TBM Idle Modes

[MattblackAviation]

Watching steveokinevo on YouTube, I can’t help but notice that he would always operate 100% on hi idle when he flew the TBM 850. Now I’m no TBM pilot nor do I fly any turboprop, but I was always under the impression you were in LO idle on the ground, and would switch to hi idle before takeoff. Any TBM pilot that could hopefully bring some more context?

 

[T/O w/FSII]

Watching steveokinevo on YouTube, I can’t help but notice that he would always operate 100% on hi idle when he flew the TBM 850. Now I’m no TBM pilot nor do I fly any turboprop, but I was always under the impression you were in LO idle on the ground, and would switch to hi idle before takeoff. Any TBM pilot that could hopefully bring some more context?

It really doesn’t matter. How much beta do you want? That’s a better question.

Higher idle = more. Better for stopping, but louder and more wear on the props if someone cares about that.


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[form810]

It really doesn’t matter. How much beta do you want? That’s a better question.

Higher idle = more. Better for stopping, but louder and more wear on the props if someone cares about that.


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The ONLY time for anything even approaching FULL beta in any TP is when decelerating after landing. And even then, neither the AFM nor the checklist typically call for or allow FULL beta, or even much beta at all. (That said, when one wants to back out of one's hangar, well sure, do yer yootoob thang, an' git dem clicks!)

 

[ERfly]

Chicks dig Beta!

 

[CoffeeIcePapers]

I rarely used high idle on the king air. In the 350, I would use it to move the airplane from a complete stop because it would bypass the stupid prop pitch solenoid that would surge the airplane if it went over a certain throttle position on the ground. In flight, I used it a couple of times for a short field landing for faster reverse response.

TBM might be different, since it’s single engine.

 

[knot4u]

I've always thought turboprops of any kind always operate at 100% because that's their happy place, same with helicopters. If you need more power add more fuel, the RPM should stay constant. But I'm just a dumb mechanic.

 

[T/O w/FSII]

I've always thought turboprops of any kind always operate at 100% because that's their happy place, same with helicopters. If you need more power add more fuel, the RPM should stay constant. But I'm just a dumb mechanic.

Not all turboprops are the same and the worlds most common turboprop motor the PT6 works like a normal piston engine. More fuel = more RPM.

 

[MattblackAviation]

I rarely used high idle on the king air. In the 350, I would use it to move the airplane from a complete stop because it would bypass the stupid prop pitch solenoid that would surge the airplane if it went over a certain throttle position on the ground. In flight, I used it a couple of times for a short field landing for faster reverse response.

TBM might be different, since it’s single engine.

Then the reason could be that in a SE turbo prop some manufacturers recommend 100% to help power systems, and because your King air was a twin it didn’t need all that power. Seems like a reasonable reason.

 

[CoffeeIcePapers]

Then the reason could be that in a SE turbo prop some manufacturers recommend 100% to help power systems, and because your King air was a twin it didn’t need all that power. Seems like a reasonable reason.

Definitely.

 

[knot4u]

Not all turboprops are the same and the worlds most common turboprop motor the PT6 works like a normal piston engine. More fuel = more RPM.

What does the prop governor do?

 

[T/O w/FSII]

What does the prop governor do?

The same thing as a 182


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[knot4u]

The same thing as a 182


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So the rpm stays the same but you make more power? Why do we have constant speed propellers?

Not all turboprops are the same and the worlds most common turboprop motor the PT6 works like a normal piston engine. More fuel = more RPM.

 

[T/O w/FSII]

So the rpm stays the same but you make more power?

Sigh. The guy who doesn’t know how the most popular turboprop engine on the planet works compared to how he thinks it works is arguing with me. Why am I not surprised.

Try going to google a PT6 and then a Garret turboprop motor and we’ll talk once you have had some education.

 

[knot4u]

Sigh. The guy who doesn’t know how the most popular turboprop engine on the planet works compared to how he thinks it works is arguing with me. Why am I not surprised.

Try going to google a PT6 and then a Garret turboprop motor and we’ll talk once you have had some education.

Tell me why we have constant speed props and governors? RPM does not limit power, temp does. But you know that, maybe you forgot. You can spin a King Air prop in flat pitch up until it tosses a blade and rips the engine off the wing but it's not going to make enough thrust to get you off the ground.

 

[gliderboy]

Air conditioning - in hot climates engine can run hotter at low idle.

 

[Roger Roger]

I can think of scenarios where you would run at high idle but I don’t know why you would do it every time.

 

[knot4u]

.

 

[MattblackAviation]

Something I find interesting is the TBM 940. With the single lever operation, you have no choice but to always operate in Hi idle.