A320 fuel penalty

[TTT0521]

Hey guys

I have a question about fuel penalty of Aileron.

In the case of ELAC 1 or 2 or 1＋2 fault, ECAM says that we need to apply fuel penalty factor table.
And explanation is FUEL CONSUMPT INCRSD appears when the failure (or combination of failures) affects the nominal aerodynamic characteristics of the aircraft.

But FCOM says that if Aileron fails, then damping mode will active.
Damping mode doesn’t make any fuel penalty. Is that right?
And if it is correct, the penalty factor table is used only in the case of damping mode doesn’t work correctly.

Then if airbus consider that case, why there are no fuel penalty table for Elevator?
I feel little bit contradiction and I thought I misunderstanding something.

Thanks

[vilas]

Originally Posted by TTT0521

Hey guys

I have a question about fuel penalty of Aileron.

In the case of ELAC 1 or 2 or 1＋2 fault, ECAM says that we need to apply fuel penalty factor table.
And explanation is FUEL CONSUMPT INCRSD appears when the failure (or combination of failures) affects the nominal aerodynamic characteristics of the aircraft.

But FCOM says that if Aileron fails, then damping mode will active.
Damping mode doesn’t make any fuel penalty. Is that right?
And if it is correct, the penalty factor table is used only in the case of damping mode doesn’t work correctly.

Then if airbus consider that case, why there are no fuel penalty table for Elevator?
I feel little bit contradiction and I thought I misunderstanding something.

Thanks

Elevators move together. In case of dual hydraulic failures one side may be frozen. The fuel penalty factor for dual hydraulic failure includes one side elevator jam.

[request]

Hello everyone,

I would like to know if you can give me an example of how to calculate the Fuel Penalty Factor in the A320 with a landing gear failure that is 180%. I know how to calculate the Trip fuel penalty, but I don't know where to apply or add that result to know what my real fuel would be at landing.

Would an example with numbers be possible?

Thank you

[iggy]

FOB = 9 tons
EFOB at destination in FMGC = 3 tons

Therefore, trip fuel is 6 tons, 6 x 1.8 = 10.8 tons actual trip fuel with landing gear failure.

I honestly hope it goes like this because this is how I have been explaining it to my trainees for years now...

[request]

Thanks for the reply.

And when would you declare Minimum fuel, that is, knowing your new trip fuel, how do you calculate the minimum diversion, which is the sum of the final reserve and alternative?

[KingAir1978]

Originally Posted by iggy

FOB = 9 tons
EFOB at destination in FMGC = 3 tons

Therefore, trip fuel is 6 tons, 6 x 1.8 = 10.8 tons actual trip fuel with landing gear failure.

I honestly hope it goes like this because this is how I have been explaining it to my trainees for years now...

This calculation is not correct, I'm afraid. The PENALTY is 180%. Therefore the total fuel used would be the fuel normally used PLUS the penalty. You have only calculated the penalty (6x1.8 = 10.8) The total fuel burn would thus be the 6 tonnes, PLUS the 10.8. = 16.8 tonnes. Also you may need to include the penalty for open gear doors of 15%. To be conservative just multiply the fuel-burn by 3.

[request]

Originally Posted by KingAir1978

This calculation is not correct, I'm afraid. The PENALTY is 180%. Therefore the total fuel used would be the fuel normally used PLUS the penalty. You have only calculated the penalty (6x1.8 = 10.8) The total fuel burn would thus be the 6 tonnes, PLUS the 10.8. = 16.8 tonnes. Also you may need to include the penalty for open gear doors of 15%. To be conservative just multiply the fuel-burn by 3.

Thanks! What would be the new EFOB at destination with this failure?

[thetimesreader84]

Without wanting to drift too much, I've been given a rule of thumb that with gear stuck down, the first 2 digits of your FOB is how many minutes until tank's are dry.

eg FOB 2800kg = 28 minutes until tank's are dry.

Hopefully never have to find out if its true!

[vilas]

Originally Posted by thetimesreader84

Without wanting to drift too much, I've been given a rule of thumb that with gear stuck down, the first 2 digits of your FOB is how many minutes until tank's are dry.

eg FOB 2800kg = 28 minutes until tank's are dry.

Hopefully never have to find out if its true!

Gear stuck down is serious situation can you depend on a thumb rule? Why not just open QRH have accurate analysis? Qantas 747 400 at Hongkong asked to hold at higher than normal altitude used a thumb rule for holding speed instead of FMS speed and stalled the aircraft thrice in the hold.

[dixi188]

Try this for an example of what can go wrong.
Hapag Lloyd A310 at Vienna July 12 2000.

[iggy]

Originally Posted by KingAir1978

This calculation is not correct, I'm afraid. The PENALTY is 180%. Therefore the total fuel used would be the fuel normally used PLUS the penalty. You have only calculated the penalty (6x1.8 = 10.8) The total fuel burn would thus be the 6 tonnes, PLUS the 10.8. = 16.8 tonnes. Also you may need to include the penalty for open gear doors of 15%. To be conservative just multiply the fuel-burn by 3.

It's scary to think how many pilots must be calculating it the wrong way after I taught them, right?

[k.swiss]

Originally Posted by iggy

FOB = 9 tons
EFOB at destination in FMGC = 3 tons

Therefore, trip fuel is 6 tons, 6 x 1.8 = 10.8 tons actual trip fuel with landing gear failure.

I honestly hope it goes like this because this is how I have been explaining it to my trainees for years now...

Interesting..

