Sikorsky S-76: Ask Nick Lappos
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It can be a bit scary on here sometimes
Fact is what you see in ops can be quite scary. SAR 76 doing a winch from about 100' at an airshow and on departure overflies all the parked aircraft whilst accelerating from the hover. SAR 76 taxing onto a runway threshold for departure nil wind and taking off the "wrong way" if OEI accountability was to be a consideration. Taxi technique was often an eye opener - pull a hand full of collective, jam the cyclic forward and control the ensuing taxi with brakes.
did I leave any out?
Avoid imitations
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guillibell:
I believe the Queen's flight wrinkled their machine doing vertical takeoff engine failure simulations...
I think it was a C+
I believe the Queen's flight wrinkled their machine doing vertical takeoff engine failure simulations...
I think it was a C+
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Decu Total Fault On One Engine
I found this caution statement in the company EOP.
"To avoid an Nr overspeed, do not allow the torque of the
good engine to fall below 5% whilst lowering the
collective"
What would happen and why??
"To avoid an Nr overspeed, do not allow the torque of the
good engine to fall below 5% whilst lowering the
collective"
What would happen and why??
Due to the DECU TOTAL fault you should have an ungoverned engine. If that engine is stuck at a high power setting and you reduce the drag on the rotor system too much the Nr will climb above 107%.
Once you get it on the deck don't put the collective all the way down until you've pulled the bad engine to idle or off.
Once you get it on the deck don't put the collective all the way down until you've pulled the bad engine to idle or off.
Hi Slizer,
I believe that, with at least 5% of torque, the good engine DECU has still a limited authority to control the NR, while the "bad" one is under manual control.
I believe that, with at least 5% of torque, the good engine DECU has still a limited authority to control the NR, while the "bad" one is under manual control.
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S-76D question
The S-76D brochure features a claim of dual speed rotor. Can somebody expand on this for me? Thanks guys.
http://www.sikorsky.com/StaticFiles/...Links_1109.pdf
Among the S-76D helicopter’s features are all-composite, flawtolerant
main rotor blades; an advanced Thales avionics system and
autopilot; dual speed rotor with active vibration control; powerful Pratt
& Whitney Canada PW210S engines; a quiet mode for enhanced public
acceptance; and an optional Rotor Ice Protection System (RIPS) for
all-weather capability.
main rotor blades; an advanced Thales avionics system and
autopilot; dual speed rotor with active vibration control; powerful Pratt
& Whitney Canada PW210S engines; a quiet mode for enhanced public
acceptance; and an optional Rotor Ice Protection System (RIPS) for
all-weather capability.
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Similar to what you see on the EC135/EC145 and a few other models, done principally for noise reduction. In the case of the S-76D it'll be 107% RPM for take-off/landing and flight above 4K, and 102% for cruise flight below 4K.
I/C
I/C
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Does anyone know who designed the S-76? Testament to it's classic lines is that it still looks very modern after all these years. I do think it has the nicest lines of all of them.
Hi guys,
Wondering about location and capacity of the S76 aux fuel tank systems or options?
Where do they go? Capacity? different options for different S76 models?
CofG issues?
Thanks
Thank you for the reply below sanus,
hf
Wondering about location and capacity of the S76 aux fuel tank systems or options?
Where do they go? Capacity? different options for different S76 models?
CofG issues?
Thanks
Thank you for the reply below sanus,
hf
Last edited by helmet fire; 7th Jan 2011 at 09:21.
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S76 collective dropping
Does anyone have any thoughts as to why the collective in a S76A++ could be extremely heavy to the point that the mag brake is unable to hold it in position?
This one machine out of 4 that I fly, the collective is very heavy from flat pitch all the way up to takeoff power, and getting increasingly heavy beyond 70% torque (aerodynamic load?? mechanical disadvantage??). I'd guess that there must be 10 lbs of force required at the end of the collective lever when moving it off flat pitch and close to 20 lbs of force needed to move it and hold it near takeoff power. Needless to say my left bicep is getting quite the workout.
