Just to underline this point, in light of the two comments after it.... 750mm rotor disc is NOT A TOY indoor heli! Chair legs, sofa, etc.... it would have done far worse damage to you if it had got you.
I have owned 4 of them (450 class heli's) and I don't even spin them up indoors without first "neutering" them with 0 pitch AND strapping them down, even that is only done of rare occasions to test the gyro is correctly wired/reversed. Normally if I'm working on it indoors I remove the main blades AND 2 motor wires.
As some one put it to me once, it only takes one mistake to ruin your life when working/playing with these things.
The "My little Jonny has a heli and he's always crashing it into the dog, LOL", type statements are from people that simply don't understand how fierce a 450 is. 450 crash into dog = dead dog or very expensive vet bill.