Entering autos: discussion split from Glasgow crash thread
SAS: That lure certainly worked - I'm out of your peanut gallery it seems....
500: Can you tell me how operators like yourselves get insurance cover? The company I mean not the pilot. Do the insurers know you live inside the H/V curve?
RVDT The reason I asked apprentice and pilot was because you said you were a pilot and engineer, just thought it was a close coincidence.
It getting close to Chrimbo, I finish work on Friday for 18 days - it's a tough life.
Let's see if we can get along in the run up - to set the scene over the festive season. Ooops I ve done it now...heh heh...
500: Can you tell me how operators like yourselves get insurance cover? The company I mean not the pilot. Do the insurers know you live inside the H/V curve?
RVDT The reason I asked apprentice and pilot was because you said you were a pilot and engineer, just thought it was a close coincidence.
It getting close to Chrimbo, I finish work on Friday for 18 days - it's a tough life.
Let's see if we can get along in the run up - to set the scene over the festive season. Ooops I ve done it now...heh heh...
Originally Posted by [email protected]
Lowering the lever first will NEVER be a bad thing (unless you are in a low hover - the exception to prove the rule) because it will prevent further Nr Decay.
However, from a pure technical perspective that is not entirely precise, it will not prevent NR decay but it will reduce it.
If done very violently at a very high forward speed you might even be able to achieve a rotor stall when keeping the cyclic forward.
That said no one would do that in reality.
However, maintaining RRPM Comes from the tilted back (read flared) rotor disc vs. the flight path during autorotation. However a tilted back rotor disc will slow down the Helicopter. This has to be balanced in order to maintain the necessary airspeed and thus airflow through the disc. Lowering collective will do that. The sequence in which you establish this stable condition won't matter unless it takes too much time.
In which case both ways if done to the extreme (Only flare without lowering collective as well as only lowering collective without relaxing cyclic) would render you equally dead.
The strange thing in this discussion is that when reading carefully everybody here seems to have the same actions in mind. It's just whereupon the emphasis is laid where the difference lies.
All the more unfortunate that such a harsh discussion has ensued. As (primarily) an interested Reader I hope the emotions calm down a bit and the interesting discussion can continue.
@John Dixson: Thanks for the explanation! I found the discussion about technical limits interesting and therefore thank you for your contribution but I also understand concerns that this might be taken by some out of context (which I hope really doesn't happen).
Any such values will only apply for a certain situation and numbers will vary significantly depending on Type (I would expect see a drastic difference between a lightly loaded S-70 and an R-22 close to MAUW), Weight and circumstances.
Join Date: Dec 2011
Location: Oregon, US
Posts: 155
Likes: 0
Received 0 Likes
on
0 Posts
Yes they do, our premiums may be higher for that reason, I'm unsure.
As a company our accident rate over the past 10 years is lower than that of the industry single engine turbine accident rate of 2.96 per (100,000 flight hours) as reported by the HAI. (3 year moving average)
the #'s are all that matters to insurance companies
As a company our accident rate over the past 10 years is lower than that of the industry single engine turbine accident rate of 2.96 per (100,000 flight hours) as reported by the HAI. (3 year moving average)
the #'s are all that matters to insurance companies
Thread Starter
Join Date: Dec 2013
Location: Southern California
Posts: 14
Likes: 0
Received 0 Likes
on
0 Posts
Thank you, TC. The Best Kept Secret obviously does not apply to those of you trained and flying in the UK. But here across the pond we apparently have a different situation. The Best Kept Secret is not that cyclic must be applied quickly to stop and reverse falling rotor rpm. The "secret" is what will happen if the rotor rpm falls below the critical point for the particular make and model and the flight variables that exist at the time power to the rotor fails. Most helicopter pilots, from new to old timers, don't realize or believe that when this happens, there is absolutely no recovery from the situation, and that pilot and passengers are just along for the ride.
I have great admiration for the test pilots who gather the data needed to pinpoint the lower red line on the rotor tach of each make and model, and this lower red line must work for all possible combinations of load, DA, airspeed, c.g., etc., and must have some sort of cushion, too. I respect and teach pilots to observe these limits, and I have no desire to explore them with the engine(s) flamed out.
