Gosh, you lot have been having fun, haven’t you.
One of the key contributors to GA safety is that the standard GA piston engine is extraordinarily simple and can be operated and maintained by extraordinarily simple people. It can take quite a lot of counter-productive maintenance by ignorant maintainers, and it can take quite a lot counter-productive handling by ignorant pilots. It can take it for quite a while.
It can have the magnetos inadvertently set at 24 degrees BTDC rather than 22, because the maintainer has always used that mechanical protractor to set them and he don’t need no fangled electronic gadget to get it closer. That engine will run and put out lots of power. And keep running. The 10 or 20 degrees C extra CHT – who cares? It’s below redline on the gauge. You see: that proves mr maintainer’s wisdom right!
It can have the fuel flow out of the engine driven fuel pump set to the lowest rate permissible by the book procedure. The maintainer sets it there ‘cause the book says it’s OK at that setting and he’s gonna save fuel for the owner. That engine will run and put out lots of power. And keep running. The extra and unnecessary CHT at climb power – who cares? It’s still below redline on the gauge. You see: that proves mr maintainer’s wisdom right!
It can have plugs that pass a bench test and comply with manufacturers’ specifications, but don’t work as well as they could, or not at all at some power settings. That engine will run and put out lots of power. And keep running. The unnecessary load on the magnetos and the unavailability of the range of power setting options – who cares? It runs and the maintainer says the plugs are within spec. You see: that proves mr maintainer’s wisdom right!
It can be a CMI engine and set to 25/25 by the pilot in the climb, to ‘keep the engine cool’. That engine will run and put out lots of power. And keep running and climb. The loss of the enrichment function and the move of the PPP towards TDC, and the corresponding increase in CHT, who cares? It’s below red line on the gauge. You see: 25/25 has been proved right!
It can be run at 25 degrees C rich of peak. That engine’s putting out lots of power at that setting. And the maintainer says that lean of peak’s gonna wreck your valves. He knows it’s true, ‘cause he’s been doing this for decades. And the engine keeps on running below red line CHT. You see: 25 degrees C rich of peak has been proved right!
It can have an imbalanced fuel and induction system, such that each cylinder reaches peak EGT at different times. Doesn’t matter! The engine can put out lots of power rich of peak, and the maintainer says that’s the best place to run engine anyway. Lots of lovely lead to lubricate the valves. And the engine keeps on running. You see: that proves engines don’t need balanced fuel and induction systems!
LewC asked the - frankly inane - question:
All very interesting but a tad confusing.I suppose it comes down to which of the major protagonists,the Puffster,Jabba or yr right,would you want doing your next 100 hourly?
All I can say is, I don’t let people like yr right anywhere near my engines.
I get the timing fairy to set the magnetos to 22 degrees BTDC, using the correct equipment. And the CHTs go down 10 – 20 degrees C in the climb.
I get the fuel flow fairy to set the EDP so that the maximum fuel flow is at the top of book range, so that the CHTs go down further in the climb.
I fit plugs that work properly, as measured by actual performance at a proper range of mixture settings in the air rather than the snake oil of plug manufacturer
PR departments or a maintainer’s opinion as to their serviceability.
I don’t set 25/25 in the climb, because I want the fuel enrichment function enabled and I want the PPP as far away from TDC as practicable for the power I need.
I don’t set the EGT to 25 degrees C rich of peak, because I don’t want my engine running at the setting at which it’s getting the hardest flogging I can give it.
I fit injectors, in consultation with real experts, that result in all the cylinders reaching peak EGT at about the same point during the leaning process. And then I run the engine lean of peak when I want to, so that it’s very cool and not wasting fuel.
And, most importantly, I keep my engine as far away as I can from engineers who think that their decades of ignorance somehow validate their opinions.
That’s why I expect my current engine, like the previous one, to go way beyond TBO (if it was manufactured and assembled correctly).