Lurkio, I think the article referenced by Turn and Slip provides a better explanation.
It states that the two causes of increased consumption caused by increasing drag are failures affecting the landing gear or landing gear doors, or failures affecting the flight control surfaces.
it elaborates on this last point-
Three specific flight control configurations create a differing amount of drag
1-The surface is blocked in the fully deflected position.
2-The surface is free and floats in the wind
3-The surface(spoilers only) slowly extends over time.(floats). This can be caused by a hydraulic or electrical failure.
DC Ess bus (spoiler3) is powered from DC Bat bus and hence from BAT1 and I think from reading the footnotes that this spoiler will float when it is no longer electrically supplied , leading to a corresponding increase in fuel consumption.
Last edited by tubby linton; 16th Jan 2015 at 20:25.