensor unit with 2 lenses

When water is required the reflective sensor opens a solenoid operated shut off valve on the mixer valve

Question 17

When will the water stop flowing on the infa red faucet

Answer 17

When hands have been removed and after a pre selected time which can be adjusted between 3-15 seconds

Question 18

Why does the water heater provide

Answer 18

Hot water to the wash basin in each lavatory

Question 19

What are the heater tanks controlled/monitored by and what is their capacity

Answer 19

They have electrical heating elements that are controlled by a thermostat

The tank can hold approx 3 pints or 1.5 litres

Question 20

Wen does the overheat switch activate on the water heater

Answer 20

At around 90 degrees c

Question 21

What are the 3 preselected temperatures that are available for the water heaters

Answer 21

Low - 38 degrees c
Medium - 44 degrees c
High - degrees c

Question 22

When does the pressure relief valve open on the water heater

Answer 22

When pressure increases to 140psi or more

It will close again at 130psi

Question 23

What is used to pressurise water in the potable water system in order to get the water from the tanks to each user

Answer 23

Bleed air from the pneumatic system

If bleed air is not available an electric compressor will be used to produce the flow

Question 24

What is used in the lines to prevent dirt from the pneumatic system entering the potable water

Answer 24

A filter

Question 25

At what pressure does the pressure switch open if the pneumatic system isn't providing enough air and requires the electric motor to kick in

Answer 25

30psi and will close again when pressure builds up to 40psi

Question 26

Between the pressure switch and the water storage tanks is a pressure relief valve. At what pressure will this open

Answer 26

60 psi it closes again when it drops below 54 psi

Question 27

What must be done if a component needs replacing in the potable water system

Answer 27

The system must be depressurised

Question 28

Where are the potable water service panels located

Answer 28

Usually the lower part of the fuselage and covered by an access door

Question 29

What does the servicing of the potable water system consist of

Answer 29

Must be filled with the necessary quantity of fresh drinking water and drained of the old water from the tanks when necessary

Question 30

What are the main components of the water service panel

Answer 30

A T handle, a fill fitting with a protective cap, a water quantity indicator and an air compressor interlock switch There is also a drain valve handle and a drain port

Question 31

How do you prevent the air compressor from activating during maintenance

Answer 31

When the service panel door is opened the interlock switch is activated preventing compressor operation during servicing The switch is a magnetic reed switch also known as a proximity switch

Question 32

When filling the potable water system when does the filling stop

Answer 32

When it has reached the preselected quantity which is controlled by the quantity control unit

Question 33

Why does the quantity transmitter in the tank measure the quantity of the water in the tanks with

Answer 33

A capacitance probe which works in the same way as a fuel quantity probe

Question 34

Water tanks and water lines for the galleys and lavatories must be drained for maintenance and cleaning purposes how is this done

Answer 34

Drain valves and shut off valves are used to drain all of the water. The drain valves are operated manually Normally it is required to force the water out of the drain valve by using APU bleed air

Question 35

What must be done if the aircraft is being stored outside oversight in freezing conditions

Answer 35

The water system must be drained completely

Question 36

What are the two sub systems of the waste disposal system

Answer 36

- The waste water system | - The toilet waste system

Question 37

What is the difference between the waste water system and the toilet waste system

Answer 37

The waste water from the waste water system is drained out through drain lines and drain masts whereas the toilet waste is collected in designated tanks

Question 38

How is the flow of the waste water in the water water system through the drain masts and drain lines generated

Answer 38

Gravity and through the differential pressure between the pressurised cabin and the exhaust end of the drain mast

Question 39

How do the waste water lines and exhaust not freeze

Answer 39

They are heated, the heaters are active as long as the electrical power is on.

Question 40

What are the two different types of toilet waste system installed in aircraft

Answer 40

Modern aircraft will have a modern vacuum system and older models have flush motor toilets

Question 41

In a flush motor unit each toilet will have its own unit consisting of what components

Answer 41

- The flushing equipment with flushable handle - A flush motor assembly - A waste tank - The drain equipment

Question 42

In the flush motor toilet what type of motor is used

Answer 42

A high power three phase electric motor It is controlled by a timer. It operates by pushing or rotating the flush handle.

Question 43

How much water flushes the toilet bowl and then returns to the tank?

Answer 43

Around 2 gallons

Question 44

What does the liquid which flushes the toilet consist of

Answer 44

A chemical mixture of disinfectant, dye and deodorant

Question 45

How many times can a toilet be used before the tank will need emptying

Answer 45

Around 100 times

Question 46

How many waste tanks do the vacuum toilets have

Answer 46

Two or more central waste tanks located in the cargo compartment Size and number depend on the aircraft

Question 47

What does the vacuum toilet system consist of

Answer 47

A vacuum system, flushing components and components for servicing

Question 48

Below what altitude does it require for a pressure switch to activate the vacuum blower to then reduce the tank pressure for the toilet to be flushed

Answer 48

16,000ft At an altitude above this the vacuum system is much more efficient

Question 49

What is the vacuum system connected to the tank via

Answer 49

A liquid or water separator

Question 50

What is the purpose of the water/liquid separator?

Answer 50

To remove water and waste particles from the waste tank air before venting it overboard The filters can be changed during system servicing

Question 51

What is used to gauge the level of the waste in the waste tanks

Answer 51

A level sensor, there is also another sensor if the first one fails Sometimes they have an independent transmitter that controls a level indication on the attendants panel

Question 52

How is the waste from the waste tanks removed

Answer 52

Via the central waste panel located on the bottom of the fuselage There is one drain fitting for each tank, there is also a ground flush line to clean the tanks

Question 53

What prevents the waste drain cap from leaking waste

Answer 53

There is a safety valve

Question 54

How must fluid must you use to clean out each waste tank once they have been drained of waste

Answer 54

Between 5 and 10 US gallons depending on aircraft type

Question 55

For servicing flush motor toilets what is different from the vacuum type

Answer 55

On the flush motor toilets they have a designated tank per toilet whereas the vacuum system have large tanks in the cargo bay which collects the waste from all the toilets