Sikorsky S-76: Ask Nick Lappos
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Xnr,
Are you practicing such failures with full right pedal in the air? If so, each time you raise or lower the collective, you change the tail pitch, because the pedal stops are not the pitch stops in most mid to high collective situations. It is not particularly wise to fly this type of practice, I think, and is not in any training guide that I have seen, nor that Sikorsky has approved. Who's training guide are you using?
If such a stuck full right pitch situation took place, autorotate normally, set rpm at 100 with collective, and as you touchdown, you will be at 90 as you cushion. Don't trim the rpm low on descent, you need the rpm to make a nice touchdown. Touchdown nose up on mains first, any nose angle will be helped by wheel drag.
Are you practicing such failures with full right pedal in the air? If so, each time you raise or lower the collective, you change the tail pitch, because the pedal stops are not the pitch stops in most mid to high collective situations. It is not particularly wise to fly this type of practice, I think, and is not in any training guide that I have seen, nor that Sikorsky has approved. Who's training guide are you using?
If such a stuck full right pitch situation took place, autorotate normally, set rpm at 100 with collective, and as you touchdown, you will be at 90 as you cushion. Don't trim the rpm low on descent, you need the rpm to make a nice touchdown. Touchdown nose up on mains first, any nose angle will be helped by wheel drag.
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Nick
This conversation is a result of a bunch of pilots discussing worst case senarios.
They are not part of any training guide.
I know the chances of it happening are next to nothing.
I asked you mainly because I thought that it might be something you would have played with during certification.
T/R emergencies can get complicated in themselves but add the collective to yaw coupling and the fact that the S76 has a very powerful T/R and the situation worsens.
Thanks for your input ....lets put this one to rest.
Can I ask you one more question.
When the S76 was certified for a Cat A approach ,was there any requirement to zero groundspeed the A/C before touchdown or was a run - on landing acceptable. The flight manual graph is a little vague and the written explanation ends with " Apply brakes as necessary. " We operate in and out of some small helipads (100' x 100' ). Basically I guess the question is," Is the aircraft cetified Cat A to such a landing site?"
Cheers
This conversation is a result of a bunch of pilots discussing worst case senarios.
They are not part of any training guide.
I know the chances of it happening are next to nothing.
I asked you mainly because I thought that it might be something you would have played with during certification.
T/R emergencies can get complicated in themselves but add the collective to yaw coupling and the fact that the S76 has a very powerful T/R and the situation worsens.
Thanks for your input ....lets put this one to rest.
Can I ask you one more question.
When the S76 was certified for a Cat A approach ,was there any requirement to zero groundspeed the A/C before touchdown or was a run - on landing acceptable. The flight manual graph is a little vague and the written explanation ends with " Apply brakes as necessary. " We operate in and out of some small helipads (100' x 100' ). Basically I guess the question is," Is the aircraft cetified Cat A to such a landing site?"
Cheers
Last edited by Xnr; 19th Apr 2002 at 20:29.
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...to a stop!
The '76 can be brought to a stop/ zero airspeed, oei, touchdown.
Years ago our Songklha boys did it to a rig offshore after an engine failed. Mind you, into wind....low gross weight.... excellent pilot....
we do it in training given into wind....low gross weight..... etc.
Years ago our Songklha boys did it to a rig offshore after an engine failed. Mind you, into wind....low gross weight.... excellent pilot....
we do it in training given into wind....low gross weight..... etc.
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Good input, Donut King!
Xnr, The auto thing with a stuck right tail rotor is interesting. I don't know if it would fully trim at 80 knots in auto at 90% Nr but it would be very close. With a flare and some transmission drag moving the nose left, the landing is OK, in my opinion. The normal auto has a 90% touchdown or so, so I think it all works out nicely.
The Cat A landing needs more time than I have right now, because there are several procedures.
Xnr, The auto thing with a stuck right tail rotor is interesting. I don't know if it would fully trim at 80 knots in auto at 90% Nr but it would be very close. With a flare and some transmission drag moving the nose left, the landing is OK, in my opinion. The normal auto has a 90% touchdown or so, so I think it all works out nicely.
The Cat A landing needs more time than I have right now, because there are several procedures.
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Thanx for the input Donut King...
I realize that with a bit of pilot technique that it can be brought to a stop.....what we do with it and what it is certified for are sometimes 2 different things......
For example I don't see a vertical profile take off procedure in the Sikorsky flight manual but I have done quite a few vertical profiles.
My question was if the aircraft was certified to the stop or was a run-on landing acceptable for the Cat A certification.
I realize that with a bit of pilot technique that it can be brought to a stop.....what we do with it and what it is certified for are sometimes 2 different things......
For example I don't see a vertical profile take off procedure in the Sikorsky flight manual but I have done quite a few vertical profiles.
My question was if the aircraft was certified to the stop or was a run-on landing acceptable for the Cat A certification.