Almost every poster assumes the pilot will have both hands on the controls at all time. This is simply not true! As I pointed out in an earlier post, the collective is nothing more than a thrust control. All of us at times are not guarding the collective, and if a problem happens the cyclic should be brought aft without hesitation while moving one's left hand back to the collective.
Note that I say "Cyclic back and collective (lever) down simultaneously, or in that order." It is simply wrong in my opinion to prioritize the collective ahead of the cyclic, especially if one's left hand is not on the collective. This would mean not moving the cyclic until the left hand could find the collective and lower it. This would be a huge mistake.
And some posters say that the amount of aft cyclic should be determined by such things as airframe attitude, load, speed, DA, c.g., etc. Why? Why not treat cyclic back the same as lever down? When the engine fails do you stop and think about how far down you should lower the lever? Of course not. You lower it rapidly and fully, and then, if you determine that some pitch is needed for some reason, you raise the lever accordingly.
The same should be true for the cyclic...and even more so. There is no harm at all in starting the cyclic back immediately to stop, not slow, the reduction of rotor rpm, which is all that lowering the lever does.
The first group that needs to know about the Best Kept Secret is the old timers who have never heard of it. This obviously excludes those of you fortunate enough to be trained in the UK. The second group is the flight instructors who have never heard about it, and we've got plenty of them in the business (again, not in the UK). And the third group consists of the FAA and NTSB and the people who write and/or control the publications we depend on such as the PTS, the rotorcraft flight manuals and the slew of FAA-approved helicopter-related publications that do not even mention applying aft cyclic for any reason at all.
Pete Gillies
I have great admiration for the test pilots who gather the data needed to pinpoint the lower red line on the rotor tach of each make and model, and this lower red line must work for all possible combinations of load, DA, airspeed, c.g., etc., and must have some sort of cushion, too. I respect and teach pilots to observe these limits, and I have no desire to explore them with the engine(s) flamed out.
Almost every poster assumes the pilot will have both hands on the controls at all time. This is simply not true! As I pointed out in an earlier post, the collective is nothing more than a thrust control. All of us at times are not guarding the collective, and if a problem happens the cyclic should be brought aft without hesitation while moving one's left hand back to the collective.
Note that I say "Cyclic back and collective (lever) down simultaneously, or in that order." It is simply wrong in my opinion to prioritize the collective ahead of the cyclic, especially if one's left hand is not on the collective. This would mean not moving the cyclic until the left hand could find the collective and lower it. This would be a huge mistake.
And some posters say that the amount of aft cyclic should be determined by such things as airframe attitude, load, speed, DA, c.g., etc. Why? Why not treat cyclic back the same as lever down? When the engine fails do you stop and think about how far down you should lower the lever? Of course not. You lower it rapidly and fully, and then, if you determine that some pitch is needed for some reason, you raise the lever accordingly.
The same should be true for the cyclic...and even more so. There is no harm at all in starting the cyclic back immediately to stop, not slow, the reduction of rotor rpm, which is all that lowering the lever does.
The first group that needs to know about the Best Kept Secret is the old timers who have never heard of it. This obviously excludes those of you fortunate enough to be trained in the UK. The second group is the flight instructors who have never heard about it, and we've got plenty of them in the business (again, not in the UK). And the third group consists of the FAA and NTSB and the people who write and/or control the publications we depend on such as the PTS, the rotorcraft flight manuals and the slew of FAA-approved helicopter-related publications that do not even mention applying aft cyclic for any reason at all.
Pete Gillies
I have read with interest this thread and been lurking..... Too many new people, and I do not do well in crowds... 
One thing stands out though:
TC
You do realize the H/V diagram is NOT in the limitations section of many flight manuals right?
Not ignorant at all. I realize it is different in the UK, but there are a few of us who make a living flying inside that curve. Hence on this side of the pond it is often referred to as the "money curve". We do not go in there blindly, but with much forethought and risk mitigation as far as possible. As 500 stated it best:
For the record----I am on Pete Gillies side of the fence with the aft cyclic, have been for many years. It simply buys time and to be honest, my right hand is almost never off the controls.
See you in 14 pages.....
