I don't know why I made this 'dumb' mistake (in fact never done it before - been flying for years and I always check) - but I hadn't fully secured one of the propellors.

So tried to take off from a cement ground, and one of the props went flying off - I think the phantom maybe only got a foot off the ground, then obviously landed and turned off.

Looking now - it looks like there are some very tiny hairline fractures on the underside of both motors.

Is it dangerous to fly now, or is it safe/can I still fly it?

Even though I am out of the warranty period - I would actually send it into the techsupport to get it replaced if it wasn't for the fact that they upgrade the firmware and force new flight restrictions on you (i.e., I think the 'no fly' areas database they install on your machine is now probably 10x the size from when I got it). And who knows what else they do.

Maybe I am being super overcautious, I don't know - but I just want to make sure it is safe to fly. If anyone can give me insight, that would be great. They really are 'hairline' fractures (like you really have to look to see them, but I can see them) - so highting them in red as well.

This is a picture of the underside:

You can replace the "shell" case for the drone by purchasing it in the DJI store.
A stress fracture like that can only get worse, even in simple elements whereby heat and cold might cause the material to "expand" and "contrast" or simple vibration.  It might work for a while but it could be a ticking time bomb as well.

I see. How easy is it to replace that? Seems a bit complicated to me... Any youtube videos?

I would recommend you to start a repair case and send it in for diagnosis and repair: http://www.dji.com/support. Chargeable service will be applied as it has been out of warranty, please kindly note.

@ Susan. Is there someway I can make sure you guys DO NOT update my firmware? If you can replace the case *without* updating my firmware, I would definitely do that.

I do not like having new restrictions added when I send it in for repair. If you can confirm that, and let me know the managers name (because before someone decided to override a decision when I had my P3 fixed, which was very bad service), I will send it in for repair.