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Xnr,
There are about 5 different procedures for the S-76 family, with ground runs and without, all depending on the engine type, gross weight in the WAT curve, and exact procedures for the approach or departure. The basic one in the flight manual is the airport type procedure, where little attempt is made to shorten the landing distance, or the ground roll.
There is also a ground level heliport procedure, with no dip down after the cut on takeoff, and an elevated deck procedure with a dip below the helideck height after CDP. Both of these procedures are virtually zero ground roll on touchdown.
The FAA measures takeoff distance as that distance from the takeoff spot to clear a 35 foot barrier on climbout after an engine failure, and landing distance is that to clear the barrier on landing and then come to a full stop.
With some skill and practice, you can minimize the ground roll of even the airport procedure. You can land an S-76A on one engine at high gross weight, zero wind and roll less than one helo length fairly consistantly. The trick is to carefully control the speed on the way in, get to just above translational lift with almost no descent and at about 10 feet or so, then flare to kill off the speed, and cushion the landing. Practice with light weight, using partial torque to get the feel. Avoid too much nose up (10 degrees max at touchdown), too much rate of descent at touchdown, and too much rotor droop.
There are about 5 different procedures for the S-76 family, with ground runs and without, all depending on the engine type, gross weight in the WAT curve, and exact procedures for the approach or departure. The basic one in the flight manual is the airport type procedure, where little attempt is made to shorten the landing distance, or the ground roll.
There is also a ground level heliport procedure, with no dip down after the cut on takeoff, and an elevated deck procedure with a dip below the helideck height after CDP. Both of these procedures are virtually zero ground roll on touchdown.
The FAA measures takeoff distance as that distance from the takeoff spot to clear a 35 foot barrier on climbout after an engine failure, and landing distance is that to clear the barrier on landing and then come to a full stop.
With some skill and practice, you can minimize the ground roll of even the airport procedure. You can land an S-76A on one engine at high gross weight, zero wind and roll less than one helo length fairly consistantly. The trick is to carefully control the speed on the way in, get to just above translational lift with almost no descent and at about 10 feet or so, then flare to kill off the speed, and cushion the landing. Practice with light weight, using partial torque to get the feel. Avoid too much nose up (10 degrees max at touchdown), too much rate of descent at touchdown, and too much rotor droop.
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Thanx Nick
I am mainly interested in the S76A model as it has the least available OEI power.
So to answer my question, I guess the A model is not certified to the stop but with proper pilot technique this can be accomplished.
Sultan
Perfomance can be measured in numerous ways.
We like the speed, range, and the large unobstructed cabin of the 76.
The customer likes the low lbs./hr fuel burn.
A friend once told me that a 412 was a man's machine but the 76 gets the chicks.
Cheers
I am mainly interested in the S76A model as it has the least available OEI power.
So to answer my question, I guess the A model is not certified to the stop but with proper pilot technique this can be accomplished.
Sultan
Perfomance can be measured in numerous ways.
We like the speed, range, and the large unobstructed cabin of the 76.
The customer likes the low lbs./hr fuel burn.
A friend once told me that a 412 was a man's machine but the 76 gets the chicks.
Cheers
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Nick
What is the reason for the 1 min at idle restriction on the Allison/Rolls Royce engine if the aircraft has been shut down for more than 15 min.
I personally abide by this restriction, (I dont feel that big rush to get airborne) but there are a few who don't.
They say if the press. and temps are in the green you are good to go.
The only thing that I have ever heard that remotely makes sense is that this time allows for oil circulation in the engine.
Do you have a buddy at Rolls that can give us a definitive answer once and for all?
Cheers
What is the reason for the 1 min at idle restriction on the Allison/Rolls Royce engine if the aircraft has been shut down for more than 15 min.
I personally abide by this restriction, (I dont feel that big rush to get airborne) but there are a few who don't.
They say if the press. and temps are in the green you are good to go.
The only thing that I have ever heard that remotely makes sense is that this time allows for oil circulation in the engine.
Do you have a buddy at Rolls that can give us a definitive answer once and for all?
Cheers
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Xnr,
Thanks for the swipe at the Sultan, who should be sent to his room, preferably in a 412 so that he is gone longer.
I am reminded of the hurricane evacuation once done in the US Gulf, where the 76's evacuated twice the number of folks as compared to the 412, due to fuel capacity (range) and speed. The 76A carries more than the 412 Cat A at distances over about 100 miles (scarey distances for Bell drivers).
Regarding ground runs, the certification of the procedure is not really the whole issue. The tehnique I describe is acceptable. Also, we do have at least two zero ground run procedures for the 76A, but I'll guess that you don't have them.
Regarding the idle time, I will check on that with Dave Wright, the Chief Project Pilot.
Thanks for the swipe at the Sultan, who should be sent to his room, preferably in a 412 so that he is gone longer.
I am reminded of the hurricane evacuation once done in the US Gulf, where the 76's evacuated twice the number of folks as compared to the 412, due to fuel capacity (range) and speed. The 76A carries more than the 412 Cat A at distances over about 100 miles (scarey distances for Bell drivers).
