A320 IAE Engine start up
 

Hi,
I was in the sim yesterday and noticed the following. Upon starting engine 2 the N1 display on the upper ECAM does not appear until N2 reaches about 25%. The N1 display is amber and the digital indication contains crosses until 25% N2. The EPR and N2 are available. Does anyone know if this is normal ?? Any help would be appreciated.
Regards,
CL

Yup!

Perfectly normal! :ok:

On all IAE starts I've seen, the N2 is also amber crossed until about 5% N2 when it suddenly comes alive. As you say, the N1 comes alive mouch later on.

This would apply to both engine starts. Not just the No.2.

I have my sim in a couple of days, so i will look out for it. I assume you mean just in the sim? Starting up in the plane, the N1 indication doesn't appear until actual N1 is about 3.5% (according to FCOM). The N1 indication isn't reliant upon the N2 indication as such except that N1 won't reach high enough levels until N2 is around the 25% mark, so the indications remain amber crosses. I hope this is what you were looking for, if not, I will do my best to clarify.

5% N2 is when the dedicated generator comes on line ..:)

why don't you just git a pair of good old CFM 56 5B's ... and before you can sneez you can ask for Taxi :ok:

Hi,
Thanks for the reply guys. If this occurs in the sim then it should be replicated in the real aircraft. The sim is certified level D. I had a brief look in my FCOM under chapter 70 (powerplant). I could not find anything that states N1 displays amber crosses until N2 is about 25%. Am I looking in the right section? The engine type is V2527-A5. Is there any other documentation that states this?
Cheers,
CL.

This is absolutely normal for V25 series engines. Apparently, the N1 sensor does not generate a reliable output unitl about 5% (which occurs at about 25% N2). So, you will see this effect on every start-up (A/C and sim).

On the CFM engine you get the N1 displayed but its often a bit wobbly until it get over about 5%.

Hope that helps