We do know that the A&P made an error but that in itself does not make him a cretin
POS that should be hung out to dry. Punishment of that sort should be reserved for those who purposely and intentionally deceive another for personal gain. The only way I can see this mechanic being guilty of that would be in collusion with the previous owner and possibly the FBO as well, because the mechanic himself stood to gain absolutely nothing from it. Now we're talking conspiracy and I'd gladly join in the witch hunt with the rest of you but we have no proof of any of it.
I'll tell you one thing - if the FAA were brought in on this it would implicate and cause discomfort to more people than just the mechanic. Because something here simply does not pass the smell test. This particular aircraft, based on the information we've been given here, has been operated illegally and in violation for at least the past five years. We're talking about a big can of worms here.
Furthermore, don't even get me started on this AD 2005-18-12. It's very similar to the Lycoming crankshaft AD - which in it's latest iteration is
2012-19-01. In it they say that you "may" have a defective crankshaft in your engine that could cause catastrophic failure but it's perfectly okay to use it until next overhaul or until the case is split for any reason or until it is 12 years old at which time it must be discarded - no ifs, ands or buts.
The Hartzell AD is the same - you have a dangerous propeller but it's okay to use it for ten years, regardless of where you park your airplane or how many flight hours you put on it.
These AD's that have calendar time limits are traps waiting to be sprung on unsuspecting owner/operators because obviously logbooks keep track of things using tach time.
I had the unfortunate job of telling the owner of a Piper Arrow that, although it had passed annual inspection with flying colors, his engine and, for all intents and purposes, his aircraft would be junk in three months time because the crankshaft was about to hit the 12 year mark. For some reason, prior to my coming along, no one had ever told him about it and he was not an actively engaged or educated owner. He had a copy of the original AD that had been mailed to the previous owner back in 2006 but apparently had never bothered to read it and the previous owner never bothered to inform him when he sold the airplane to him that he was going to need a new engine in 3 years.
But nothing illegal was done.