IAE V2500 FADEC Start
Thread Starter
Join Date: Sep 2002
Location: Hong Kong
Posts: 11
Likes: 0
Received 0 Likes
on
0 Posts
IAE V2500 FADEC Start
Hello Gentlemen,
This is my first post on this particular forum so I ask for your patience. On the A320 with the V2500 engines and presumably also the CFMs, the grey background on the N2 disappears when the engine has rolled back and stabilised at idle. Having checked and trained on the aircraft for many years, I have always gone and espoused the line that the grey background disappears when FADEC is satisfied that the engine has started properly and (I assume) has gone out of what I would call a 'start mode' into a normal engine monitoring mode. To add to the confusion, the grey background is also there on a manual start and the FCOM makes it clear that start protections are not available. Unfortunately, I cannot find any reference to support this in the FCOM and I don't want to be telling people information that is incorrect so can anyone tell me when the grey background is supposed to disappear and also what it signifies? References would be useful. I am sure this has come up before and I apologise for flogging a dead horse but I would like to be able to put this one to bed.
This is my first post on this particular forum so I ask for your patience. On the A320 with the V2500 engines and presumably also the CFMs, the grey background on the N2 disappears when the engine has rolled back and stabilised at idle. Having checked and trained on the aircraft for many years, I have always gone and espoused the line that the grey background disappears when FADEC is satisfied that the engine has started properly and (I assume) has gone out of what I would call a 'start mode' into a normal engine monitoring mode. To add to the confusion, the grey background is also there on a manual start and the FCOM makes it clear that start protections are not available. Unfortunately, I cannot find any reference to support this in the FCOM and I don't want to be telling people information that is incorrect so can anyone tell me when the grey background is supposed to disappear and also what it signifies? References would be useful. I am sure this has come up before and I apologise for flogging a dead horse but I would like to be able to put this one to bed.
Join Date: Jan 2006
Location: I dont know anymore
Posts: 37
Likes: 0
Received 0 Likes
on
0 Posts
You are correct that in a manual start the FADEC does not auto-abort.
However it still passively monitors the engine.
The grey background will disappear once the engine is stabilised with : Ingition off, Start valve crossline, idle parameters normal.
Even in the manual start sequence, the FADEC still controls the above (ignition, start valve).
Ref: FCOM 1.70.20 P3, FCOM 3.04.70 P5
However it still passively monitors the engine.
The grey background will disappear once the engine is stabilised with : Ingition off, Start valve crossline, idle parameters normal.
Even in the manual start sequence, the FADEC still controls the above (ignition, start valve).
Ref: FCOM 1.70.20 P3, FCOM 3.04.70 P5
1. No idea. My FCOM 1.70.20 p3 (V2500) lists the FADEC functions, but doesn't go into that much detail.
2. FCOM 3.03.08 p2 states eng 1 should be started after the grey background disappears.
2. FCOM 3.03.08 p2 states eng 1 should be started after the grey background disappears.
Join Date: Feb 2005
Location: flyover country USA
Age: 82
Posts: 4,579
Likes: 0
Received 0 Likes
on
0 Posts
From a purely pneumatic standpoint, the second start should be possible as soon as the first starter has cut out. However, that could make for an interesting fire drill. 
Join Date: Mar 2000
Posts: 17
Likes: 0
Received 0 Likes
on
0 Posts
I agree that from a pneumatic point of view, you could technically start the second one as long as the valve on the other side is closed.
If you do so, what would happen if the FADEC would detect a start fault on the first engine that was started ? I guess it wouldn't be able to dry crank if required. Would both pneumatic valve be opened at the same time ?
If you do so, what would happen if the FADEC would detect a start fault on the first engine that was started ? I guess it wouldn't be able to dry crank if required. Would both pneumatic valve be opened at the same time ?
Guys I fly with who used to fly with Ansett say they started the second when the start valve went crossline. One pilot started one, the other the second so that the first could continue to monitor his start.
Ansett did have some wacky ways of doing thing though. Thinking of FEs on 767s!
Ansett did have some wacky ways of doing thing though. Thinking of FEs on 767s!
The Bumblebee
Join Date: Jul 1999
Location: Inside the shiny tube.
Posts: 333
Likes: 0
Received 0 Likes
on
0 Posts
I am not too sure about the CFM engines but in our IAE engines FADEC is monitoring till 50% and after that it is passively monitoring the engines. You can find the information in 1.70.80 page 4. Of course it does not explains why FADEC monitors it only till 50% N2 and leaves it on to us human beings after that!!!!
Also it is not written anywhere but a very wise MEA captain once told me to start the second engine only after the first one (#2 in our case) has reached peak EGT and there is a drop in the EGT. This way at least you are sure that you will not need bleed source in case of engine tail pipe fire or hot start.
Also it is not written anywhere but a very wise MEA captain once told me to start the second engine only after the first one (#2 in our case) has reached peak EGT and there is a drop in the EGT. This way at least you are sure that you will not need bleed source in case of engine tail pipe fire or hot start.
Join Date: Feb 2005
Location: flyover country USA
Age: 82
Posts: 4,579
Likes: 0
Received 0 Likes
on
0 Posts
Also it is not written anywhere but a very wise MEA captain once told me to start the second engine only after the first one (#2 in our case) has reached peak EGT and there is a drop in the EGT. This way at least you are sure that you will not need bleed source in case of engine tail pipe fire or hot start.