If the force trim button is then released the collective will drop maybe 10% torque or more until the mag brake springs balances the force, then it does not drop any further. It's a DAFCS equipped bird and some of our pilots have resorted to using 3 cue mode temporarily to make small adjustments in power in the cruise as it is almost impossible to set power manually (pull power 10% TQ over desired power and hope that it falls back to the power you want!).
The mechanics seem to be completely clueless as to how to fix it. Since joining the company I've been told this has been an ongoing issue for years with this bird and I've been told that the mechanics' solution invariably has consisted of changing the mag brake unit when a pilot complains, yet it has done nothing to solve the problem. (Albert Einstein's definition of insanity?)
There is no collective to yaw coupling going on, the pedals feel fine, the controls are otherwise smooth and no noticeable fluctuations in hydraulic pressure going on. Any thoughts? Hydraulic restriction? Bad rigging? Bad MR spindles? Worn flight control bushings? Bad flight control dampers?
This one machine out of 4 that I fly, the collective is very heavy from flat pitch all the way up to takeoff power, and getting increasingly heavy beyond 70% torque (aerodynamic load?? mechanical disadvantage??). I'd guess that there must be 10 lbs of force required at the end of the collective lever when moving it off flat pitch and close to 20 lbs of force needed to move it and hold it near takeoff power. Needless to say my left bicep is getting quite the workout.
If the force trim button is then released the collective will drop maybe 10% torque or more until the mag brake springs balances the force, then it does not drop any further. It's a DAFCS equipped bird and some of our pilots have resorted to using 3 cue mode temporarily to make small adjustments in power in the cruise as it is almost impossible to set power manually (pull power 10% TQ over desired power and hope that it falls back to the power you want!).
The mechanics seem to be completely clueless as to how to fix it. Since joining the company I've been told this has been an ongoing issue for years with this bird and I've been told that the mechanics' solution invariably has consisted of changing the mag brake unit when a pilot complains, yet it has done nothing to solve the problem. (Albert Einstein's definition of insanity?)
There is no collective to yaw coupling going on, the pedals feel fine, the controls are otherwise smooth and no noticeable fluctuations in hydraulic pressure going on. Any thoughts? Hydraulic restriction? Bad rigging? Bad MR spindles? Worn flight control bushings? Bad flight control dampers?
There are many areas to look into.
I would start with checking the collective force with hydraulics in a hangar, with and without the anticipator cable (the one that runs to the FCU) attached. There is a max friction value for this cable in the manual.
On Ariel engines there is also a rather strong spring for the anticipator cable (just behind the aft avionic access door), someone could have installed the wrong spring in the past or at wrong position.
Check the lubrication state (and smooth function) of the "ramp" for the anticipator signal (top of baggage, just ahead of aft avionic access door). Since you say this comes with high CLTV.
Loosing about 10% Tq when turning off the CLTV trim at 120 KTS is about normal (IMHO), check the flight check manual, but having to pull more Tq than wanted to be able to get desired value sounds strange.
The CLTV system with DFCS is weak, this is confirmed by SAC people, and therefore sensitive for problems.
Strange you do not get E37 code on the DFCS in 3 cue, if the system has this much resistance????
CB
I would start with checking the collective force with hydraulics in a hangar, with and without the anticipator cable (the one that runs to the FCU) attached. There is a max friction value for this cable in the manual.
On Ariel engines there is also a rather strong spring for the anticipator cable (just behind the aft avionic access door), someone could have installed the wrong spring in the past or at wrong position.
Check the lubrication state (and smooth function) of the "ramp" for the anticipator signal (top of baggage, just ahead of aft avionic access door). Since you say this comes with high CLTV.
Loosing about 10% Tq when turning off the CLTV trim at 120 KTS is about normal (IMHO), check the flight check manual, but having to pull more Tq than wanted to be able to get desired value sounds strange.
