Sikorsky S-76: Ask Nick Lappos
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S76 C+ Engine Oscillations
Why do Sikorsky insist on using 'mixed mode' initially, for dealing with engine oscillations?
It would seem obvious to immediately utilise the manual reversion switch. If you have identified the correct engine 1st time; the oscillations will cease. If not, stick the other one into manual - Job done! This seems a lot more accurate and immediate than fannying around in mixed with very 'wishy-washy' results.
Have Sikorsky thought beyond the obvious, or is this a hang over from an earlier development?
It would seem obvious to immediately utilise the manual reversion switch. If you have identified the correct engine 1st time; the oscillations will cease. If not, stick the other one into manual - Job done! This seems a lot more accurate and immediate than fannying around in mixed with very 'wishy-washy' results.
Have Sikorsky thought beyond the obvious, or is this a hang over from an earlier development?
Just try not to be so cack handed with the collective, then the engines won't oscillate!
Avoid imitations
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We have many more problems with the FADEC and Arriel engines than with those nice old fashioned P&Ws with their EECs.
Why didn't Sikorsky standardise with the Blackhawk "throttle" quadrant?
Why didn't they call the tracks "normal" and "emergency"? It's far more logical to simply move a lever forward & aft in "normal" mode and pull it down into an "emergency" mode, rather than vice versa. It's the opposite logic on the C+.
The C++ engine control setup is apparently better designed.
Why didn't Sikorsky standardise with the Blackhawk "throttle" quadrant?
Why didn't they call the tracks "normal" and "emergency"? It's far more logical to simply move a lever forward & aft in "normal" mode and pull it down into an "emergency" mode, rather than vice versa. It's the opposite logic on the C+.
The C++ engine control setup is apparently better designed.
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?? Really??
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The 2S2 powered C++ quadrant is night and day to the C+. It couldn't possibly be simpler. Off, Idle, FLY. No more dual track, blue & amber light shows, or mixed mode.
Manual mode training switch is in same place, but FADEC controls when it will "allow" you to select manual control. Unlike the C+, you can't exceed any limits while training. The FADEC takes back control if you screw up (lowering collective with high power set).
Of course, if the DECU really gives up, it's blue-light-ops same as C+, but with incr-dinker thumb switch on collective.
Manual mode training switch is in same place, but FADEC controls when it will "allow" you to select manual control. Unlike the C+, you can't exceed any limits while training. The FADEC takes back control if you screw up (lowering collective with high power set).
Of course, if the DECU really gives up, it's blue-light-ops same as C+, but with incr-dinker thumb switch on collective.
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More like a proper, European one then? 
HOSS, since you are familiar with the C+ what is your opinion on Doc Cameruns suggestion with using the manual reversion switch?
I fully support the idea and used it "against FSI instructors recommendations" on my last sim trip with very good result. It is quick and positive and IMHO very simple way to "lock the fuel flow" to a given number for troubleshooting purposes.
CB
I fully support the idea and used it "against FSI instructors recommendations" on my last sim trip with very good result. It is quick and positive and IMHO very simple way to "lock the fuel flow" to a given number for troubleshooting purposes.
CB
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CB-
I'm certainly not as familiar with the + as the ++. I believe I know the answer, but, I have access to those that are probably the origin of the procedure. I'll ask.
HOSS
I'm certainly not as familiar with the + as the ++. I believe I know the answer, but, I have access to those that are probably the origin of the procedure. I'll ask.
HOSS
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SG76
Your logic is sound, but... Slightly missing the point; if you have intermittent fuel feed, there is no difference between what you're going to be able to achieve whether in Auto, Mixed mode or Manual mode.
Dependant on the exact cause of intermittent fuel you may get benefit in crossfeed, or more likely, in Prime.
I do think (sometimes due to uncertainty about the system), it's a big ask to expect pilots under duress to operate an emergency procedure that has no effect for the 1st 2-3 inches of movement (dependant on potentiometer thus stepper position). Much easier to just "Freeze the sucker", continue in proper Manual.
Doc
Dependant on the exact cause of intermittent fuel you may get benefit in crossfeed, or more likely, in Prime.
I do think (sometimes due to uncertainty about the system), it's a big ask to expect pilots under duress to operate an emergency procedure that has no effect for the 1st 2-3 inches of movement (dependant on potentiometer thus stepper position). Much easier to just "Freeze the sucker", continue in proper Manual.
Doc
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DC
I agree, it's easier to go straight into manual and I think that should be the prefered procedure. However reading your first post and seeing a lot of pilots getting confused when this procedure doesn't work in the sim, I just wanted to say that the procedure will not work with fuel induced oscillations.
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Having helped in the development of a generation of training simulators, let me make a carefully thought-out comment. Take GREAT care with procedures developed from flying a training sim. There is absolutely no reason to believe there is a connection between the oscillations as programmed by the sim engineer and the real cause of oscillations as experienced in the real aircraft. In other words, a sim might make oscillations by imposing them on top of the model of the engine, while the real aircraft experiences them from some internal imbalance that the sim might not at all replicate. Therefore, your home-grown procedure might fix the sim's symptoms, but be totally invalid in the real world.
Remember a simple rule: Training sims are designed to program YOU, they are NOT designed to replicate the real aircraft, in spite of pilot mythology otherwise.
Also, anyone who wants to develop flight manual procedures for a hobby should be forced to have their families fly in airliners flown by amateur pilots who figured out how to fly their aircraft by trial and error. This does not say that the procedure discussed here is invalid, but it does say that only an official endorsement from the manufacturer should be used to change the way we fly our aircraft. Anything else is as valid as Rush Limbaugh's sage advice.
Remember a simple rule: Training sims are designed to program YOU, they are NOT designed to replicate the real aircraft, in spite of pilot mythology otherwise.
Also, anyone who wants to develop flight manual procedures for a hobby should be forced to have their families fly in airliners flown by amateur pilots who figured out how to fly their aircraft by trial and error. This does not say that the procedure discussed here is invalid, but it does say that only an official endorsement from the manufacturer should be used to change the way we fly our aircraft. Anything else is as valid as Rush Limbaugh's sage advice.