One thing stands out though:TC
As a consequence of ignoring sound technical advice as shown in the FRM, Operations and Limitations Sections.........prolonged operations in the H/V curve
PS: Describing the H/V curve as a "Disclaimer" is at least disingenuous, at most ignorant.
Every operator I know recognizes and respects the performance envelope put out there by the test pilots and engineers. However, staying out of the avoid curve is just not a reality to our industry. Like you said, we do our best to limit the time there, limit weight to increase options in the event something goes wrong, and we all do far more than minimum required maintenance.
See you in 14 pages.....
Join Date: Dec 2013
Location: Norfolk
Age: 67
Posts: 1
Likes: 0
Received 0 Likes
on
0 Posts
Pete
I think that non helicopter pilots such as myself initially visualise the control movements you describe as large, abrupt movements, when in fact nothing could be further from the truth. The various safety videos all make the point that the helicopter flying controls must be handled with authority but also with a light touch. So for example the cyclic controls should never need to be moved to their full extent in flight. I think it is the amount of aft cyclic movement required that is perhaps confusing people. The answer naturally depends on the individual circumstances at the time, the aircraft performance characteristics and the pilot's experience.
I had the good fortune to fly with an RAF instructor who made me form a ring around the joystick with my fingers and thumbs. He then flew a loop, barrel rolls to the left and right, and a stall turn, all without the joystick touching my hands, so demonstrating how sensitive aircraft controls actually are.
So when you say apply aft cyclic and lower the collective lever, you are not advocating pulling the cyclic back into your chest, it is a far gentler but authoratitive movement of the cyclic control back as far as necessary to deal with the immediate situation?
Until the tragic Glasgow crash, I had no idea of the consequences of an engine failure and main rotor stall in a helicopter. In my fixed wing mentality, I just assumed you pointed the helicopter at the ground, picked up speed and carried out an autorotation. The swiftness with which the main rotor rpm can decay and the absolute certainty that below a certain limit, it can never be recovered is quite shocking. Not a secret within the helicopter community, but something that few members of the general public are aware of.
I think that non helicopter pilots such as myself initially visualise the control movements you describe as large, abrupt movements, when in fact nothing could be further from the truth. The various safety videos all make the point that the helicopter flying controls must be handled with authority but also with a light touch. So for example the cyclic controls should never need to be moved to their full extent in flight. I think it is the amount of aft cyclic movement required that is perhaps confusing people. The answer naturally depends on the individual circumstances at the time, the aircraft performance characteristics and the pilot's experience.
I had the good fortune to fly with an RAF instructor who made me form a ring around the joystick with my fingers and thumbs. He then flew a loop, barrel rolls to the left and right, and a stall turn, all without the joystick touching my hands, so demonstrating how sensitive aircraft controls actually are.
So when you say apply aft cyclic and lower the collective lever, you are not advocating pulling the cyclic back into your chest, it is a far gentler but authoratitive movement of the cyclic control back as far as necessary to deal with the immediate situation?
Until the tragic Glasgow crash, I had no idea of the consequences of an engine failure and main rotor stall in a helicopter. In my fixed wing mentality, I just assumed you pointed the helicopter at the ground, picked up speed and carried out an autorotation. The swiftness with which the main rotor rpm can decay and the absolute certainty that below a certain limit, it can never be recovered is quite shocking. Not a secret within the helicopter community, but something that few members of the general public are aware of.
I'm certainly glad I'm not a TP, it would be so difficult to work out how to treat your dissertations.
I made my thoughts on the thread topic plain in page three of this thread, yet the moment I or anyone else pops their head above the parapet to suggest some courtesy towards Nick and John D then Rotorheads with an axe to grind try to make it a willy waving exercise. And a very unseemly one at that.
Join Date: Dec 2013
Age: 81
Posts: 316
Likes: 0
Received 0 Likes
on
0 Posts
May I suggest that design and manufacturing companies might care to provide a Short Works Course for pilots where they can visit for a week and sit alongside the team who are designing, proving and testing the product?
This might enhance understanding of just how much there is to learn and how Test Pilots are very professional team members following carefully laid out test procedures in cooperation with the entire team.
This might enhance understanding of just how much there is to learn and how Test Pilots are very professional team members following carefully laid out test procedures in cooperation with the entire team.
