High Idle/ Low Idle Condition settings for turboprops

[TopGun 0]

Hi all, Would someone be so kind as to elaborate on the proper high idle/low idle settings for the various phases of flight/altitude levels,etc for a typical turboprop such as the king air? (any web links for further info would be kindly appreciated also)Thanks for any responsesJ.C. (MYNN)

[Guest TerryT]

I believe the low idle is for ground operations while the high idle would be where you want to be just before you push the throttle forward for takeoff.Terry

[Guest allcott]

Terry is right, high idle is used in all phases of flight. Low idle is used only at startup.Allcott

[Guest allcott]

Terry is right, high idle is used in all phases of flight. Low idle is used only at startup... Ecept in FS-dom, where it can also be used to help keep things slow while taxing!Allcott

[Guest SHORT360]

Hi,It is also called GROUND FINE and FLIGHT IDLE with a secure crank to avoid by mistake to reduce to GROUND FINE while airborne. My cockpit is mainly based on real Short360 parts and its is marked like that.But it's the case in the almost all Turboprops. Rogerhttp://forums.avsim.net/user_files/64623.jpg

[TopGun 0]

Thanks for the responses.J.C. (MYNN)

[Guest Darren Howie]

G'day JCThe engine in the Shorts is entirely different to the PT6 which is in FS9 B350/200 and low/high idle is an option for crew to use.On the B200 we never use high idle ever.The only time you may consider using it is on very hot days to pump more air through the aircon to help cool the cabin after a turn around.High idle in our(Royal Flying Doctor Service) is not used on the ground as it causes enormous break wear when taxiing any long distances and means high beta use to control taxi speed and subsequent prop damage on stone littered strips.High /low idle is essentially an option you have on the ground and high idle has very few uses apart from cooling so in general is used rarely in the "real" world.HTHDarren Howie

[Guest Milamber]

Now I'm confussed....You just said the total opposite of those before you! Which is right?

[Guest allcott]

I think he was confirming use low idle all the time on the ground, advancing the condition levers to high idle for all aspects of flight. At least, that's how I read it.Allcott

[Guest Milamber]

Well re-read it then...I will quote:"On the B200 we never use high idle ever.The only time you may consider using it is on very hot days to pump more air through the aircon to help cool the cabin after a turn around. High idle in our(Royal Flying Doctor Service) is not used on the ground as it causes enormous break wear when taxiing any long distances and means high beta use to control taxi speed and subsequent prop damage on stone littered strips.High /low idle is essentially an option you have on the ground and high idle has very few uses apart from cooling so in general is used rarely in the "real" world."Unless I'm a total idiot who can't read (which as a lawyer I'm not), that paragraph says that High Idle is rarely if ever used and only for cooling purposes. So again that is the opposite of what other people have said, ie that High Idle is used exclusively except for during startup and/or ground operations. Which is it? Or is it that on the Beech turbo-props you do what he said and on others what the other people have said?

[Guest allcott]

I think Darren needs to reply to clarify but I read it very simply as low idle is used ON THE GROUND (my emphasis). I am almost positive standard operating procedure for PT-6 powerplants stipulates HIGH IDLE for all flight phases, with two separate checks on the full pre-flight checklist to make sure but I can't check that out at the moment. The consequences of selecting low idle in flight or at high power settings I wouldn't like to think about - for FS use it is simple: Low idle when taxiing, High Idle all other times.Allcott

[Guest Douglas K]

