welll... we dont use them in the way you did here , we use it in "les" but not in "eux" and we just put it before "terrorisent" and still it dont make much sense bc we dont know who you are talkin abt , it would be better if it was "Mes amis et moi vont à New York en avion car les avions terrorisent les New Yorkais" if you were talking abt the plane terrorising the New Yorkers