Originally Posted by
mickjoebill
Is there a reason why the supply tanks aren't designed to be physically lower than the main tank and so could be fed by gravity in the event of pump failures? Mickjoebill
The answer to that is probably resident somewhere in Eurocopter/Airbus Helicopters, or among the old hands from Messerschmitt-Bölkow-Blohm
(if anywhere). If you look at the original spec/requirements documents for the various versions of this model's predecessor(Bo105, etc) I suspect the answer will lie there. The weight and cost of two internal transfer pumps added where purely gravity feed would require ... zero
suggests to me that a particular requirement was being met.
I'll hazard a guess: an issue in design that some call a "graceful degradation" feature. If one tank has a leak, you don't necessarily lose all of your fuel ... but that's a general not a specific answer.
I'd need to go back a few dozen pages, or maybe in the EC-135 thread, but there was quite a bit of discussion on that point in the weeks after the crash.