You’re on the right track
G’day Mooneyboy,
With gear down, you are almost tripling (x3) your fuel burn, there is lots of drag with the LG and the doors hanging out.
So you do the Fuel penalty, then add it to the planned burn, or as the QRH says,
TRIP FUEL PENALTY = (FOB - EFOB at DEST) x FPF
So, if we just do the numbers for holding, from your figure :
Clean @ 60t @FL100 = 2118kg/h +
Fuel penalty factor (2118*180%) = 3812kg/h
Total fuel req’d to hold for 1 hour = 5930kg
I’m guessing you got some holding Config 1 figures somewhere, my manuals don’t have them, but my guess is Config 1 gives a better fuel flow because of Slats out.
Holding with Slats is ok, but it is pretty slow, and not a great idea in If ICE might be present, but you need to avoid ICE with the gear down too. Also, with all that drag from the gear, Green dot +20kts will be much more comfortable while you sort out the issues.
This abnormal kind of makes things a bit time critical, and with this in mind, better to keep things as simple as possible. Of course, if you have to go to a take off alternate, those sort of fuel flows might be a big problem.
I hope that helps.
If your lucky, Villas will see this, he seems to be pretty clever about all things Airbus, so maybe we can all learn some more.