Join Date: Dec 2006
Location: UK and MALTA
Age: 61
Posts: 1,297
Likes: 0
Received 18 Likes
on
4 Posts
John Eacott - let's get at least one thing crystal clear. The Newfoundland S92 comments I made are based on the intimation that the P1 was continuing flight under the misunderstanding that his MGB had a run- dry capability.
This discussion was, and has been in the public forum since that event.
Someone, somewhere released that erroneous information.
If this is incorrect challenge it.
The "shocking" thing to do is ignore it. As you seemed inclined to do by diverting attention to me. My only interest in this is SAFETY. Safety by following the limits and procedures in the RFM.
My comments about Test Pilots is that when they speak or post it carries implied credibility. I do not believe JD deliberatley set out to convince people that there is more time to irreversible rotor decay than Peter Gillies surmised but I rather suspect that Peters very informative, safety competant post was like a red rag to a bull for the TPs who think numbers are their game.
HC is correct. TPs posting on here are subject to the same scrutiny as are we all.
As for you I have apologised twice, publicly for misunderstanding your post and coming across as rude. You have continued to stick it too me, with I might add, no substance to your posts whatsoever other than you believe my statements to be shocking.
What is shocking is considerable loss off life that may have been caused by ill advised, incorrect, unjustifiable bull**** spoken by those who should know better. So John Eacott, get off your self fed Dobbin, stop the one line rhetoric (one for you TC) and Chunder up whatever is in your guts that's eating you.
DB
This discussion was, and has been in the public forum since that event.
Someone, somewhere released that erroneous information.
If this is incorrect challenge it.
The "shocking" thing to do is ignore it. As you seemed inclined to do by diverting attention to me. My only interest in this is SAFETY. Safety by following the limits and procedures in the RFM.
My comments about Test Pilots is that when they speak or post it carries implied credibility. I do not believe JD deliberatley set out to convince people that there is more time to irreversible rotor decay than Peter Gillies surmised but I rather suspect that Peters very informative, safety competant post was like a red rag to a bull for the TPs who think numbers are their game.
HC is correct. TPs posting on here are subject to the same scrutiny as are we all.
As for you I have apologised twice, publicly for misunderstanding your post and coming across as rude. You have continued to stick it too me, with I might add, no substance to your posts whatsoever other than you believe my statements to be shocking.
What is shocking is considerable loss off life that may have been caused by ill advised, incorrect, unjustifiable bull**** spoken by those who should know better. So John Eacott, get off your self fed Dobbin, stop the one line rhetoric (one for you TC) and Chunder up whatever is in your guts that's eating you.
DB
Join Date: Dec 2006
Location: UK and MALTA
Age: 61
Posts: 1,297
Likes: 0
Received 18 Likes
on
4 Posts
I have had a couple of PMs calling for me to explain my comments in relation to the S92 and they have caused meto reflect.
Firstly, I in no why implied that Nick or JD had anything to do with the s92 demise.
What I am implying, and stand by, is the possibility that the crew were not in full possession of the facts which caused them to continue flying when their checklist said land IMMEDIATLEY.
The S92 RFM calls for an immediate landing when Oil Px hits zero. That does not mean the MGB will explode IMMEDIATLEY. It clearly must run dry for some period of time to allow for the landing. However, the limits are clearly stated.
If the P1 was fully aware of the nature of this limit, and the likely outcome if ignored, he would surely of ditched. After the events there was strong intimation that crews believed that MGB would run dry.
In this case, decaying NR limits. The limits are clearly stated in the RFM. However, this does not mean that one percent below that limit the NR is unrecoverable. There is a safety margin. However, for us pilots there is only ne limit applicable.
Now when JD choose to call Peters post wrong, due tothe conservative values Peter quoted, JD choose to expose us to the safety limit. This has the potential to perpetuate the misbelief that NR can be safely reduced below the RFM limit.
My post harsh and uncompromising but I hope those of you who view safety asi do will see the reason behind this.
Once again I apologies if I gave the impression that ZJD was responsible or the 92. That was not my intent.
DB
Firstly, I in no why implied that Nick or JD had anything to do with the s92 demise.
