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Old 9th Dec 2012, 03:22
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Flatface
 
Join Date: Jun 2005
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There are many reasons why a coffee maker will not brew. Frozen water in the pipes is one reason, slush too can block the lines.

You need many things to happen for the coffee maker to work. Power, if the utility buss (can be switched off in the flight deck) or external power can trip off no coffee. If you do have power, if there is no water in the coffee maker, usually, there is a light on the coffee maker warning of no water. There is also over heat protection built into the coffee maker, much like your coffee maker at home, if the coffee maker is empty, it may trip the overheat protection and the coffee maker will not work. Unlike you coffee maker will not reset on it's own. Someone will have to remove the coffee maker and reset the overheat protection switch.

With no APU or engines running there is no air pressure to the water tank, the water tank needs air pressure to pressurize the tank to push the water through the pipes to the coffee maker.

The water lines between the coffee maker and water tank, usually below the floor, could be empty. So if the lines are empty, you will need to hold the water faucet open until the water from the tank, being pushed by the air pressure on top of the water inside the tank travels through the lines to the coffee maker. Further, even if the APU is running or the engines are running, if he water lines are empty, the air in the lines has to be bled out before the coffee maker will work. The air will prevent the water from flowing unless there is opening for the air to escape, usually the faucet. If you hold down the faucet, you should here the air escaping, this is a good sign and if you are patient and continue to hold the faucet open, the water will eventually arrive.

A good example if this is when you buy a new garden hose. You hook up one end of the garden hose to the water faucet, when you turn on the spray nozzle at the other end of the brand new hose, you do not get water coming out of the hose immediately. You must hold the water nozzle open until the water pressure pushes all the air out of the new hose before the water will flow.

All these instructions are assuming that the water system is intact and serviceable.

Pipes do freeze, even if the pipes have heating ribbons installed, this system is not perfect and sometimes gets disturbed during maintenance. The pipes can burst and do occasionally.

Anytime you are outside the aircraft in freezing weather, look at the fuselage bottom at the 6 o'clock position, if there are icicles hanging from the fuselage drain valves, these will close once the fuselage is pressurized, you can be almost sure that a water line is leaking or worse, burst from freezing.

If this happens close to departure time, we would usually deactivate and drain the water system, we then call for bottles water and hand wipes for the lavs. We would also call the kitchens to supply thermos' full of coffee. Not too many airlines want to take a delay for this. This will continue all day until the next hangar visit, hopefully the aircraft is rerouted to a hangar layover to repair this.
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