Dash7 condition lever/prop control?

[rotorhub]

Hi.

I just love this aircraft, thanks alot!

Does anyone have any info how the real condition lever/prop control works?

For my cockpit setup, I am about to configure the condition lever and the prop rpm on the same axis.
I am assuming that this is how it works in the real aircraft.

My question is; How many stages on the condition lever, and is the prop settings related to zones or gradual between min and max?

In regard of ground handling, how would this aircraft normally operate?

- Ground spoilers on?
- Taxi on 2 or 4 engines?

Regards
Arild

[Skyhawk_310R]

Well, not for this actual aircraft in detail, but I can tell you how they generally work on turboprop aircraft.

The condition lever for most turboprop aircraft when put to the full rear position both feathers the propellers and shuts off fuel flow. On some turboprop aircraft, a mid-range setting can cut off the fuel flow without feathering the prop.

You should also have a speed lever, that can put the engine into low speed and high speed modes. Low speed is generally used for startup and ground operations, such as taxi. On the C-130's I used the fly, the flight engineer had four buttons, one for each engine, that put them into low or high speed mode. On the turboprop I teach now, it is a single engine, and uses a speed lever that rotates forward to 100% RPM and retards aft down to 65% RPM, which is called low speed, and normal operations dictate one extreme or the other, but we do tweak the full speed setting a bit in flight to conserve fuel consistent with EGT, but that is entirely aircraft dependent. On most turboprop aircraft you put the speed lever full forward and let the plane fly at a 100% constant RPM setting.

Normally, you taxi with all engines powered on, but with some engines, or all engines, in low speed. A lot of that depends upon managing engine EGT (exhaust gas temperature) but also may be dictated by managing the generators which may not be able to provide sufficient power for the aircraft systems unless at least one engine is kept in high speed. High speed is used for takeoff and all inflight operations. So, that information should be provided in the aircraft's operations manual, which hopefully the vendor who made your virtual one provided to you. EGT is the best way to measure how hard the engines are working, and EGT is an excellent means of being aware of engine overheat or even engine failure. As I tell my students, "EGT never lies, but it does take its time!"

In looking at this photo of a real Dash-7 throttle quadrant:

http://www.google.com/imgres?sa=X&espv=210&es_sm=93&biw=1600&bih=1084&tbm=isch&tbnid=OmWsTZnC9Xz7lM:&imgrefurl=http://www.airliners.net/photo/Air-Tindi/De-Havilland-Canada/1520817/L/&docid=ossKgl68QLq3TM&imgurl=http://cdn-www.airliners.net/aviation-photos/photos/7/1/8/1520817.jpg&w=1200&h=812&ei=u9yxUrbXEu-kyAHZ5oF4&zoom=1&ved=1t:3588,r:0,s:0,i:81&iact=rc&page=1&tbnh=174&tbnw=243&start=0&ndsp=34&tx=134&ty=80

I can see that the condition levers are labeled for the fuel shutoff at the rear position, so this tells me that the Dash-7 system has the pilots go full aft to shutdown the engines and feather. The reason is that you do not want the props in feather with the engine still running as that could put a tremendous degree of stress on the system. If you can put all engines in low speed without losing adequate system power to keep the systems working properly, then that would be the way to taxi.

So, without knowing for certain, I would say you have two "settings" on your condition levers (normal ops and feather/fuel shutoff) and I was not able to find a photo of the real Dash-7 system that clearly showed the speed levers.

Spoilers are used to help slow down the aircraft after landing. So, I cannot see taxiing with the spoilers deployed. Like I wrote, you use low speed to control taxi speeds.

The throttles simply control the fuel flow to the engine, which are synched up with torque. So, you reference torque (or TIT depending upon how the aircraft is designed) as you advance the throttle. Torque is a measure of power output. RPM is a measure of propeller rotational velocity. On a piston engine complex aircraft (like a Cessna 310 or Baron) each work in harmony to control actual thrust. But, in a turboprop, it is generally more straightforward to leave the speed lever at 100% and use the throttles to control torque to meter power (also described as thrust).

Hope this helps!

Ken

[bstolle]

1. You should also have a speed lever, that can put the engine into low speed and high speed modes.
2. On most turboprop aircraft you put the speed lever full forward and let the plane fly at a 100% constant RPM setting.
3. Normally, you taxi with all engines powered on, but with some engines, or all engines, in low speed.
4. The reason is that you do not want the props in feather with the engine still running as that could put a tremendous degree of stress on the system.
5. Spoilers are used to help slow down the aircraft after landing.
6. So, I cannot see taxiing with the spoilers deployed. Like I wrote, you use low speed to control taxi speeds.

