Originally Posted by
siropalomar
Ok, I’ve read it, but doesn’t help much. The question is: do A320’s lose FDR after a loss of thrust on both engines? It’s clear RAT will deploy, it’s clear RAT will power an emergency generator (as it will power a hydraulic system which will power that generator), and I believe FDR readouts are essential for investigators, before and after the thrust loss. It’s clear, though, that FDR is not essential for flying the plane safely after the thrust loss....
What he was saying is that keeping the FDR powered is easy. That's not a problem. However the FDR gets a number of inputs from tons of sources. In order for those sources to provide
usable data to the FDR, they must be powered. In an emergency electrical situation, it's impractical/impossible to power all the necessary data sources. Hence, the designers don't waste valuable electrical energy powering a recorder that's just getting garbage data.