the whole concept is wrong
this is what happens when legislators try and design helicopters
EDML: “A helicopter does not have a lot of redudancy at all. There are hundreds potentially fatal single points of failure.“
quite right, and easy to make these parts reliable as long as the payload isn't wasted on bogus redundancy instead
riff raff: "...rotorcraft systems/structures are designed to provide a specific level of fault tolerance (zero, single, or dual fault tolerance) based on a criticality designation...."
but when you have 3 of something performing one function that all have to work then what do you call that?
You need a new category Triple Fault Intollerant perhaps?