Favourite Ppc Question

[rotorheadrob]

Before bringing the generator on line N1 is set to 70% because the load from the generator could droop N1 below self sustaining rpm.

 

So if you forget to turn on the GEN, land set N1 to 70%, turn on GEN and continue with your day. If you roll the throttle back to detent you will be at aprox 62% and the sudden load because of the weak battery you will have from running boost pumps for that long on the battery could bring the N1 RPM bellow 58% which is the self sustaining rpm for the C20.

 

We don't turn the generator on at 100% because it could sheer the shaft.

 

rob

[DrDukeSolomon]

We don't turn the generator on at 100% because it could sheer the shaft.

 

Where does that come from?

 

the Duke

[412driver]

1. You have been cleared for t/o RWY 27 at YYJ. You are at 200lbs below GW with your SK76A and the wx is at IFR minimums.

 

What would you do?

 

 

I would politely prompt the non flying pilot to acknowledge the clearance!

 

 

Reject the clearance because with the SE RofC in the SK76A, you will not clear the hills in front of you.

 

Don't matter who accepts the clearance, if you depart, you'll be a smoking hole.

[06HeliMAN]

Not sure I really know the answer to this one, but here we go:

 

For most turbine engines used in helicopters, is more energy used in producing heat or into lifting and propelling the aircraft at whatever weight it may be?

[InspectorGadget]

The third part is that a HUGE portion of the potential power is used up in the gas generator stage to turn the compressor. So in essence, it requires most of its power to run itself. What little is left over is split up between turning the blades and covering the tailboom soot and wasted heat.

[xrkyle]

There aren't many machines out there that use thermal energy (i.e. gas turbines) that have a thermal efficiency greater than 50%. So for most turboshaft gas turbines, less than half the input energy drives the machine. What percentage is lost as heat depends on the turbine because there are many other factors that make it inefficient

 

[Phil Croucher]

The AS 355 F1 uses the same engine as the 206 (except the transmission comes out of the other end), and the generator is turned on at 100% in those. I would just turn the genny on. In UK, the 206 has a big light that flashes if it fails (just like in your car) so it's hard to forget it.

 

The reason you sit there at 70% in the first place is a hangover from the early days of the 206A where switching in the gen at low RPM would draw so much power it would cut the engine.

 

Phil

[DGP]

Since when if you have a gen failure in flight do you roll back to flight idle before hitting the gen reset...only one ping...

[deltacharlie]

You might shear the drive shaft of the Starter/Generator when it takes the load. I usually (unless I carry passengers) start a steep descend, collective to the floor, quickly roll the throttle off, gen on, then roll back and carry on.

 

Obviously this is only possible on a ferry flight, so hopefully I was smart enough to turn it on in the first place.

 

Next question, you're in your trusty Bell 206BIII, hydraulic power is lost, what other problems might you see?

 

Cheers

H.

Is this a joke? USE OF THROTTLE TO CONTROL RPM IS NOT AUTHORIZED. The only exception is an emergency overspeed and training. Even in the event of a GEN FAIL light illuminating the manual states to cycle the switch first, not roll the throttle.

[Winnie]

Is this a joke? USE OF THROTTLE TO CONTROL RPM IS NOT AUTHORIZED. The only exception is an emergency overspeed and training. Even in the event of a GEN FAIL light illuminating the manual states to cycle the switch first, not roll the throttle.

 

deltacharlie: I think you are misunderstanding the point of the "WARNING" in the book here, the statement you are quoting, is with regards to using the throttle to keep the Rotor RPM in a certain area, which is not allowed other than for real or practived emergencies, like tail rotor control failures.

 

In the case stated above, you are rolling the throttle to idle, entering an auto, then rejoining the needles again.

 

Cheers

H.