What I am implying, and stand by, is the possibility that the crew were not in full possession of the facts which caused them to continue flying when their checklist said land IMMEDIATLEY.
The S92 RFM calls for an immediate landing when Oil Px hits zero. That does not mean the MGB will explode IMMEDIATLEY. It clearly must run dry for some period of time to allow for the landing. However, the limits are clearly stated.
If the P1 was fully aware of the nature of this limit, and the likely outcome if ignored, he would surely of ditched. After the events there was strong intimation that crews believed that MGB would run dry.
In this case, decaying NR limits. The limits are clearly stated in the RFM. However, this does not mean that one percent below that limit the NR is unrecoverable. There is a safety margin. However, for us pilots there is only ne limit applicable.
Now when JD choose to call Peters post wrong, due tothe conservative values Peter quoted, JD choose to expose us to the safety limit. This has the potential to perpetuate the misbelief that NR can be safely reduced below the RFM limit.
My post harsh and uncompromising but I hope those of you who view safety asi do will see the reason behind this.
Once again I apologies if I gave the impression that ZJD was responsible or the 92. That was not my intent.
DB
Mea culpa, I failed to acknowledge your apology earlier: thank you for recognising that I had neither said nor inferred that of which you accused me.
I can only assume that you are disregarding the Canadian TSB Accident Report? I have emphasised the pertinent part which refutes your assertion about the P1s understanding of the S92 and my subsequent concern over your inflammatory comment about (I assume) Nick Lappos.
John Eacott - let's get at least one thing crystal clear. The Newfoundland S92 comments I made are based on the intimation that the P1 was continuing flight under the misunderstanding that his MGB had a run- dry capability.
This discussion was, and has been in the public forum since that event.
Someone, somewhere released that erroneous information.
If this is incorrect challenge it.
This discussion was, and has been in the public forum since that event.
Someone, somewhere released that erroneous information.
If this is incorrect challenge it.
1.18.6 Social Media
The internet has greatly increased opportunities for individuals to interact and exchange information and viewpoints. Internet forums, a form of social media,139 have become a widely popular source of information exchange. On one such internet forum, the S-92A generated an enormous amount of discussion. Starting in March 2000, before the S-92A went into commercial use, website visitors engaged in discussions about the introduction of the S-92A. Many of the individuals who posted on this website chose to remain anonymous. However, others such as one of Sikorsky's senior managers for the S-92A program, who was a regular contributor to the online discussion, chose to identify themselves. Over the course of several years, the subject of the S-92A's compliance with Part 29 was discussed at length among members of this internet forum. From these online discussions, it was evident that those involved understood that the S-92A did not have a run dry capability.
It was determined during the TSB investigation that at least one senior manager, and several other pilots at Cougar Helicopters periodically reviewed the material posted on the above mentioned internet forum.
The internet has greatly increased opportunities for individuals to interact and exchange information and viewpoints. Internet forums, a form of social media,139 have become a widely popular source of information exchange. On one such internet forum, the S-92A generated an enormous amount of discussion. Starting in March 2000, before the S-92A went into commercial use, website visitors engaged in discussions about the introduction of the S-92A. Many of the individuals who posted on this website chose to remain anonymous. However, others such as one of Sikorsky's senior managers for the S-92A program, who was a regular contributor to the online discussion, chose to identify themselves. Over the course of several years, the subject of the S-92A's compliance with Part 29 was discussed at length among members of this internet forum. From these online discussions, it was evident that those involved understood that the S-92A did not have a run dry capability.
It was determined during the TSB investigation that at least one senior manager, and several other pilots at Cougar Helicopters periodically reviewed the material posted on the above mentioned internet forum.
I can only assume that you are disregarding the Canadian TSB Accident Report? I have emphasised the pertinent part which refutes your assertion about the P1s understanding of the S92 and my subsequent concern over your inflammatory comment about (I assume) Nick Lappos.
So to say that because the issue was finally, after several years of confusion, put to bed on this forum, therefore there can have been no confusion elsewhere, is a leap of faith too far. Last time I looked PPruNE is not mandatory reading for all pilots!
Anyway, way off topic again, and all done to death before.
