Turboprop Control Levers

bronco21016

bronco21016

I know H.T.M.L. (How To Meet Ladies)
I must be really stupid. For some reason I cannot for the life of me figure out what the levers do on a turboprop engine. My confusion is from looking at different aircraft that have different amounts of levers. The best example I can think of is the Cessna Conquest II vs. just about any other turboprop... like a King Air 90. The Conquest II has a throttle and a condition lever while a 90 has throttle, prop, condition lever. Why doesn't the Conquest have a prop control? There's no way those props aren't constant speed. Also what exactly does the condition lever do in a turboprop aircraft and how does the system work? While we're at it... How does the throttle work exactly? I guess that applies to all jet engines in general. Does it just meter how much fuel goes into the engine?

I'm in my school's Advanced Aircraft systems and we've been covering gas turbine engines. Unfortunately, we don't really get too specific on the systems or at least we haven't yet and so these are just a few of the questions that have been kinda bugging me. I've asked my instructor about why some aircraft only have two controls and others have three and he didn't really know and said he'd look it up. I know I'll get a faster response here.

Thanks!
 
In a two lever configuration the "throttles" are called Power Levers and the the fuel/prop controls are combined into Condition Levers. Condition levers are an on/off lever for fuel and the rest of their travel controls the pitch of the props.

In a three lever set-up, the "throttles" are called Power Levers, the prop controls are called the Prop Levers and the last set of levers are called the Fuel Levers. This set-up is generally found in older turboprop designs like the Twin Otter, older King Air 90s etc. The designers basically just took the design layout of piston engine multi's and replicated it. However, the Fuel Levers are, again, just an on/off switch (no mixture in a turbin engine). In this set-up they take up a lot of room, hence the design change to incorporate this function into the Prop Levers and call them Condition Levers.
 
The condition lever will usually have 3 positions ground idle, flight idle and cut-off/feather. The lever is used to set the gas generator idle speed (Ng AKA N1) for the particular operation you are doing. More simply put it functions to let the engine know you are just taxiing and don't need all the power it's capable of, or you are ready to take off and need all of that power. Don't quote me but I believe that some aircraft use the term high idle (flight) and low idle (ground).

Let's go fly. Step one hit starter and wait till 13% Ng, place condition lever into Ground Idle. Use Power Lever to taxi, works just like a throttle in a piston airplane just a little less responsive. Step two taxi into position and advance the condition lever to Flight Idle. You can hear and feel the engine spool up like it wants to go. Now use the Power Lever again just like a thottle. (I have heard of pilots taking off still in ground idle with no problems) Come back around and land. After touch down bring the condition lever back to ground idle use the Power Lever to reverse the prop and slow down. When you place the condition lever into ground idle you will hear the engine slow down and it makes it easier to taxi back to the ramp. Back in the chocks shut down avionics and generators/alternators pull the condition lever back to Cut-off Feather and engine shuts down and feathers the prop. This is also important in an emergency without auto-feather that you put the condition lever to cut-off in order to feather the prop so it's not out there making drag.

This was all written from the stand point of a PC-12 using a PT-6 engine. There is no prop control, it's all done in the governor at 1700 rpm for flight and 1000 rpm for ground.
 
I'm not familiar with how the PC-12 is set up, but it sounds like you are confusing ground idle and low idle. It would be impossible to take off in ground idle.

Ground idle- Power levers aft of the flight idle gate, but not in the reverse range. You're controlling prop pitch with the power levers. Move back into the reverse range and you are controlling fuel flow AND prop pitch with the power levers.

You are thinking of low idle. Condition levers on a King Air, for example, have three settings. Cutoff, low idle, high idle. You never need to use high idle for takeoff. I never have, and have only used it on landing in certain situations.

You have the same amount of power available in low idle as you do in high. All you are manipulating is the idle fuel flow, and thus gas gen. speed.
 
