Originally Posted by
Squawk7700
We all know who and what you are... a showboat, who likes the sound of his own engine (or motor as you put it) !
Don't know who he is, but I am an aeronautical engineer (Chartered Engineer) who has (at various times) focused on both airworthiness certification and supportability engineering - a field that includes reliability and maintainability engineering (as it happens I have a masters degree in supportability engineering). I have been involved in the process of certifying aeroplanes many times, including undertaking the fault-tree anaylsis that determines the probability of single and multiple events leading to undesirable end-effects like death, serious injury and significant damage (this is a large chunk of the statistical process people have mentioned above). Each case is different, but these days it is a very common finding that (once you strip out the common-mode causes like fuel feed failure/leaks/contamination, maintenance-induced failures etc) the probability of a double-engine failure is much, MUCH lower than the probability of other events which would bring down a particular aeroplane. This is because modern engines have become so reliable and because they are much better instrumented with prognostic health monitoring systems so that a potyential failure is mitigated before it causes a disaster. And yes, I have seen cases where adding additional engines INCREASES the probability of aircraft loss due to risks like engine fractricide and uncontained fire/burst etc.
As a result in most cases it is simply more rational to spend effort/money on eliminating failure causes that are more probable than it is burdening aircraft with physical and financial features relating to much less likely events.
Sorry to contradict you on this Dick, because it's something you clearly have strong and passionate views on. But I am labouring under the distinct disadvantage of actually knowing what I'm talking about.
PDR