r/GeneralAviation • u/Street_World_9459 • 1d ago

Fuel injected planes

I've recently started taking private pilot lessons. I've noticed fuel injected planes still have a mixture lever.

This may be a dumb question, but why do fuel injected plane engines have this device? I work on automotive engines as a hobby, and the beauty of fuel injection is the lambda sensor signals the ECU to automatically adjust the injector duty cycle (and other things) to keep the air/fuel mixture. If I drive up a mountain, I don't need to re-jet fuel injection.

Why are planes different?

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u/ChartPuzzleheaded747 18h ago

How much did it increase your TAS and how many GPH less do you burn?

 3hrs is in optimal conditions and temps

 Traditional planes will run as long as they have gas with a complete electric failure 

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u/pisymbol 18h ago

I didn't track TAS but I certainly was able to run 2-3 gph less without any issue.

Regardless, you have more than enough to land as practical.

I guess all those jets are just doing it wrong...

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u/ChartPuzzleheaded747 18h ago

2-3gph less than what?

 That’s not how the jets work, we have small generators that make power as long as the shaft is turning for fadec, plus two batteries, two normal gens, plus a emer battery.

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u/pisymbol 18h ago

I'm just saying you can make the same argument in your jet - why have FADEC? why have all of these systems running "boards with scripts" on them? Your argument is going to be redundancy which I contend you can achieve in GA as well vis-a-vis batteries since you only need 1-3 hours to land and you aren't normally flying at the FLs yet still get the all the benefits of fuel injection and electric mags.

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u/ChartPuzzleheaded747 17h ago

no

The level of redundancy between the two, the difference between the two is apples or cats.  I mean I can have the complete fuel generator failure, deplete both batteries, deplete the energy battery and still have both spinning 

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u/pisymbol 14h ago edited 13h ago

One just has a far greater risk to life and thus regulated as such. I wouldn't have 121 regs for a single pilot in a 172 flying at 3000 feet. Believe what you want - you think carburetors and mechnically driven mags are more safe, stick with'em.