Exactly my point, is it really over-torquing? The gear box is having no more than the maximum torque allowable go through it. The Ng is within limits. The ITT is within limits. What is the limiting factor? Is it the way the engine is mounted to the airframe? Is it purely a certification thing?
Of course not! Mr Cessna just throws these figures out there for no reason whatsoever! Who'da thunk a manufacturer knows jack siht about a half a million dollar piece of machinary? And trend monitoring? That only gets downloaded to the manufacturers to waste a base pilot time for half an hour every week.
Limits exist for a reason. They help engines make Full TBO.
