View Full Version : Airbus QRH Fuel penalty
olirindis
23rd Jun 2017, 04:34
Greetings all,
The A320 QRH Fuel penalty tables refer.....
If I'm diverting to a takeoff alternate with the gear fully extended because of an unlock fault after takeoff, the table in the QRH lists a penalty factor of 180%.
What figure is this factor applied to?
Thanks in anticipation!
EGPFlyer
23rd Jun 2017, 05:03
Your normal fuel burn for the flight to the alternate. If it was 1500kg, your new burn would be 1500kg +fuel penalty factor (180% of 1500kg) which is 3700kg
1500 x 180% = 2700 + 1500 = 4200
EGPFlyer
23rd Jun 2017, 05:22
Cheers, thats what happens when I try to do maths at 6am without coffee :ok:
EGPFlyer
23rd Jun 2017, 05:39
Yeah, you are calculating the fuel penalty factor which has to be added to your normal burn. They used to just say multiply normal burn by 2.8 (for gear down) but it changed a few years ago... no idea why.
Capt Groper
1st Jul 2017, 18:47
I believe that the FPF needs to be applied to Remaing Trip (at current alt and GS) + Contingency + Final Reserve Fuel.
For example if landing gear locked down (FPF 2.0) and FMS says at Fl 200 and GS of 240kt with FL200 winds inserted in FMS the trip is 15T Contingency 2T and FR 3.0T
Then 15+2+3=20t x 2 = 40T if you have 40T then you could continue. If not then return or divert to a much closed airport.
Peter G-W
1st Jul 2017, 22:29
You shouldn't really land at a closed airport.
With landing gear down you wouldn't go far. Contingency is for despatch for unforeseen winds, level etc. Once airborne it is not increased with failures.
applecrumble
8th Jul 2017, 06:49
What about alternate fuel?
If you have just departed and then run the calculation I would still apply the factor to my required alternate fuel.
I know you can obviously commit to your destination but I wouldn't do that at the start of a flight.
Best thing to do in midflight is go to DATA----CLST APT---EFOB/WIND and you get four closest airports(fifth can be added) with EFOB without failure, minus that from FOB, you get burn off to the desired alternate without failure. Apply the FPF and you get burn off with the failure. Minus it from GW to get Landing WT at alternate.
CallmeJB
9th Jul 2017, 04:18
You lost me when you verbed minus.
DATA---CLOSEST APT---EFOB/WIND.Take EFOB for chosen APT. Now present FOB-EFOB= Burn off (normal) This BO+ FP = BO with failure(penalty). Now Present GW - (corrected)BO= LW at alternate.Calculate LD for this LW.
Gauges and Dials
11th Jul 2017, 03:27
Yeah the 2.8 factor is much clearer. It appears then that the extra burn gear down is far more significant than in our old dirty turbo prop ;)
A modern jet transport in clean configuration is slippery indeed. When I take a step back, stop taking modern tech for granted for a second, and look at the sheer mass being pushed through the air and consider the (relatively tiny by historical standards) fuel burn, I find the numbers nothing short of incredible. I imagine even sticking a pencil out the window would make a measurable difference ;-)
olirindis
24th Jul 2017, 05:31
If only one Fuel Penalty Factor (FPF) is applicable:
TRIP FUEL PENALTY = (FOB - EFOB at DEST) x FPF
The FMS fuel predictions must be recomputed to take into account this trip fuel penalty.
This last sentence is a trifle confusing/misleading, the paragraph is an extract from an A320 QRH. Does it mean that the FMS must be reprogrammed to reflect both the chosen diversion airfield as well as the greatly reduced CLB/CRZ/DES speeds and possibly lower CRZ FL? And once done, the revised EFOB is applied to the formula? Or is it the original "clean aircraft" trip fuel profile that is used?