DB,
In response to 500guy's accidents stats, you looks like you imply that the 5 serious and 2 dead linesman is an outrageous amount. This is over 35 years in one specific part of utility operation. Now, how many offshore deaths is it in the same period may I ask? And how many is in twin's? And how many did the pilot just c..k up? 35 years would amount to at least a 3 digit number
Obviously, 500's post only took the stats from one specific type of aerial work, and utility work as an overall may not be the same. However, the majority of the accidents happens in bad weather, flying into various obstacles in perfectly running machines..(a very different story) and NOT from engine failures in the h/v curve.
TC,
Not knowing the difference of
and practise EOL's (engine stopped or not) is quite shocking, coming from a self-proclaimed helicopter-god like you.
You can try to sum up the amount of hours hovered in the h/v curve in that line of business over a period of 35 years, and then 2 persons have lost their life and 5 have sustained ''serious injuries'' like a broken wrist..... 
Same can be said about the conception that the h/v curve is part of the Limitations section. As the FM goes, it's only the limitations which is defined by law, the others are guides. ie. you can read out from the performance section your theoretical AUW OGE, but if you're able to lift off with more due to wind etc. that is what you work with in real life.
500,
Yeah, would be a bit more challenging with a 500ft line
BTW, it seems evident that TC don't have a concept of what aerial work is.
DB and TC,
If you think we are whazzing about in the h/v curve for the fun of it, it shows us that you don't have respect for the work we do. We all limit the time we are operating in there, and for every flight not requiring me to enter the h/v curve, I will avoid it. As said several time before, it is NOT a limitation.
Your argument would be like saying that operations down-wind is illegal as well... Not recommended, but legal either way.
In response to 500guy's accidents stats, you looks like you imply that the 5 serious and 2 dead linesman is an outrageous amount. This is over 35 years in one specific part of utility operation. Now, how many offshore deaths is it in the same period may I ask? And how many is in twin's? And how many did the pilot just c..k up? 35 years would amount to at least a 3 digit number
Obviously, 500's post only took the stats from one specific type of aerial work, and utility work as an overall may not be the same. However, the majority of the accidents happens in bad weather, flying into various obstacles in perfectly running machines..(a very different story) and NOT from engine failures in the h/v curve.
TC,
Not knowing the difference of
hundreds of real engine failures in singles
well tried fact of life that hovering inside the H/V curve ends in tears.....as it did with your previous post statistics.
Same can be said about the conception that the h/v curve is part of the Limitations section. As the FM goes, it's only the limitations which is defined by law, the others are guides. ie. you can read out from the performance section your theoretical AUW OGE, but if you're able to lift off with more due to wind etc. that is what you work with in real life.
500,
I'd like to see you install markerballs while staying out of the HV curve
BTW, it seems evident that TC don't have a concept of what aerial work is. DB and TC,
If you think we are whazzing about in the h/v curve for the fun of it, it shows us that you don't have respect for the work we do. We all limit the time we are operating in there, and for every flight not requiring me to enter the h/v curve, I will avoid it. As said several time before, it is NOT a limitation.
Your argument would be like saying that operations down-wind is illegal as well... Not recommended, but legal either way.
Peter: good morning to you in sunny California.
If I might re-iterate a couple of points to further clarify some misunderstandings:
You said:
.
I have an admission to make. In all my years of flying (30+), I have probably spent 90% in the presence of military pilots. Both inside the mil and outside the mil (ex mil pilots). Occasionally I have flown with civilian (what we call "self improver") pilots and given the opportunity, changed their way of thinking about the controls in general.
We (and the convertees) were taught to keep our hands on the controls as much as possible and never be too far away from the collective. But I do understand the impracticalities of keeping your hand on the collective always.
Now: the main issue: "aft" cyclic (to use your terms) first. Because there are several permutations where aft cyclic would never be a good idea (in any climb / in the hover / travelling downwind at low speed / close to the ground at low speed / in a dive, etc etc) one can NEVER ever make the statement: aft cyclic first and then collective. But one can ALWAYS say: collective first and then cyclic. Because of this - I stand fast with this ethos.
