A320N1
 

Hi
A32-_CFM Engines.
Some one asked what is the N2 parameter at starting the engine where you suspect if the N1 is not rotating by N2 reaching a certain parameter?what is that N2 parameter?:confused:.

If you do a manual start you set the master switch to on a 20% N2, not heard of a magical figure though as the guy outside should be confirming positive rotation.

A320 IAE Engine: 34%

Kind regards, learner . . . ;)

Same. :ok:

IAE and CFM engines are different when doing manual starts. This is due to the 30 seconds of dry cranking required by the IAC engine. Consequently, fuel goes on a different speeds. I recall it's around 20% for CFM and around 35 for IAC. The CFM is purely based on N1, where the IAE is both N1 and a 30 second rotation time. Of course, it's been a while but that's how I recall it.

CFM - no magic number in FCOM, but ECAM will give you a LOW N1 caution for no rotation.

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.

TP is correct, no such number in FCOM. An ECAM warning is described under Abnormals in book 3:

ENG 1(2) LOW N1 (on ground)
No N1 rotation during start

• IF CONFIRMED

Usually more information on trigger values is found in book 1 under Warning & Cautions for the given system. In this case however, the only description is "No N1 rotation during start".

Sincerely,
FD (the un-real)

thanks for the answers I thought there was a certain value some where,but it's clear now.:D