Feathering System

[GravityHater]

To add to ultra runner..

you could go hold still the prop of a free turbine (like a king air) while the pilot started the engine and it would still start.

has anyone actually ever seen this done?

 

[bugchaser]

Seen it done and have done it. If you let the prop move at all, you better get outa the way! Have also forgotten to untie the prop and started the engine with the prop stopped.

 

[Ralgha]

deleted

 

[Alcatraz]

Ever shut down a PT6 and NOT feather the prop, then feather it after it's stopped? It's a strange sight to watch the blades change angle without rotation...

(especially when you're bored)

 

[Captain X]

Not really. The condition levers control fuel and propeller RMP. In the EMB-120, when the condition levers are fully retarded, that is the fuel cutoff position. During engine start the condition levers are pushed to the first detent which is (fuel on, propellers feathered). The engines will run all day in feather spinning at about 300 RPM(I think). When you are ready to taxi the condition levers are pushed to the next detent (min RPM). This is about 58% RPM or so (All RPMs are in % in the 120). When you are ready for takeoff the condition levers are pushed full forward. This will govern the props at 100% when the power levers are advanced for takeoff. We leave them there until we set cruise power. We will pull the condition levers back to about 85% NP for cruise. Without getting too technical, the condition levers basically are used to turn the fuel on or off to the engine. Then they are used to set propeller RPM. The "fuel mixture" is handled by the HMUs and EECs (manual and electronic fuel controls) which work automatically.

Gracious I miss the old gal! :frown:

 

[embpic1]

Gracious I miss the old gal! :frown:

I miss her too. I just got a new job and its been about 4 months since I have flown her.

 

[Singlecoil]

The connection is aerodynamic, meaning that the compressor spins so fast, that it, in turn, spins or turns the powersection.

Well, not exactly. In the interest of trying not to confuse the issue, how about we put it a little differently?

Rapidly expanding exhaust gasses moving across turbine blades powers both the propeller and the compressor. The propeller has a turbine section attached to it, and the compressor has a separate turbine section attached to the compressor. The same rapidly expanding gasses drive both turbines, one of which drives the propeller or power section of the engine, the other of which drives the compressor.

The compressor doesn't drive the the powersection.

 

[Bluto]

To add to ultra runner..

you could go hold still the prop of a free turbine (like a king air) while the pilot started the engine and it would still start.

Don't try this in the EMB-120, though. Rumor has it a mechanic tried this at our company and was thrown quite a distance when the engine, even at feather, overpowered him. As the story goes, they fired him for it, the second time it happened.
:laugh:

 

[atrdriver]

To add to ultra runner..

you could go hold still the prop of a free turbine (like a king air) while the pilot started the engine and it would still start.

THey say if you try it on an ATR-72 it will throw you over the terminal, although I don't think anyones ever been dumb enough to try it.

 

[Prop2Jet]

Never say never!