The CLTV system with DFCS is weak, this is confirmed by SAC people, and therefore sensitive for problems.
Strange you do not get E37 code on the DFCS in 3 cue, if the system has this much resistance????
CB
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S76A Inflight Power Checks
I have a question about analyzing the data from an engine trend check in an S76A. And I figured somebody kicking around here probably could enlighten me!
We do in-flight power checks instead of the ground power check option. So it means a 30min power check every 50hrs with daily trend checks preformed in between.
You keep an average of the trend checks called the "rolling average" (last 20 +/- 5 checks), and there are 3 criteria used to determine if you have acceptable power or not.
I'm fine with 2 out of the 3 criteria.
1.) The "rolling average" (average of last 20 checks) can never be negative... OK
2.) The daily trend margin can never be less than 4% below the rolling average... OK
3.) And finally the one I'm confused with: The rolling average can not have deteriorated by more than the power margin established in the last 30min power check
SO...
say the last 30 min power check had a margin of +4
To what do you compare today's rolling average with to get the answer for the 3rd criteria?
The RFM is vague at best with the description. And the FSI manual words it a bit better
Where I've found the most help is a Customer Service Notice that Sikorsky put out in 1988... which mentions a "base line" (the 5th trend after the 30min check)
Is that what you are supposed to compare the rolling average to?
If so why isn't it in the RFM?
Thanks!
We do in-flight power checks instead of the ground power check option. So it means a 30min power check every 50hrs with daily trend checks preformed in between.
You keep an average of the trend checks called the "rolling average" (last 20 +/- 5 checks), and there are 3 criteria used to determine if you have acceptable power or not.
I'm fine with 2 out of the 3 criteria.
1.) The "rolling average" (average of last 20 checks) can never be negative... OK
2.) The daily trend margin can never be less than 4% below the rolling average... OK
3.) And finally the one I'm confused with: The rolling average can not have deteriorated by more than the power margin established in the last 30min power check
SO...
say the last 30 min power check had a margin of +4
To what do you compare today's rolling average with to get the answer for the 3rd criteria?
The RFM is vague at best with the description. And the FSI manual words it a bit better
Where I've found the most help is a Customer Service Notice that Sikorsky put out in 1988... which mentions a "base line" (the 5th trend after the 30min check)
Is that what you are supposed to compare the rolling average to?
If so why isn't it in the RFM?
Thanks!
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jibboo,
You came to the right place, I wrote that gibberish, or at least was principal author, but by the time the tech pub writers finished.......
The basic idea of Power Assurance is to be sure the engine will let you meet published performance. The trend method allows some daily wandering of the margin, called scatter, which is assumed to be merely statistical and not actually indicating an engine problem. The rationale for each:
1) means = The engine meets the min specification power.
2) note: The "daily trend margin" means any individual daily power margin check. Means = No daily check can be very much out of whack - this spells trouble, maybe the engine has a real problem, and the result greater than 4% from the average is beyond scatter.
3) Means = if the margin at low power is less than the margin at high power, if you really had an OEI event, the engine might not give you 30 min and 2 1/2 min power. This covers an engine that has a "negative slope" which means it has less margin at high power than at low power.
Make any more sense?
You came to the right place, I wrote that gibberish, or at least was principal author, but by the time the tech pub writers finished.......
The basic idea of Power Assurance is to be sure the engine will let you meet published performance. The trend method allows some daily wandering of the margin, called scatter, which is assumed to be merely statistical and not actually indicating an engine problem. The rationale for each:
1) means = The engine meets the min specification power.
2) note: The "daily trend margin" means any individual daily power margin check. Means = No daily check can be very much out of whack - this spells trouble, maybe the engine has a real problem, and the result greater than 4% from the average is beyond scatter.
3) Means = if the margin at low power is less than the margin at high power, if you really had an OEI event, the engine might not give you 30 min and 2 1/2 min power. This covers an engine that has a "negative slope" which means it has less margin at high power than at low power.
Make any more sense?