A330 - Reduction of G/A weights in N1 mode

[Mo Heekan]

Hi all knowing techies,

I'm pondering and need help please; under N1 thrust control, our in flt perf book says that there is a reductive weight penalty to be applied if in N1 mode. These weights range from 28-45 Tons depending on normal g/a weight.

I'm stuck on;

a. These weight decrements seem massive. Does anyone know why they are so huge?
b. If they are to be applied to 1 engine ops (not your day), what do you do to your single engine g/a weight that you've calculated (i.e. with the 2.5 % g/a requirement we have on 1 engine)?
c. If I read it correct, as an example; there is a 32 Ton penalty if landing around your normal configuration weight. This would mean you need to run out of fuel before you could be down to the weight to g/a. It doesn't sound right.

What am i doing wrong? I'd appreciate any feedback please

Thanks

[shimmydamper]

Hello,

the weight resctriction is because in unrated mode there is no protection in the engine, you have to find the goaround powersetting in the Fcoms, and set them yourself(no Toga)
these ga settingstables are based on single eng. so the weight you will find in the table is for single eng. and should give you 2.5% so on 2 eng you will have a better gradient.

The weight correction according the Unrated mode table is NOT for your actual weight that you have, but is based on the actual
weight you have to get out of the table.(WAT)
which can be more than actual mtow.
so if that weight(table)is 237 and your correction 32, weight for Ga can be 205tons, and that should be no problem. fuel wise.

The Fcoms are not very clear on this subject.

this is the way I read it, and maybe there are other people with different views in ths subject.

S.

[Mo Heekan]

Shimmy, you're a bally star!

You've allowed me to sleep at night, and I thank you :)

Kind regards

Mo