1. There are no speed levers in the Dash 7 (or any other PT-6 engined plane I know)
2. You never let a PT-6 powered plane (e.g. Dash7, Dash8) run at 100% RPM except during take off.
3. On the Dash7 you most of the time taxi with the two inboard props feathered (and the Dash8 with one prop feathered)
4. Not correct. See #3.
5. Spoilers are used to destroy lift to increase the weight on wheels after touch down, they are too small to add an significant amount of drag.
6. The spoilers on the Dash7 and Dash8 have no effect on the taxi speed. Before take off you arm the spoilers during taxi and they immediately extend. (they automatically retract with power application)

@Arild,

Moving the conditon levers full forward (position MAX) selects high RPM and you decrease the RPM by moving the condition levers aft until you hit the MIN stop.
IRL you have to lift the condition levers to be able to put them below min RPM into low flow, and again to move them into feather and fully aft into the fuel shutoff position.

[Tube and Rag]

1. There are no speed levers in the Dash 7 (or any other PT-6 engined plane I know)
2. You never let a PT-6 powered plane (e.g. Dash7, Dash8) run at 100% RPM except during take off.
3. On the Dash7 you most of the time taxi with the two inboard props feathered (and the Dash8 with one prop feathered)
4. Not correct. See #3.
5. Spoilers are used to destroy lift to increase the weight on wheels after touch down, they are too small to add an significant amount of drag.
6. The spoilers on the Dash7 and Dash8 have no effect on the taxi speed. Before take off you arm the spoilers during taxi and they immediately extend. (they automatically retract with power application.

2. Dash 8s don't have PT-6 engines, they have PT120s.
3. I worked thousands of Dash 7s back in the day (as well as jumpseated on several), and they always taxied with all four running. I've seen Dash 8s taxi on one engine; for agility reasons it is not the most desired method.
4. I think the OP is quite correct.

[bstolle]

2. Dash 8s don't have PT-6 engines, they have PT120s.
3. I worked thousands of Dash 7s back in the day (as well as jumpseated on several), and they always taxied with all four running. I've seen Dash 8s taxi on one engine; for agility reasons it is not the most desired method.
4. I think the OP is quite correct.

2. Sorry, meant P&W
3. I've got more than 2000hrs on the Dash7 and I never taxied with all 4 props unfeathered.
4. I think you are wrong.

[rotorhub]

Thanks for all your input! I will try to set zones on an axis to trigger condition and prop rpm settings.
I am unsure about the sequenze, but will experiment with FSUIPC.

Best regards
Arild




2. Sorry, meant P&W
3. I've got more than 2000hrs on the Dash7 and I never taxied with all 4 props unfeathered.
4. I think you are wrong.

[Skyhawk_310R]

2. Dash 8s don't have PT-6 engines, they have PT120s.
3. I worked thousands of Dash 7s back in the day (as well as jumpseated on several), and they always taxied with all four running. I've seen Dash 8s taxi on one engine; for agility reasons it is not the most desired method.
4. I think the OP is quite correct.

I appreciate the support. As I made very clear in my opening reply, I have not flown this aircraft, and so was commenting in general using two aircraft examples I have flown, trying to help someone understand a problem, but again made a point to say I had no experience in this exact aircraft type.

I suppose one can reply without making it appear he's going out of his way to attack someone. While I think you picked up on the same tone I did, I can honestly say this isn't the first time I've been on the receiving end.

One can only hope it becomes the last time, but we shall see.

Cheers,

Ken

[Tube and Rag]

I offer my apology to Mr. Stolle. After asking around, I am schooled that the prop on a free turbine--such as a PT-6--can be feathered while running.

[Skyhawk_310R]

I offer my apology to Mr. Stolle. After asking around, I am schooled that the prop on a free turbine--such as a PT-6--can be feathered while running.

I appreciate the information.

Cheers,

Ken

[Motormouse]

I offer my apology to Mr. Stolle. After asking around, I am schooled that the prop on a free turbine--such as a PT-6--can be feathered while running.

Actually it's necessary to start in feather to help control airflow
through the gas generator section of the engine, shutting down you can go straight to shutoff, prop will
feather by itself by spring action.

Ttfn

Pete

EASA licenced engineer