Thanks Con-Trail for your answer, very helpful. That was the answer I was leaning towards myself, i.e the assymetric arm.
I am having trouble agreeing with you on the Jet assymetric thrust. My book says that:
"in aircraft such as the 747, failure of an outer engine causes greater yaw than loss of an inner engine, as the thrust line is further removed from the aircraft longitudinal axis"
This means that on a 4 engined aircraft, the outer engines must be the critical ones, and failure of an outer engine will cause greater yaw.I believe this is more correct as to what you have said.
What do you think?
Thanks again for your help Con-Trail
Spelunker.