A330 Water Dump During Startup
 

Hi everyone,

Whilst taken a well earned break from my CPL training, I spent an evening up at Auckland airport as they've a great viewing area by the runway.

During engine start on an China Southern A330-200 I noticed a hell of a lot of liquid being dumped from what appeared to be the underside of the fuselage.

We were pretty intrigued as to what it was (probably water?) and why it was being dumped, so I thought I would ask if anyone had a clue? I've never seen this before...

Many thanks!

Air conditioning water?
 

I can't speak for the A330, but the 737 - certainly the versions that I flew - dumps the water from the air conditioning humidity separator from a vent in the fuselage underside. This was adjacent to the front steps, which was disconcerting for the boarding passengers, who often reported to the cabin crew that we seemed to have a fuel leak and wasn't 'The Pilot' worried about it!

:)

Could it possibly be the distilled water used for injection into the compressor when operating in "hot and high" mode?

The water you see just before start up is running out of the aircon pack ram air inlets when the packs are shut down for engine start:

1 - When the packs are in operation, water is separated out of the bleed air passing through them, & is then sprayed into the ram air inlet duct, where it cools the primary heat exchanger, thereby increasing its effect.

2 - When the engines are started, the aircon packs are switched off so that bleed air (from the APU) is sufficient to crank the engine over.

3 - With the pack(s) off, there is no longer any airflow through the ram air duct & water runs out of the front of it under gravity.

Often reported as a fuel leak by new pushback crews.

Could be grey water. It goes overboard though drain masts on the belly.

Nowaday, we don't use de-min water to boost take off power like BAC1-11.

If it came out from the belly drain mast, take a cup full to drink as it was a mixture of cocktail dumped by galley crews after serving pax before push back.

Most likely it was from the aircon packs which you could drink but not as fresh as mineral water.

Like so: Photos: Airbus A330-202 Aircraft Pictures | Airliners.net

As already stated it is water from the pack water seperators that is normally injected into the ram air system when operating. When the packs are off it runs forward out of the ram inlet door. Years ago when we used to push the MD-11 back with an open-cab tug in a left turn it was affectionately known as a "Pack 3 Shower"

Great! Thanks for your replies, mystery solved!