Thruster Helicopter, Need Help Keeping it in the Air!

Ive made a helicopter from the wonderful tutorial here: http://www.youtube.com/watch?v=mrdunp-uhdQ
He made a tutorial to lock the helicopter in the air, but thatsn ot what im looking for…
I want my helicopter to constantly lock the Z Axis, so it floats in the air and i can control it in the air, but i can find a way to do it.
Does anyone know how to achieve this? Thankyou very much

Turn off orient locally on the thrusters. And why did you make two threads about basically the same question? We have 2 question mega threads but you managed to miss it twice.