i had the same problem a while back. It was one of 2 things. Either the failsafe position is gear up or the last time it was switched off the gear was up, in which case you need to cycle the gear a couple of times and then switch ithe rx off with the gear down. It sounds more like the failsafe in your case if it's always doing it.

Mine was the latter. I had to put the model in the car above another one and i had to retract the gear and then turn it off to get it to fit. I'd then turn it on and lower the gear and switch it off again until i was ready to fly. When it came round to flying i'd turn it on and the model dropped on it's belly and then the gear lowered again. I forgot to hold it a few times when turning it on, untill i realised what was happening.

Duncan