I nearly had a major distaster flying my Mini Dragon off the Orme the other week. After flying at the usual break neck speed around the cliff top I took her up to dotsville whilst I had a chat with one of the locals. All of a sudden I had NO control. All I could do was watch it steadily spiral down picking up speed as she came down. It came banking in at high speed over the landing zone and I knew it was going to end badly. At about 2 metres high it suddenly shook itself and I regained control. This was followed by a rapid landing and it was packed up in the car whilst I had a cup of tea to calm down.
The subsequent investigation revealed the battery black wire had turned to dust and it fell apart in my fingers. I have read about this problem but I always wondered how I could check for this. I now know that it would have been obvious if I had visually inspected it or gently pulled it.
I recommend that if your model has been tucked away for a while give those black wires a quick inspection.
I did do the lottery that night but I think I had used up all my luck !