Originally Posted by KingAir1978

This calculation is not correct, I'm afraid. The PENALTY is 180%. Therefore the total fuel used would be the fuel normally used PLUS the penalty. You have only calculated the penalty (6x1.8 = 10.8) The total fuel burn would thus be the 6 tonnes, PLUS the 10.8. = 16.8 tonnes. Also you may need to include the penalty for open gear doors of 15%. To be conservative just multiply the fuel-burn by 3.

Very interesting..

So which one is it? May someone explain with another example perhaps?

[request]

Originally Posted by k.swiss

Interesting..

Very interesting..

So which one is it? May someone explain with another example perhaps?

Hi, could you give me a better example, please?

[FlightDetent]

[penalty +30%] >>> FMS burn (100%) + 30% = 130% = 1.3 x FMS
[penalty +180%] >>> FMS burn (100%) + 180% = 280% = 2.8 x FMS

Don't forget the additional +15% for doors ajar in case of gravity extension.

[vilas]

Since penalty factor of 180% is huge so the calculation is creating some confusion. Let's take FOB 6000kgs and EFOB 4000kgs. That gives burnoff of 2000kgs. Take a penalty factor of say 15%. When applied to 2000kgs will give 300kgs. Surely that can't be the BO with failure but only additional fuel required. It will be added to normal burnoff of 2000kgs giving the figure off 2300kgs as the trip fuel with failure. So the new EFOB with FPF will be
6000-2300=3700kgs.This should make it clear.

[tubby linton]

Looking at an old Safety First magazine Kingair1978 is correct.

[k.swiss]

Originally Posted by vilas

Since penalty factor of 180% is huge so the calculation is creating some confusion. Let's take FOB 6000kgs and EFOB 4000kgs. That gives burnoff of 2000kgs. Take a penalty factor of say 15%. When applied to 2000kgs will give 300kgs. Surely that can't be the BO with failure but only additional fuel required. It will be added to normal burnoff of 2000kgs giving the figure off 2300kgs as the trip fuel with failure. So the new EFOB with FPF will be
6000-2300=3700kgs.This should make it clear.

Thanks vilas
First question, is the penalty not also applied to alternate/final reserve fuel incase of GA?
Second, to summarize if at any point the EFOB (with penalty) goes below the actual EFOB on the MCDU then we can not continue and better to divert as fuel will not be enough given the penalty?

Originally Posted by FlightDetent

[penalty +30%] >>> FMS burn (100%) + 30% = 130% = 1.3 x FMS
[penalty +180%] >>> FMS burn (100%) + 180% = 280% = 2.8 x FMS

Don't forget the additional +15% for doors ajar in case of gravity extension.

Thanks FlightDetent

[iggy]

Originally Posted by KingAir1978

This calculation is not correct, I'm afraid. The PENALTY is 180%. Therefore the total fuel used would be the fuel normally used PLUS the penalty. You have only calculated the penalty (6x1.8 = 10.8) The total fuel burn would thus be the 6 tonnes, PLUS the 10.8. = 16.8 tonnes. Also you may need to include the penalty for open gear doors of 15%. To be conservative just multiply the fuel-burn by 3.

You were totally right, the answer can be found in this Airbus Safety Magazine from 2012: https://www.ukfsc.co.uk/files/Safety...Jan%202012.pdf

The two key points to look for this question are:

How to calculate Additional Fuel

Additional fuel must be added to the fuel prediction calculated by the FMS.

I repeat: it is scary to think the amount of pilots that are going to run out of fuel in the air after I taught them the wrong way.

And, totally unrelated to this thread, but worth mentioning: I got the answer to this from the nerdy, sweet, glasses-wearing, non-aviation related, amazingly intelligent, humorous, incredibly hot and with magic eyes, love of my life. It took her less than 5 minutes to come with a well documented answer, even though the closest she has been to an airplane has been as a passenger. And on top of that, her nickname is an acronym that we pilots use on a daily basis, can't ask for more!

So, this is to you, I know you are going to love it. Happy belated Saint Valentine!

[FlightDetent]

Originally Posted by iggy

I repeat: it is scary to think the amount of pilots that are going to run out of fuel in the air after I taught them the wrong way.

Perhaps I am missing the sarcasm.

You did not teach them to use 15% instead of 115% for the smaller failures (a.k.a. 85 less fuel).

Forgetting about the baseline 100 in the l/g down case is a widespread error, but a well identified one. Re-assimilation in progress for many years.

If you missed the moment to point this visual trap, it's a lost opportunity, no worse. Sure as hell the 180+15 look bad enough already.

[iggy]

Originally Posted by FlightDetent

Perhaps I am missing the sarcasm.

You did not teach them to use 15% instead of 115% for the smaller failures (a.k.a. 85 less fuel).

Forgetting about the baseline 100 in the l/g down case is a widespread error, but a well identified one. Re-assimilation in progress for many years.

If you missed the moment to point this visual trap, it's a lost opportunity, no worse. Sure as hell the 180+15 look bad enough already.

I mean that I taught them to calculate it this way FOB-EFOB (9-3 tons in my example), multiplied by whatever factor they see in the FPF chart. Obviously, if it is a mere 10% I would be adding it to the trip fuel without a malfunction (6 + 0.6 (10% of 6) = 6.6 actual trip fuel), but in the specific case of landing gear legs down (180%), I'm afraid I didn't, and they would be thinking that the trip fuel with in that case would be 10.8 instead of 16.8 tons. About the 15% extra, I guess I included it in my explanations, but... what is the use of including it if the method of calculating it is wrong?