I think some of the ground vs. low idle is symantics and/or different manufacturer terminology. As stated earlier when you have three sets of levers, one is similar to the piston throttle (controls the amount of fuel going to the engine), one is a prop control, but the difference is in the condition (or fuel control) lever. In a King Air (or Caravan I believe), the lever has three positions: Cutoff, high (or flight) and low (or ground). Cutoff should be fairly obvious, the high and low positions set the engine turbine speed when the power levers are set to idle. For example, with the power levers set to idle, N2 would be 52% when in high idle, and 46% in low idle. Most of the time the condition levers are set to low idle. This aids in taxiing....lower power....less thrust....less dependent on brakes to control speed. The high idle position is used for short field approaches and touch and go's. Because turbine engines take longer to spool up, a higher idle speed means that power is available more quickly for either reverse or a go-around. As stated some airplanes combine the condition levers with the prop levers and they are generally referred to as condition levers. It's hard to get into specifics because there are several variations. I don't know if there are any FADEC turboprops out there, but they'd have only one lever per engine.
 
" I don't know if there are any FADEC turboprops out there, but they'd have only one lever per engine. I don't know if there are any FADEC turboprops out there, but they'd have only one lever per engine."

The SAAB 2000 has FADEC.
 
EatSleepFly said:
I'm not familiar with how the PC-12 is set up, but it sounds like you are confusing ground idle and low idle. It would be impossible to take off in ground idle. QUOTE]


The PC-12 is actually quite different than a lot of setups since it has no prop control. It always spins at 1700 rpm in flight. In a PC-12 the condition lever has 3 positions, feather/ fuel cutoff, ground idle, and flight idle. It only controls the NG (AKA gas generator speed of the engine). If you forget to go to flight idle the power is just less responsive on the take off roll as the engine has to spool up a lot more. I think it is similar to slow and fast idle on a king air.

The Swiss just decided to name things differently in the PC-12 to try and confuse people lol.
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EatSleepFly said:
I'm not familiar with how the PC-12 is set up, but it sounds like you are confusing ground idle and low idle. It would be impossible to take off in ground idle.

Ground idle- Power levers aft of the flight idle gate, but not in the reverse range. You're controlling prop pitch with the power levers. Move back into the reverse range and you are controlling fuel flow AND prop pitch with the power levers.

You are thinking of low idle. Condition levers on a King Air, for example, have three settings. Cutoff, low idle, high idle. You never need to use high idle for takeoff. I never have, and have only used it on landing in certain situations.

You have the same amount of power available in low idle as you do in high. All you are manipulating is the idle fuel flow, and thus gas gen. speed.
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ESF's got it and knows what he's talking about, at least he better for the equipment check outs that he has... :)
 
drummerboy said:
The Swiss just decided to name things differently in the PC-12 to try and confuse people lol.
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Roger that... sounds like it! So I stand corrected. Ground Idle in a PC-12 and Ground Idle in other airplanes are very different things. :)

jtrain609 said:
ESF's got it and knows what he's talking about, at least he better for the equipment check outs that he has... :)
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I wouldn't go that far. I've hung up my training captain hat for now, so I don't have to pretend like I know what I'm talking about anymore. ;) :panic:
 
bronco21016 said:
Does it just meter how much fuel goes into the engine?

Thanks!
Click to expand...

Yes, essentially. Airflow is obviously not throttled as in a piston. The power lever ("throttle") simply provides an input (one of several) to the engine control of how much thrust is desired. In older engines this would be a lever operating a valve on a complex hydromechanical unit; on a FADEC-equipped engine it's an electrical signal.
 
EatSleepFly said:
Ground idle- Power levers aft of the flight idle gate, but not in the reverse range. You're controlling prop pitch with the power levers. Move back into the reverse range and you are controlling fuel flow AND prop pitch with the power levers.
Click to expand...

Not sure what equipment you're flying, but that wasn't the case in the BE1900. In the 1900, the difference between the flight- and ground-idle pitch stops was controlled by a WOW function and had nothing to do with any gate in the power levers. If the power levers were at idle, then it was either flight- or ground-idle depending on whether you were weight on wheels or not. Lifting over the first gate put you into "beta," in which case the power levers were controlling prop pitch all the way back to the stop for the next gate at the "ground fine" position, and lifting over the second gate put you into the reverse range.
 
bronco21016 said:
I must be really stupid. For some reason I cannot for the life of me figure out what the levers do on a turboprop engine.
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If you're stupid - that makes two of us. After reading all the above posts, I still have no idea how turboprop levers work. I have a hard enough time figuring out what my single lever does.
 
