What's the smell when starting an APU?

Posted by Deltahal@reddit | aviation | View on Reddit | 19 comments

Idk if this is the right place to ask but when starting up a plane, there's a sweet kid of slightly fruity??? smell??? after the APU starts up until the first engine starts spinning. I can't for the life of me figure it out, since shouldnt it basically be just carbon di(?)oxide and stuff coming out??