13.19 Water/Waste

Question 1

Define potable water?

Answer 1

Water fit for drinking

Question 2

What materials are water tanks made of?

Answer 2

Fibre–glass reinforced plastic

Stainless steel used in older aircraft

Question 3

How might the tanks be heated?

Answer 3

Warm air from the air conditioning system

Electric heater blanket

Question 4

What is the purpose of the compressor?

Answer 4

Automatically start when the pneumatic pressure falls below a predetermined value

Question 5

Why would a riser loop be fitted with a compressor and how is this achieved?

Answer 5

Prevent water entering the compressor

Top of the loop is higher than the distribution ducting therefore water will always go to the distribution lines first

Question 6

Why are the plastic water distribution pipes shrouded inside aluminium pipes?

Answer 6

Outer shroud prevents leaking water dripping onto the ceiling and conveys any leaking water to the lower fuselage area via drain tubes

Question 7

What indication is there that the water heater is operating normally?

Answer 7

Heater switch will be on and a light will illuminate

Question 8

What is the normal cycling temperature for the heater?

Answer 8

50°C

Question 9

What is the overtemperature trip temperature for the heater and what will happen at this temperature?

Answer 9

90°C

Overheat switch will operate

Switch off the heater and the light

Question 10

Explain the drain mast heater system?

Answer 10

115v AC in air

28v DC on ground

Changeover controlled by WOW switch

Question 11

What is the water replenishment pressure range?

Answer 11

Generally above 25 psi

Maximum of 55 psi

Question 12

What must be carried out after disinfecting the water system?

Answer 12

The system is emptied and refilled with chlorinated water

Question 13

In the toilet tank, how much disinfectant solution is replenished following toilet emptying?

Answer 13

5 gallons

Question 14

How is the filter prevented from becoming blocked on each flush cycle?

Answer 14

Motor will reverse its direction to prevent the rotating filter mesh becoming entangled with non–decomposable waste

Question 15

What governs the level of filtration in a disc type filter?

Answer 15

This type of filter consists of a stack of flat wheel shaped discs, each disc separated by a spacer

The thickness of the spacer holding the discs apart determines the degree of filtration

Question 16

What might cause overheating of the motors and therefore tripped CBs or fuses?

Answer 16

Overheating could be caused by failure of:

Control circuit
Control circuit components
Motor
Pump

Question 17

How is the inside of a liquid flush tank cleaned?

Answer 17

A perforated tube called a flush line

Fitted around the top of the waste tank on the inside

Clean the sides of the tank when the chemical is replenished through the ground flush line, after the tank is emptied

Question 18

At what altitude will the blowers of vacuum flush system cut out?

Answer 18

Above 16,000 feet

Question 19

When would a ‘Y’ coupling be used?

Answer 19

When a waste line rubber bung is fitted

Question 20

What is the purpose of the venturi in the galley and toilet ventilation system?

Answer 20

Limits the outflow of cabin air when the aircraft is pressurised

Question 21

How often must toilet waste containers be inspected?

Answer 21

At intervals not exceeding 72 hours elapsed time

Question 22

What position must the waste container flap default to?

Answer 22

Spring loaded closed, sealed and latched

Question 23

At what temperature will the automatic fire extinguisher fusible plug within the waste container melt?

Answer 23

175°F
80°C approximately

Question 24

How is drain flow assisted in the waste water drain system?

Answer 24

System uses the difference between cabin pressure and external pressure in flight to help push fluids through the tubing as well as relying on the normal forces of gravity

Question 25

What are installed in the waste water drain system to catch debris that is inadvertently flushed down galley sinks and prevent it from clogging the drain further downstream?

Answer 25

Galley sink strainers

Question 26

For how many uses will a typical charged liquid flush toilet last for before it requires to be emptied, cleansed and recharged?

Answer 26

One hundred usages

Question 27

What is differential pressure used for in the typical vacuum flush toilet?

Answer 27

Used to evacuate the air from the waste tanks