Originally Posted by
OK465
I would have phrased that differently (i.e. 'still alive').
Each JT8 engine had two ignitors, one capable of being battery powered for a ground battery start when the APU was on the 'fritz' (and no external electrical available). (assuming you had external air)
Kept an engine running at San Angelo, Texas once for this very reason (i.e. no external air or electrical available and a questionable APU).
Thanks, found it under Battery Start Checklist. No APU generator and no GPU available is when you do it as said. I think I used to know that.
It appears either igniter can be selected but only one at a time based on selector position. I suppose only the engine being started gets ignition as it is based on fuel lever position.