Takeoff with reduced power

[Maximilian94]

Hello guys

Good morning / Good afternoon / Good evening

I'm studying about “Takeoff with reduced power”, i read several things on the internet, but I still have some doubts.

I will explain what I've learned so far:

The higher the temperature, lower the power. That is, as the temperature increases, minor will be the maximum weight for Takeoff.

So let us suppose that the outside temperature is 20 degrees, is with this temperature the plane can take off with 70 tons, but the aircraft is 65 tons.

Now assume that at 40 degrees, the limit is 65 tons to take off, then, we will put in FMGS system, the temperature of 40 degrees. This means that we are talking to the FADEC, “I want to take off with TOGA at 40 degrees”.

Now comes my question,

How the FADEC knows the maximum power that he can make at 40 degrees?
It has a database?

What the FADEC do when we put the levers in TOGA?

How the FADEC does knows the power that need to put, if we don’t put neither temperature?

What happens if we put a flex temperature lower than the outside temperature?

It has to do with EGT limit?

If possible, I would like to know any link that I can study about this.


I apologize to grammar errors, I am still learning English

Thanks for attention

Maximilian Kaden

[Goldenrivett]

Hi Maximilian94,
Try reading this document especially from Page 87 onwards.
http://www.skybrary.aero/bookshelf/books/2263.pdf

[Piltdown Man]

How the FADEC knows the maximum power that he can make at 40 degrees?It has a database?

Yes or a method of calculating the power that will be produced at a given temperature and barometric setting.

What the FADEC do when we put the levers in TOGA?

It sets the power according to the temperature you have entered.

How the FADEC does knows the power that need to put, if we don’t put neither temperature?

You have to enter a temperature.

What happens if we put a flex temperature lower than the outside temperature?

That is impossible because you are now demanding more thrust than the engines can provide. If you need that performance you are overweight. Therefore you change the aircraft's configuration, the runway you are using or reduce the payload.

It has to do with EGT limit?

You use reduced thrust to reduce the engine's operating temperature and resulting wear and tear on the engine and airframe. You are unlikely to be near the operating limit of the engine.

PM

[Cough]

What the FADEC do when we put the levers in TOGA?

It sets the power according to the temperature you have entered.
(A320 series). It sets full power. Every time. If you set the levers in the FLX/MCT gate, it will set the power to the reduced thrust level.

How the FADEC does knows the power that need to put, if we don’t put neither temperature?

You have to enter a temperature.
If you don't enter a temperature and set the levers to FLX/MCT, a warning is generated to set the levers to full thrust position (TOGA). The aircraft has sensors for the OAT, you don't have to enter it.

ps. Flex lower than the OAT, the FMGC gives an 'invalid entry' type warning and doesn't accept the entry. i.e. you can't do it.