Before FADEC, did pilots need to adjust the mixture on airliners?

Rosstafari

Rosstafari

Hello, this is Orlando mayor Buddy Dyer
See title. Be aware that my knowledge is at the student pilot stage and based mainly off of the AIM/PHAK, ASA videos, and John and Martha King, so you might need to keep answers on an ELI5 level. Assuming the question even makes sense. Thanks!
 
Turbine engines do not have mixtures. However, conventional non fadec turbine engines do have hard limits on temperature, speeds, etc that can easily be exceeded by enthusiastic use of the lever. Fadec will generally keep the engine within the prescribed limits, and can also set the power to optimised levels for the phase of flight.
 
trafficinsight said:
And yet they had automatic mixture control... ;)

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Yeah, I don’t know the details, I seem to remember they had auto-rich, auto-lean, and manual modes? I do recall EK Gann talking quite a bit about adjusting mixture on the big radial propliners...
 
Roger Roger said:
trafficinsight said:
And yet they had automatic mixture control... ;)

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Yeah, I don’t know the details, I seem to remember they had auto-rich, auto-lean, and manual modes? I do recall EK Gann talking quite a bit about adjusting mixture on the big radial propliners...
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Oh boy, I could spend hours.... The mechanical genius of it is like a work of art.

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50 degrees lean of peak doesn't exist in turbine engines, the condition is either fuel on or off. FADEC should monitor the parameters of the engine and adjust as necessary or shut it down before exceeding limits. Whereas non-FADEC engines require a trained mammal to watch temps, pressures, rpms and to intervene before failure occurs.
 
CFI A&P said:
50 degrees lean of peak doesn't exist in turbine engines, the condition is either fuel on or off. FADEC should monitor the parameters of the engine and adjust as necessary or shut it down before exceeding limits. Whereas non-FADEC engines require a trained mammal to watch temps, pressures, rpms and to intervene before failure occurs.
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Don’t forget that adjustments in throttle position/power demand weren’t protected from the pilots stupidity/failure to monitor by a nanny computer that kept you out of trouble. FADEC or digital engine control depending on manufacturer provides all manner or protection for you to decrease probability of engine damage or resultant failure due to asking too much of the motor.

This was especially a problem in military aircraft where rapid manipulation of throttle/collective positions in all manner of changing dynamics is an issue.
 
The fuel in a turbine engine is metered by a fuel control unit, there is a mixture but it's based on throttle position, various pressures, and RPM.

Hydromechanical fuel controllers, like in older jets don't include protection for things like over temp, overspeed, stall etc.

Electro/hydromechanical, like in the good old CRJ-200 may have some of those protections or not, and may have some features like the CRJ's N1 speed control.

FADEC gives the computer full control over everything.

That's it in a pretty small nutshell.

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In a turbine the power lever (after a bunch of complex mechanisms whose exact kerjiggery depends on the engine- FADEC is just a very new version of this kerjigging) controls fuel flow into the engine.

The fuel/air mixture can’t really change. You put gas in, it mixes with the air coming through, goes bang and that’s it. If you add more fuel, more air will come through to match, and vice/versa if you take out fuel.
 
Rosstafari said:
See title. Be aware that my knowledge is at the student pilot stage and based mainly off of the AIM/PHAK, ASA videos, and John and Martha King, so you might need to keep answers on an ELI5 level. Assuming the question even makes sense. Thanks!
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Not to pile on, but you might find me funny (no one else does). Yes pre fedec we'd tell the turbine engine "here's some gas," or "no more gas." But even back then engines were expected to mix gas themselves. If those dirty engines are trying to angle for more money, tell them the NMB will never support that argument on 50 yrs of past practice. I don't ask them to fill their own oil tank, they shouldn't be asking me to mix their damn gas. Proles!
 
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