Something new...
It is fairly recently that we have been advised to not just look at this or that unserviceable item one can operate with but also the interaction of various unserviceablities. Used to be you just looked for an item in the MEL and if it was there you were good to go. Now you are supposed to stop and think about the implications of coupled unserviceabilities, with updated MELs showing you how to do that.
A slightly different problem can come from trouble-shooting. Just going by these accounts, some of which seem to have been translated by software, the focus here was on the overheating RAT probe when the problem might have been some sort of WOW (Weight On Wheels) sensor that was giving an "air" instead of "ground" reading. That can have much more serious implications, of course. It would enable heat for the probe on the ground so that without the slipstream it would overheat but many other safety-critical systems would also be affected.
The human element can come into this in a big way. When you have a load of pax all waiting to go you can easily get "tunnel vision", just looking at the snag instead of pulling back to think about the whole system. It might be that the crew and the engineer were just thinking there was something wrong with the probe instead of backing off to look at why it was overheating.
I once had a problem with an engine refusing to light up. (We had been having this problem with tiny particles in the fuel causing a valve to stick closed, one that had to open to allow fuel to flow. We had been advised we had a 5-micron filter protecting a valve with 3-micron clearances and presumably 4.999-micron crud.)
We did the two start attempts allowed, when this FADEC thingy just meant pushing a button and waiting for stuff to happen. No happenings so we sent the pax back to the lounge and called the engineers.
They opened the cowling and started tapping on the offending valve housing with me still in my seat. The leader of the engineering team was leant over my shoulder pushing the start button while his assistent was out there whanging away, totally focused on getting this thing running.
I had some idea in the back of my mind but I couldn't quite get hold of it... Beyond the obvious one of getting out of there and leaving the machine in the hands of the engineers, I mean. No, there was something really, really dumb about this but what was it?
After two more tries the tapping succeeded beyond their wildest dreams! The valve went from stuck closed to stuck wide open so that the ITT wrapped all the way around and people out there on the ramp started running around and waving. (We couldn't see it from the cockpit but there was a plume two metres long of bright flame coming out the jet pipe!)
I pulled the power lever into the cut-off position but nothing happened except for the engine note hanging loud and low with all red showing on the ITT. Hmm... Would it be a good idea to ask the engineer to move aside, that I needed to go back and get a glass of tea, that it really was "his" airplane anyway? Then I thought to use the firewall cut-off button. That did the trick.
The hot section of the engine had instantly been reduced to scrap, of course.
I come from a humble background so that was my big day, when I got to help spend $1.5 million...
About two seconds too late I got hold of my (rather obvious) idea that something that sticks closed could also stick open, as it did. Yes, we had let the pressure just lead us down a blind alley there, going for the quick fix that would let us get airborne.