Communicating
Interesting:
One question, five answers.
Two answers, i.e. 40%, do not answer the question, the respondents have not properly understood what was being asked.
Aviation is very much a communication business, be it between pilots and air traffic control, or between aircraft builders and users (through FCOM, FCTM, etcetera).
Let me explain the question, I will use figures for PW-4060 engines, the A-320 engines have faded too much from my memory.
Start parameters (seen in a negative way, that means, abort engine start when any of these parameters occurs)
* No rotation (N2)
* No oil pressure (when reaching the normal FUEL RUN N2)
* No lightup in 20 seconds
* No N1 before reaching 45% N2 (this is the figure that Flyman35 was looking for)
* Unusually high fuel flow
* EGT rising abnormally rapid through 425, or going over limit of 535
* Engine stable not reached within 120 seconds after FUEL RUN
(last condition to be tempered by common sense, e.g. if you start using a weak external air starter and have a max. motoring N2 only just above the minimum approved value, the initial firing up could take a lot of time, with higher EGT's than usual, but as long as everything is nicely controlled by the EEC, let it go)
So sorry flyman, I can't provide the figure you were looking for, but couldn't resist to highlight yet again the pitfalls in communication that so often occur in aviation. I hope that this reply will help others to give you the sought after answer.