Flight schools and meat bomb aircraft suffer the worst cracking.
Folks,
Fact is, here in AU, with flying school engines running under AD/ENG/4, an 0-200 with 3500+ hours and still going strong, with nothing more but routine maintenance, is common.
Under the old (when CAA/CASA had some engine expertise) life extension programs , used by the small Regionals, regularly had TSIO-540 making 28/2900 hours, and again, having to change a cylinder was a rare thing, and usually a manufacturing defect. In the UK, I have had IO 540 over 3000h, running always low RPM/high boost.
Those of us who know what we are doing have replicated exactly what Walter Atkinson and John Deakin are talking about, long ago.Anybody with at least half a brain can see they are right.
I think the big problem with the cylinder AD is that FAA is now showing the same loss of technical expertise in management that happened in AU CAA, even before AU CASA was "invented", after yet another inquiry.
Remember, given the choice between a conspiracy and a cockup, go for the cockup every time, you won't often be wrong. A couple of FAA bureaucrats have backed themselves into a corner, and don't want to lose face.
Tootle pip!!