A320N1

[Flyman35]

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?.

[Fargoo]

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.

[learner001]

A320 IAE Engine: 34%

Kind regards, learner . . .

[Neupielot]

A320 IAE Engine: 34%

Same.

[PappyJ]

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.

[TyroPicard]

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

[EMIT]

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.

[FlightDetent]

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

- THR LEVER (affected) .................................. IDLE
- ENG MASTER (affected) .................................OFF

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)

[Flyman35]

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