The best diagnosis of an engine is still probably comps & flying the aeroplane enough to become attuned to its vibrations & character.
My TCM engine is covered by this
SB that says you need a master orifice tool to calibrate your compression tester, and if your compressions fall below the limit set by the master orifice (40/80) then you have to do a borescope to internally inspect for the cause of leakage. The SB is a must-read, even gives pretty pictures to show what to look for!
I would want to do a regular inspection anyway, just to see - as you say - if any chronic problems are evident. Wouldn't anyone, if the technology was available?
My problem is still to find someone with the equipment to be able to fullly carry out TCM SB03-3 which says
"The purpose of the cylinder borescope inspection is to provide a visual method of examining the internal cylinder components and must be used in conjunction with the differential pressure test." By inference, does that means that perhaps we aren't maintaining our aircraft according to the manufacturer's recommendations etc.?
We are encouraged to operate by the advice given in engine manufacturer's manual, yet conveniently pick & choose which bits of maintenance advice from the same manufacturer we adhere to (check compressions) & ignore (borescopy)?
Cylinder head temps are nearly more important than EGT's, yet don't receive much attention. Its CHT issues that will cause cylinder issues & valve seat problems through overheating or shock cooling.
Agreed - hence the proposition (probably even fact) that CHTs are lower when running LOP than running at 25-50deg ROP as recommended by Some Engine & Aircraft Manufacturers! May I add also that apart from overheating issues (esp if CHTs > 425degF), the main issue is that CHTs are a surrogate marker for ICP - internal cylinder pressure, which is what causes cylinders to fail & self-destruct. It is interesting to note that the ICP curve follows the CHT curve i.e. tends to lessen the leaner you go. So LOP actually reduces CHTs and ICPs - all good things for cylinder longevity.