Both the SD3-30, SD3-60 and the King Air 350 use the PWC PT6A Large engine, and while the model numbers and horsepower ratings are different (PT6A-45/65/67R for the Shorts, PT6A-60A for the King Air 350), the operation of the condition lever is the same for Beechcraft and Shorts Bros flying machines equipped with the PT6A Large.Darren's description of condition lever use in the B-200 is correct, and it applies to the B-350 as well. The condition lever on airplanes equipped with PT6A engines does three things:1. Fuel Shutoff (or cutoff)2. Low Idle stop 3. High Idle stopThis is pretty much a no-brainer. On engine start, at the appropriate Ng speed you move the lever out of the Fuel Shutoff position, and place it in low idle to introduce fuel into the engine. After the engine lights off and stabilizes at idle, depending on where the condition lever is positioned (and fuel control rigging) the engine will idle at about 65-66% (low idle) or about 69-70% (high idle). Or at some value between 65% or 70% if the lever is positioned between the low and high idle stops.On the Shorts the lever is placed in ground idle and left there for all operations in flight and on the ground. The SD3-30 had a large aircycle machine and the air conditioning was just as efficient at low idle as it was at high. Our SD3-60-300 airplanes had aft freon air conditioning installed, which was completely independent of bleed air from the engines. For both airplanes, any extra cooling efficiency gainied by a small increase in bleed air flow as a result of using a higher idle speed was negligible.Darren's comments about idle speed, brake wear and the beta range are spot on. Consider that the King Air is a relatively light aircraft (when compared to a Shorts), with a high power to weight ratio and doesn't have any problem rolling after brake release. Also, the props are close to the ground and easily damaged. Just remember that the only thing affected by the condition lever on PT6A equipped airplanes is the idle speed and fuel shutoff. Also, that selecting anything other than the fuel shutoff position is OK in flight, and that taxi speeds are more comfortable and with regard to wear and tear less expensive with the lever in ground idle. >The consequences of selecting low idle in flight or at high power settings I wouldn't like to think about - for FS use it is simple: Low idle when taxiing, High Idle all other times.

[Guest Milamber]

Ok...Long and detailed explanation but break this down to the orginal question....IE what are the correct useage of the condition lever in FS (or real life) for the turbo-props? From the gist of your detailed explantion I get that it doesn't matter in-flight but to use Low Idle on ground but other people have said to use High Idle in flight and Low Idle on ground. Which is it? Does it matter?

[Guest Douglas K]

>Ok...Long and detailed explanation but break this down to the orginal question....IE what are the correct useage of the condition lever in FS (or real life) for the turbo-props?:)First, I want to stress that this information applies to aircraft equipped with PT6A engines only. Your question asks about turbo-props, those are airplanes that are equipped with a wide variety of engines, and most of them don't use a condition lever. For airplanes equipped with the PWC PT6A engine, the condition lever is used to turn the fuel on or off at the fuel control unit, and to change the idle speed from low to high within a narrow Ng speed range. And that's all it does.Once the fuel is on and the engine is running the only aircraft performance difference related to condition lever position of any real consequence is when taxiing. Taxiing with the levers in flight (high) idle produces a faster taxi speed and necessitates the excessive use of wheel brakes or the propeller beta range (the beta or ground fine range reduces prop blade angle to around 4 degrees and decreases thrust to slow the aircraft while taxiing). To avoid excessive brake wear the beta range is used as much as possible to control the aircraft's taxi speed. Another way to keep the speed down if you're faced with a long taxi and/or a takeoff hold is to taxi with only one engine running and start the other engine while you're holding. This also saves fuel.For the real King Air, it is very important to leave the lever in ground (low) idle while taxiing to reduce the speed as much as possible. The King Air is very light compared to a Shorts 330/360. The Shorts aircraft can weigh as much as 5 tons more for takeoff than a King Air 350, but the King Air has nearly the same horsepower as the SD3-30, and not too much less than the SD3-60-300. So you can appreciate that it is going to be pretty lively when you bring the props out of feather and release the parking brake. _____________________________________________________________________For the MSFS King Air, if you change the:beta_min = 15.2 //Minimum blade pitch angle for constant speed prop, (degrees)found in the aircraft.cfg file from 15.2 degrees to 4.0 degrees and then calibrate your throttle for reverse pitch using the registered version of FSUIPC you can taxi in a reasonably realistic fashion by using the beta range, but sadly, without the sound of the props changing pitch._____________________________________________________________________>From the gist of your detailed explantion I get that it doesn't matter in-flight but to use Low Idle on ground but other people have said to use High Idle in flight and Low Idle on ground.Which is it? Does it matter?

[Guest Darren Howie]

Hi GuysSorry about taking so long to post agin as i have been busy flying.Anyway to clarify.When starting in the RFDS B200's we place the condition lever to low idle.It is not placed into high idle at any stage of flight period unless doing a very short field landing.The reason for this is with the engine idling at the mid 60% range it has less spool time to start producing power in reverse.This is the only time on the B200 we ever,repeat ever use high idle apart from cooling purposes after start.I didn't know the shorts had a PT6 i thought it was a garret jigger?Mmmm you learn something every day!!Anyway i hope this makes it clear for our operation.Remember that every operator has there own slightly different procedures so what i say can be proved incorrect by say someone operating in Canada but the problems encountered by high idle really negate its use by most companies.All the best guysDarren HowieEX RFDS B200 Driver