Airbus FBW family - Engine N1

[AirbusFan]

Please could you assist with an armchair avaiators understanding of N1 presentation and turbine engines in general.

1) I understand that the N1 limit is shown in the ECAM by an amber mark. Does the value of the limit change with pressure and temperature or is it a fixed value?

2) When TOGA is selected (or under any other condition) is it possible to exceed the N1 value or is it limited by the FADEC to the maximum permissible for the conditions?

3) What N1 value is MCT in relation to TOGA?

4) Does the amber N1 limit change change if a FLEX value is used or is it always the same i.e the maximum permissible for the conditions?

5) If no FLEX value is loaded is MCT the value that is available in the FLEX/MCT thrust lever position?


Thanks in advance

AirbusFan

[Carnage Matey!]

Aaaah, technical stuff huh? Well off the top of my head I think the answers are as follows:

1) N1 amber mark is fixed, its the maximum rotation rate of the big fan.

2) I think FADEC prevents you exceeding N1 max to stop the engine disintegrating.

3) That would depend on ambient pressure and temperature. Don't know an easy answer.

4) Amber N1 is fixed - its the maximum limit.

5) Pass, but you will get an ECAM warning if you select FLX for take off without a Flex temp set.

Caution: I don't fly CFM engines very often so I could be wrong about N1 stuff, and I have been drowning my sorrows after the football so this could all be garbage.

[lomapaseo]

Please could you assist with an armchair avaiators understanding of N1 presentation and turbine engines in general.


No easy explanation of whys and wherefors...just the SOPs etc.

Mostly the limit is to protect the mechanical integrity of a functioning engine, i'e. one where the other parameters, temperature and pressure are somewhat withn limit ranges ( 10% overages on the other parameters will have negligible effect on N1 limit)

The N1 limit protects the turbine rotors from stretching to the point of serious damage as well as protects all rotors from getting themselves into catastrophic vibration modes.

Note: the above is a generality and your mileage may vary