Sorry LB I was taking your statement about a placard being labeled UNSERVICABLE at face value as you being a lawyer and everything, you would be speaking in precise terms. We even have a big placard that states that the tech log is not in the flight deck. Have a guess how often that procedure is not followed. The pressure to operate when all the paperwork and and equipment is not up to scratch is ever present and the young bloke in his first twin job is less willing to resist it than the crusty old captain. Trust me the pressure to operate when the paperwork is not up to scratch is still present even at the jet end of the spectrum. Its just that age and wisdom give you the willingness to stand your ground and tell the appropriate people to fix it or we don't go anywhere. If you have never operated in GA as a young pilot flying twins knowing that the next step is a regional or mainline position then anything you say, can and will be used as dunny paper.

Yes - in the interests of accuracy I merely quoted the relevant rule, LL. That said, It may be that individual airlines have exemption and approval to use a different methodology as part of their system of maintenance.

I’m well aware of the delta between the theory and the practice.

All I can do is observe that, if something goes wrong because someone incorrectly assumed a system was serviceable because it should have been but was not placarded unserviceable, the theory will become important and people will come under a very different kind of pressure.

(In one of those many collections of humorous aviation stories there’s the one - perhaps fictional or perhaps I’m not remembering it correctly - about the pilot who complained that the aircraft’s autoland system was not working properly, resulting in a heavy landing, only to find that the system had already been written up as unserviceable. Or perhaps the system wasn’t fitted at all. Hilarious when it only ends in a heavy landing...)

I can only agree with you in that regard. The Pelair Westwind and the KAL 747 cargo at are also testament to the dangers to the crew of an unservicable primary flight instrument. As you say the rules are black and white but the nebulous influence of pressure is what introduces the shades of gray.

It’s called the double bind problem.’’

https://en.wikipedia.org/wiki/Double_bind

No its called aviation.

Good news: The new, simple, outcomes-based rules will remove all the shades of grey.

Years ago flew a light twin single pilot Essendon to Albury. It had weather radar. Was somewhat mystified to notice all the mountains usually on the right (east) were displayed on the left (west) side of the radar screen.
On the way home back to Essendon, same weird display. Wrote it up in the maintenance release. The techs discovered the wiring to the radar was faulty and rectified the defect. That aircraft had been like that for months and not only did all the other pilots know about it (or maybe they never used the radar) but if they did, they didn't have the guts to snag it on paper.

Flew an Aero Commander for an Essendon operator Security Express. One of the pilots warned me the ADF only had five miles range. He was dead right.so I snagged it. The MR reply was Ground Tested Serviceable. Flew it again next day and same problem. Talked to the LAME who had signed it off as serviceable.

He said the ADF had been like that for months and all the pilots of Security Express were aware of it but had given up complaining verbally. Challenged the LAME why he had written "ground tested.. serviceable" when clearly he had not worked on it. He said he had contacted the aircraft owner who told him to sign it off as serviceable without looking into why the range was so poor. I don't know who owned that Aero Commander but he should have been hung out to dry by DCA.

Centaurus, in the case of the Aero Commander you talk about it should be the LAME and the Operator/AOC holder who are hung out to dry.

As an occasional hirer from a club aircraft fleet, I got used to the phrase: “It always does that!” when discovering a snag.

’Well I don’t get used to it. In fact I’m not very good at handling “grey areas” at all.

Luckily for me they had a very good and understanding engineering group who were always helpful and I was always happy to wait while things got “adjusted”, however I’m not sure if the CP was impressed. I’m sure he labeled me a pain in the arse.