My usally tame budgie Bailey has become agressive towards my younger sister when I'm holding him he'll launch and bite her hard enough for it to hurt. He refuses to sit on her hand and only on mine. My other male is the same minus the agression.

 

Well he's going through a molt but he has quite bad molts, he loses ALOT of feathers and becomes rather grumpy.But right now all my sister has to do is move or make her clothes russle and he make "The grumpy budgie noise" that sounds sort of like a dolphin.

 

I've also noticed when he molts his flight feathers fall out while he flys, any other time of the month out of molting he fly's incredibly fast and no feathers fall out.

There is a product that you can get that may help him called Moulting Aid. Moulting is a natural part of their life, but Moulting Aid may help him. As I understand, you simply add it to his water.

I use Molt aid for my old man or I did till I lost the bottle, it's a great product. I find Harley is really grumpy (compared to just being grumpy) when when going through molt

Okay I'll look for that, he's not old he's about 2 years old. But he's grumpy when he's molting and always grumpy at night.