Originally Posted by
Lead Balloon
One of the reasons APS has detractors is that engine monitors and pilot education have exposed the variable quality of engine manufacture and maintenance.
The effort and cost it takes to get F/A mixtures balanced across cylinders shows how poorly balanced it is off the production line. Many new, certified and quality stamped cylinders need to be set up properly by the few remaining competent experts before fitment. Bushings made of cheese. Spark plug suppressors made of unicorn farts...
I can tell, on the first flight after maintenance, whether timing advance has been fiddled with and set correctly. Some engineers don’t like it when you say: “As a consequence of a change in CHTs and and in-air mag check, I can tell that you’ve advanced the timing on right magneto too far.”
Blocked injectors usually happen just after maintenance. Engineers don’t like it when you say: “The injector on 4 is blocked as a consequence of contamination introduced during your maintenance.”
Many new, certified and quality stamped cylinders need to be set up properly by the few remaining competent experts before fitment. Bushings made of cheese. Spark plug suppressors made of unicorn farts...
Can you explain what is set up before fitment?
I can tell, on the first flight after maintenance, whether timing advance has been fiddled with and set correctly. Some engineers don’t like it when you say: “As a consequence of a change in CHTs and and in-air mag check, I can tell that you’ve advanced the timing on right magneto too far.”
Is within tolerance too far? If my memory serves me correctly there is a tolerance of magneto to engine timing and also a tolerance of the internal magneto timing and considering there are two units - the total variation can be rather large, but certainly not defiantly "too far". In my honest opinion I believe you can not tell what you stated above, but that there is a change in indication most likely cause by a timing adjustment.
Blocked injectors usually happen just after maintenance. Engineers don’t like it when you say: “The injector on 4 is blocked as a consequence of contamination introduced during your maintenance.
I have known far more injectors to become blocked between servicing than just after maintenance, probably a ratio of 10 or 20 to 1!
Now if the nozzle has become blocked due to maintenance, it would be because the nozzle has been removed - just a random guess unless you have filter less aircraft and flow divider. Simply request at your expense to have the stainless fuel supply lines removed and cleaned when nozzles are removed if it is a common event for you.
A response to another post about LAME's dropping Spark Plugs - often that HT lead end ceramic breaks out in full, not seen it crack the other end.