water feezing in fuel lines?
I was lucky to be trained as a flight engineer many years ago.
We we taught to suspect everything if we had a fault in our aircraft.
We flew with it for up to 14 hrs on maritime reconnaisance out over the north Atlantic. It was MY responsibility to see we got where the navigator took us and get it back!!.
no mean task for a 20 yr old.
So, I still follow aviation news and this incident made me think, what set of conditions could cause fuel starvation after this uneventful flight?.
well, based on the facts as first reported by the AAIB, they flew through an area of extreme cold, this on its own isnt a problem with fuel flow to the engines as the fuel would be at a much higher temperature than the outside air, and even if the airframe in the wings was reduced to -70c the fuel would keep the pipe temperature up above the freezing point of any water in the fuel or the fuel itself.
BUT what happens when you throttle back to make the rapid decent from 40.000ft over the North sea? your fuel flow will drop very considerably in an airframe that still might be -70c.
Any water in the fuel will then have the chance to be cooled to below freezing inside the fuel pipes and thus restrict the fuel flow, as well as the possibility of the fuel freezing as well.
This doesnt matter when the engines are in descent mode, but the moment you want power to correct the landing glide path then opening the throttles to call for more fuel, wont happen, because the fuel flow may well have been restricted by ice or fuel slush like diesel fuel in winter..
By the time the AAIB got to work on the airframe it would have regained its normal temperature and the ice/fuel would have melted.
Especially as there was a fuel leak and any water residue may have spilled out.
Now they say the ambient air temp wasnt as low as -70c but much less.
So my initial thoughts now seem unfounded.
I commented to aviation frends one would need to replicate fuel flows in the temperature gradients they experienced to see if the fault could be duplicated.
Just an old engineer not a bold engineer.
269 Sqn RAF.