11.17 Water And Waste Flashcards
What are the main 3 subsystems in water and waste
- The potable water system
- The waste water system
- The toilet water system
What is the portable water system
The main water supply system on the aircraft and supplies water for the lavatories and galleys
What is the waste water system
The waste water system removes used water from lavatories and galleys and removes it from the aircraft
What is the toilet water system
Removes the waste from lavatories and stores it in tanks
What components does the portable water system consist of
Water storage and distribution, with pressurisation and quantity indication.
The portable water system needs to be serviced
What is the potable water stored in
Water tanks made from glass fibre reinforced plastic
Where are the potable water tanks stored
Located in the pressurised underfloor area of the fuselage
The number of tanks and capacity depends on the aircraft
The water tanks supply water through lines and valves, what are the 2 main valves called
Fill and overflow valve
Manual shut off valves are located in each lavatory
What could be done in the event of a water leak
There are two electrically operated shut off valves that can lock out the front or aft of the aircraft
What components does the lavatory water system have
- 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
Beginning at the tanks where would the water flow in the lavatory water system
From the tanks through the manual shut off valve and then to the header which acts as a distribution point
What does the header distribute water to in the lavatory water system
- The toilet
- The water heater
- The mixer valve via the faucet in the washbasin
With the temperature knob what range of temperature is the temperature range available
From 26-43 degrees c
What are the two ways that the lavatory faucet can be operated
Mechanically or infa red
How does the mechanical faucet work
Push the mechanical actuator and the water will come out
What is the infa red faucet controlled by
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
When will the water stop flowing on the infa red faucet
When hands have been removed and after a pre selected time which can be adjusted between 3-15 seconds
Why does the water heater provide
Hot water to the wash basin in each lavatory
What are the heater tanks controlled/monitored by and what is their capacity
They have electrical heating elements that are controlled by a thermostat
The tank can hold approx 3 pints or 1.5 litres
Wen does the overheat switch activate on the water heater
At around 90 degrees c
What are the 3 preselected temperatures that are available for the water heaters
Low - 38 degrees c
Medium - 44 degrees c
High - degrees c
When does the pressure relief valve open on the water heater
When pressure increases to 140psi or more
It will close again at 130psi
What is used to pressurise water in the potable water system in order to get the water from the tanks to each user
Bleed air from the pneumatic system
If bleed air is not available an electric compressor will be used to produce the flow
What is used in the lines to prevent dirt from the pneumatic system entering the potable water
A filter
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
30psi and will close again when pressure builds up to 40psi
Between the pressure switch and the water storage tanks is a pressure relief valve. At what pressure will this open
60 psi it closes again when it drops below 54 psi
What must be done if a component needs replacing in the potable water system
The system must be depressurised
Where are the potable water service panels located
Usually the lower part of the fuselage and covered by an access door
What does the servicing of the potable water system consist of
Must be filled with the necessary quantity of fresh drinking water and drained of the old water from the tanks when necessary
What are the main components of the water service panel
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
How do you prevent the air compressor from activating during maintenance
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
When filling the potable water system when does the filling stop
When it has reached the preselected quantity which is controlled by the quantity control unit
Why does the quantity transmitter in the tank measure the quantity of the water in the tanks with
A capacitance probe which works in the same way as a fuel quantity probe
Water tanks and water lines for the galleys and lavatories must be drained for maintenance and cleaning purposes how is this done
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
What must be done if the aircraft is being stored outside oversight in freezing conditions
The water system must be drained completely
What are the two sub systems of the waste disposal system
- The waste water system
- The toilet waste system
What is the difference between the waste water system and the toilet waste system
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
How is the flow of the waste water in the water water system through the drain masts and drain lines generated
Gravity and through the differential pressure between the pressurised cabin and the exhaust end of the drain mast
How do the waste water lines and exhaust not freeze
They are heated, the heaters are active as long as the electrical power is on.
What are the two different types of toilet waste system installed in aircraft
Modern aircraft will have a modern vacuum system and older models have flush motor toilets
In a flush motor unit each toilet will have its own unit consisting of what components
- The flushing equipment with flushable handle
- A flush motor assembly
- A waste tank
- The drain equipment
In the flush motor toilet what type of motor is used
A high power three phase electric motor
It is controlled by a timer. It operates by pushing or rotating the flush handle.
How much water flushes the toilet bowl and then returns to the tank?
Around 2 gallons
What does the liquid which flushes the toilet consist of
A chemical mixture of disinfectant, dye and deodorant
How many times can a toilet be used before the tank will need emptying
Around 100 times
How many waste tanks do the vacuum toilets have
Two or more central waste tanks located in the cargo compartment
Size and number depend on the aircraft
What does the vacuum toilet system consist of
A vacuum system, flushing components and components for servicing
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
16,000ft
At an altitude above this the vacuum system is much more efficient
What is the vacuum system connected to the tank via
A liquid or water separator
What is the purpose of the water/liquid separator?
To remove water and waste particles from the waste tank air before venting it overboard
The filters can be changed during system servicing
What is used to gauge the level of the waste in the waste tanks
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
How is the waste from the waste tanks removed
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
What prevents the waste drain cap from leaking waste
There is a safety valve
How must fluid must you use to clean out each waste tank once they have been drained of waste
Between 5 and 10 US gallons depending on aircraft type
For servicing flush motor toilets what is different from the vacuum type
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