Hello,
I'm not 100% on this, but I think that the "Q-400" is also equipped with FADEC, but has two levers. Power and condition/prop? I don't fly the thing, but I was talking to someone that has been studying up to get ready for ground school. According to him the "Q" power quadrant is identical to the earlier 10-300 series, but the big difference is that the condition/prop lever has no intermediate settings. In other words, just detents for various ground/flight regimes. He explained that in order to keep the single type rating much of the earlier 100-300 systems interfaces are identical, even if the function might be different it's transparent to the operator(pilot). The SAAB 2000 on the other hand requires a seperate type rating and it's EFIS system doesn't emulate the earlier SAAB even remotely. Although, it is a Collins system similar to the CRJ.
One last little tidbit...The power levers on the 1900 are also connected to the "3D Cam". This gadget allows not only changes in blade angle only (beta/ground fine), but also allows for a limited amount of fuel to be added when you continue moving up and aft into the second detent (reverse). This "may" come in handy, but typically reverse is rarely a requirement for where we fly. And, is often going to cause you troubles if you have a contaminated runway, crosswind or are single-engine, or in the worst case scenario...All the above...
Finally, there is an airplane that has been around for many years that uses a single lever for engine control and it's NOT FADEC...Hint..think Lockheed.

Regards,

ex-Navy Rotorhead
 
I don't know. You guys are confusing me. I just grab levers and start moving them until I find the one I'm looking for - or the Captain slaps my hand.
 
PCL_128 said:
Not sure what equipment you're flying, but that wasn't the case in the BE1900.
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Sounds like he was talking about a TPE-331

What makes this thread confusing is that there is no one correct answer. When it comes to piston twins, it's easy to say that the black knob is throttle, blue is prop, and red is mixture. That's pretty much a standard. However, there are too many variations in turboprop aircraft to give a simple answer.
 
Hey Airdale,
How did the XJET interview go? Also, I heard the first class of new hires going to the "Q" start ground school starts on 07 Nov.

Regards,

ex-Navy Rotorhead
 
BE19Pilot said:
Hey Airdale,
How did the XJET interview go? Also, I heard the first class of new hires going to the "Q" start ground school starts on 07 Nov.

Regards,

ex-Navy Rotorhead
Click to expand...

I didn't interview at XJet. Where I did interview, didn't go so well.

I do know that Colgan is hiring FO's for the Q, and assigning them class dates. Well I bid the Q back in July and guess what Colgan's response was to sending me to the Q. " We'll keep you in mind. " What a joke man. This Company is a joke, a big pathetic joke with a bunch of dumbass pilots for turning down the union. I'm out of here the first job offer. My conversation about the Q the other day sealed the deal.
 
Airdale,
Sorry to hear that...I remember where now too. I wouldn't be discouraged though, and there are plenty of other outfits out there hiring. Our current employer is so much run on crisis management on a shoestring that it defeats any prior planning. In the meantime, keep flying and keep applying.

Regards,

ex-Navy Rotorhead
 
PCL_128 said:
Not sure what equipment you're flying, but that wasn't the case in the BE1900. In the 1900, the difference between the flight- and ground-idle pitch stops was controlled by a WOW function and had nothing to do with any gate in the power levers. If the power levers were at idle, then it was either flight- or ground-idle depending on whether you were weight on wheels or not. Lifting over the first gate put you into "beta," in which case the power levers were controlling prop pitch all the way back to the stop for the next gate at the "ground fine" position, and lifting over the second gate put you into the reverse range.
Click to expand...


Read what he said again, he is talking about the 99(which, other than the stops, are using basically the same engine). :) How you described the 1900 is correct, he just went into more detail about the reverse. If you added to the end of your statement.."which will control prop and fuel", you both would have said the same thing.:D
 
tinman said:
Read what he said again, he is talking about the 99(which, other than the stops, are using basically the same engine). :) How you described the 1900 is correct, he just went into more detail about the reverse. If you added to the end of your statement.."which will control prop and fuel", you both would have said the same thing.:D
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It's been 6 years since I've flown anything with those confusing spinny things, so I'm lucky I can remember anything at all. :D
 
drummerboy said:
If you forget to go to flight idle the power is just less responsive on the take off roll as the engine has to spool up a lot more.
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While that is true, the biggest reason for flight idle in the PC-12 is for pressurization and environmental concern. Those two things take a lot of compressed air, with two engines, not a big deal. But at altitude with one engine, bringing the power lever back while at ground idle, you'd lose all pressure and any heating or cooling. Granted, even with flight idle it's not much, but it is better.
 
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