2 expanded, clarified
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To my understanding, the input from the MAN START p/bswitch (a ground/open discrete into the Engine Interface Unit), is only taken into account by the FADEC logic if the engine is not already running (engine running = N2 above idle). Once the engine control logic goes into running mode, the only way to come out of it (from the FADEC's point of viewi.e. N2 rises above idle) is to set, it will stay in that mode until the engine master lever (EML) is set to Off, so it would appear that even in caseregardless of flame-outwhether the engine is lit or not.

In other words, once the engine has started, the position of the MAN START p/b is irrelevant, even if the engine flames out (however, note that the FCOM procedures for engine failure often call for the EML to be set to Off, at which point the position of the MAN START switch comes to play in any subsequent attempt to relight the engine).

One risk I can think of is that if you are on the ground, shut the engineengines down, or even power off the aircraft, then when you power everything back on and attempt to start thean engine (i.e. turn the engine start selector to IGN), the autostart procedure will be inhibited by the MAN START p/bswitch being already on, and the FADEC will go into manual start mode instead. Engine relight in flight could also If you then immediately set the EML to On (which wouldn't be affected, I supposea problem during a normal autostart), but Ifuel would havestart to look at it more in detailflow right away, while the engine may still be below the required minimum N2 for fuel admission (16%), therefore the engine could fail to start or worse (an engine fire).

To my understanding, the input from the MAN START p/b (a ground/open discrete into the Engine Interface Unit), is only taken into account by the FADEC logic if the engine is not already running (engine running = N2 above idle). Once the engine goes into running mode, the only way to come out of it (from the FADEC's point of view) is to set the engine master lever (EML) to Off, so it would appear that even in case of flame-out, the position of the MAN START p/b is irrelevant (however, note that the FCOM procedures for engine failure often call for the EML to be set to Off).

One risk I can think of is that if you are on the ground, shut the engine down, or even power off the aircraft, then when you power everything back on and attempt to start the engine (i.e. turn the engine start selector to IGN), the autostart procedure will be inhibited by the MAN START p/b being already on, and the FADEC will go into manual start mode instead. Engine relight in flight could also be affected, I suppose, but I would have to look at it more in detail.

To my understanding, the input from the MAN START switch (a ground/open discrete into the Engine Interface Unit), is only taken into account by the FADEC logic if the engine is not already running. Once the engine control logic goes into running mode (i.e. N2 rises above idle), it will stay in that mode until the engine master lever (EML) is set to Off, regardless of whether the engine is lit or not.

In other words, once the engine has started, the position of the MAN START p/b is irrelevant, even if the engine flames out (however, note that the FCOM procedures for engine failure often call for the EML to be set to Off, at which point the position of the MAN START switch comes to play in any subsequent attempt to relight the engine).

One risk I can think of is that if you are on the ground, shut the engines down, or even power off the aircraft, then when you power everything back on and attempt to start an engine (i.e. turn the engine start selector to IGN), the autostart procedure will be inhibited by the MAN START switch being already on, and the FADEC will go into manual start mode instead. If you then immediately set the EML to On (which wouldn't be a problem during a normal autostart), fuel would start to flow right away, while the engine may still be below the required minimum N2 for fuel admission (16%), therefore the engine could fail to start or worse (an engine fire).

1
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To my understanding, the input from the MAN START p/b (a ground/open discrete into the Engine Interface Unit), is only taken into account by the FADEC logic if the engine is not already running (engine running = N2 above idle). Once the engine goes into running mode, the only way to come out of it (from the FADEC's point of view) is to set the engine master lever (EML) to Off, so it would appear that even in case of flame-out, the position of the MAN START p/b is irrelevant (however, note that the FCOM procedures for engine failure often call for the EML to be set to Off).

One risk I can think of is that if you are on the ground, shut the engine down, or even power off the aircraft, then when you power everything back on and attempt to start the engine (i.e. turn the engine start selector to IGN), the autostart procedure will be inhibited by the MAN START p/b being already on, and the FADEC will go into manual start mode instead. Engine relight in flight could also be affected, I suppose, but I would have to look at it more in detail.