earthman wrote:In some of the pictures you can see fire crews spraying 'nasty brownish stuff' into the #1 engine, I assume that is to shut it off.
Do the fire trucks at that airport double as waste water disposal trucks?
The "nasty brownish stuff" is actually water mixed with an (ATC / AR-AFFF) foam product, probably in a 3 to 6% mix.
ATC foams like AR-AFFF are used to extinguish so called "Class B" fires (flamable liquids) (but works also on Class A fires) and are also used to prevent flamable liquids like JET-A1 for example to ignite. When you lay a layer of foam over something that contains flamable liquids then the foam prevents the ignition of the liquids.
Depending on the type of incident a mixture is chosen, most of the fire trucks who use foam have those days a foam mixing device installed on the pump and either through a manual selection or a digital computer based setup you can chose the percentage of foam product being used. This can vary between as less 0,3% to as much as 6%. So when you use a mixture of 3% (common with AFFF) then you'll use 3 litres of foam for 100 litres of water.
The newer types of foam doesn't color and you'll get nice white foam those days. The picture of Singapore however reminds me to the older foamproducts of 3M which did indeed color brown.
So no, fire trucks aren't using disposal water
While foam is rather harmless there is some side effect, AFFF causes corrossion so since they started to drown the engine with it I'm pretty sure that the nr1 engine is ruined by the foam even though they switched over to plain water afterwarts (the drowning was intended to stop the engine)
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