Regarding ground runs, the certification of the procedure is not really the whole issue. The tehnique I describe is acceptable. Also, we do have at least two zero ground run procedures for the 76A, but I'll guess that you don't have them.
Regarding the idle time, I will check on that with Dave Wright, the Chief Project Pilot.
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Is there something more in the landing criteria than clearing a 35 foot barrier and stopping on the runway? I ask this because I'd think that with OEI you could stop 35' above the runway, just past the barrier, cut your good engine (not recommending this 
) and then zero speed auto onto the runway with no roll.
Maybe I'm just way out, and that is not possible at max AUW with normal pilot proficiency. Or maybe there is something more to the Cat A landing criteria?
Anyone?
) and then zero speed auto onto the runway with no roll.Maybe I'm just way out, and that is not possible at max AUW with normal pilot proficiency. Or maybe there is something more to the Cat A landing criteria?
Anyone?
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to xnr
Understand your question better now!
For me, Cat A. to a stop is only realistic given ideal conditions... into wind, good technique, no obstructions .....etc
As Nick L. stated, the flight manual assumes an airport/ controlled heliport environment.
Just a few thoughts for now!
Cheers!
For me, Cat A. to a stop is only realistic given ideal conditions... into wind, good technique, no obstructions .....etc
As Nick L. stated, the flight manual assumes an airport/ controlled heliport environment.
Just a few thoughts for now!
Cheers!
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Nick Lappos, ANOTHER S76 question....
A bit of a tech question for you.
S76C, when the number 1 engine is started (on battery) first, and then start the number 2 engine, all is well and everything starts fine.
If the number 2 engine is started first (again on battery) under the normal start prodcedure (generators on), the number 1 engine will not/is reluctent to start.
If you start the number 2 engine first, then deselect the generators, and then start the number 1 engine, it will start perfectly every time.
We cannot find any fault diagnosis charts etc in either the engine or airframe manuals which address this problem.
HELP!!!!
S76C, when the number 1 engine is started (on battery) first, and then start the number 2 engine, all is well and everything starts fine.
If the number 2 engine is started first (again on battery) under the normal start prodcedure (generators on), the number 1 engine will not/is reluctent to start.
If you start the number 2 engine first, then deselect the generators, and then start the number 1 engine, it will start perfectly every time.
We cannot find any fault diagnosis charts etc in either the engine or airframe manuals which address this problem.
HELP!!!!
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Helieng,
Sorry for the delay, the server rehost has not hit my home computer yet, just found this at work. I am checking with the S-76 Chief Pilot, Dave Wright for a more definitive answer, but here is my first shot:
I think it is a bad #2 primary contactor that makes a flakey #2 gen connection to the primary bus. All seems fine with battery bus power (as when you flip off the #2 gen). It could also be that the #2 gen is putting out too little power and the drain drags it down. How does #1 start when you run #2 engine up to flight idle, 107%Nr before you start #1?
Sorry for the delay, the server rehost has not hit my home computer yet, just found this at work. I am checking with the S-76 Chief Pilot, Dave Wright for a more definitive answer, but here is my first shot:
I think it is a bad #2 primary contactor that makes a flakey #2 gen connection to the primary bus. All seems fine with battery bus power (as when you flip off the #2 gen). It could also be that the #2 gen is putting out too little power and the drain drags it down. How does #1 start when you run #2 engine up to flight idle, 107%Nr before you start #1?
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Nick,
I am posting on behalf of a colleague, so I am relaying your replies to him.
He doesn't know how it would perform under those circumstances I am afriad.
Any further information from Captain Wright would be greatly appreciated.
"Some days you are the pigeon, some days you are the statue!"
I am posting on behalf of a colleague, so I am relaying your replies to him.
He doesn't know how it would perform under those circumstances I am afriad.
Any further information from Captain Wright would be greatly appreciated.
"Some days you are the pigeon, some days you are the statue!"
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Nick
Sorry I have been out of town for a while.
I am really interested in the procedures you have for zero ground speed OEI on the S76A.
Also, have you found out anything regarding the idle time requirement?
Cheers
Sorry I have been out of town for a while.
I am really interested in the procedures you have for zero ground speed OEI on the S76A.
Also, have you found out anything regarding the idle time requirement?
Cheers
Nick, RE S76 Flight Check Proceedures
Hi Nick, hope you might have time for the following question.
The S76A series Flight Proceedures manual states that "checkflights.... should be conducted near a landing field, when feasable, and during daylight hours under VFR conditions." Would you consider doing said flights at night/under IFR if not IMC (even multi crew) to be prudent, and within the bounds of interpretation?
Thanks,
Pitchlink
The S76A series Flight Proceedures manual states that "checkflights.... should be conducted near a landing field, when feasable, and during daylight hours under VFR conditions." Would you consider doing said flights at night/under IFR if not IMC (even multi crew) to be prudent, and within the bounds of interpretation?
Thanks,
Pitchlink