Basically, the line of causation of the mishap has to pass through a metaphorical block of Swiss cheese, and a mishap only occurs if all the holes in the cheese line up. Otherwise, something happens (planned or otherwise) that allows you to dodge the bullet this time.
Meaning a) it's important to identify places where firebreaks and redundancies can be put in place to guard against failures further upstream, and b) it's important to recognize times when you had a near-miss, and still fix those root causes as well.
Which is why the "retrospectives are useless" crowd spins me up so badly.
I mentioned this principal to the traffic engineer when someone almost crashed into me because of a large sign that blocked their view. The engineer looked into it and said the sight lines were within spec, but just barely, so they weren't going to do anything about it. Technically the person who almost hit me could have pulled up to where they had a good view, and looked both ways as they were supposed to, but that is relying on one layer of the cheese to fix a hole in another, to use your analogy.
As Ops person, I've said that before and it's mainly because most companies will refuse to listen to the lessons inside of them so why am I wasting time doing this?
To put it aviation terms, I'll write up something being like (Numbers made up) "Hey, V1 for Hornet loaded at 49000 pounds needs to be 160 knots so it needs 10000 feet for takeoff" Well, Sales team comes back and says NAS Norfolk is only 8700ft and customer demands 49000+ loads, we are not losing revenue so quiet Ops nerd!
Then 49000+ Hornet loses an engine, overruns the runway, the fireball I'd said would happen, happens and everyone is SHOCKED, SHOCKED I TELL YOU this is happening.
Except it's software and not aircraft and loss was just some money, maybe, so no one really cares.
Was a FMECA (Failure Mode, Effects, and Criticality Analysis) performed on the design prior to implementation in order to find the single points of failure, and identify and mitigate their system level effects?
Evidence at hand suggests "No."
Where do you think it will fit on the list?
The bad contact with the wire was just the trigger, that should have been recoverable had the regular fuel pumps been running.
DamnInteresting•1h ago
bmelton•17m ago
A lot of people wildly under-crimp things, but marine vessels not only have nuanced wire requirements, but more stringent crimping requirements that the field at large frustratingly refuses to adhere to despite ABYC and other codes insisting on it
Aurornis•3m ago
The good tools will crimp to the proper pressure and make it obvious when it has happened.
Unfortunately the good tools aren't cheap. Even when they are used, some techs will substitute their own ideas of how a crimp should be made when nobody is watching them.