Finally - I am very surprised at the lack of knowledge you advertise about your fraternity over there. Shocked even, when it comes to American Instructors being unaware of dropping the Nr out of the green. Obviously a systemic failure of the training world and I now fully understand why you and others have an uphill mission! Good luck with it........
Gordy:
H/V curve...I do understand and that is why I covered my 6 by quoting BOTH the operational AND the limitations sections for the H/V curve because it depends on the operation you are conducting (private Vs public for one) and where the OEM parks the notice.
Re the necessity to hover inside the H/c this has already been discussed with 50 / 170' and myself to everyone's satisfaction, I might add. Rest assured.
Feel free to support Peter's views - are you American trained?
Double Bogey: you really do yourself no favours and certainly don't know when to give it a break - do you. How big is that chip on your shoulder. Let's move on - please, for the sake of the credibility of this forum....
If I might re-iterate a couple of points to further clarify some misunderstandings:
You said:
Note that I say "Cyclic back and collective (lever) down simultaneously, or in that order." It is simply wrong in my opinion to prioritize the collective ahead of the cyclic, especially if one's left hand is not on the collective. This would mean not moving the cyclic until the left hand could find the collective and lower it. This would be a huge mistake.
There is no harm at all in starting the cyclic back immediately to stop, not slow, the reduction of rotor rpm, which is all that lowering the lever does.
There is no harm at all in starting the cyclic back immediately to stop, not slow, the reduction of rotor rpm, which is all that lowering the lever does.
I have an admission to make. In all my years of flying (30+), I have probably spent 90% in the presence of military pilots. Both inside the mil and outside the mil (ex mil pilots). Occasionally I have flown with civilian (what we call "self improver") pilots and given the opportunity, changed their way of thinking about the controls in general.
We (and the convertees) were taught to keep our hands on the controls as much as possible and never be too far away from the collective. But I do understand the impracticalities of keeping your hand on the collective always.
Now: the main issue: "aft" cyclic (to use your terms) first. Because there are several permutations where aft cyclic would never be a good idea (in any climb / in the hover / travelling downwind at low speed / close to the ground at low speed / in a dive, etc etc) one can NEVER ever make the statement: aft cyclic first and then collective. But one can ALWAYS say: collective first and then cyclic. Because of this - I stand fast with this ethos.
Finally - I am very surprised at the lack of knowledge you advertise about your fraternity over there. Shocked even, when it comes to American Instructors being unaware of dropping the Nr out of the green. Obviously a systemic failure of the training world and I now fully understand why you and others have an uphill mission! Good luck with it........
Gordy:
H/V curve...I do understand and that is why I covered my 6 by quoting BOTH the operational AND the limitations sections for the H/V curve because it depends on the operation you are conducting (private Vs public for one) and where the OEM parks the notice.
Re the necessity to hover inside the H/c this has already been discussed with 50 / 170' and myself to everyone's satisfaction, I might add. Rest assured.
Feel free to support Peter's views - are you American trained?
Double Bogey: you really do yourself no favours and certainly don't know when to give it a break - do you. How big is that chip on your shoulder. Let's move on - please, for the sake of the credibility of this forum....
Nubian: are you on drugs or something??? Where is all this vitreol from. Calm down sunny.
What on earth are you on about re: hundreds of real engine failures Vs practice EOL's???? What? Non comprende.
H/V curve: For your information, communication between 500guy and 170' and myself resulted in a very amicable understanding of both our issues - read the f***g posts before transmitting.
My observation was that ALL those people injured/killed and all those cabs damaged will almost certainly NOT have happened OUTSIDE the damn H/v curve. It is BECAUSE you work inside the curve that these 2 dead people and 5 serious has happened - DUH!
Of course I dont have any concept of aerial work, I have never done it !!!
Please dont tarnish your industry with posts like this. Most professional helicopter pilots are top of their game, they also normally display elements of reasoning and competence outside their fundamental trade.....I simply can't believe you fall into this category after such a crass outburst....Calm down
What on earth are you on about re: hundreds of real engine failures Vs practice EOL's???? What? Non comprende.
H/V curve: For your information, communication between 500guy and 170' and myself resulted in a very amicable understanding of both our issues - read the f***g posts before transmitting.
My observation was that ALL those people injured/killed and all those cabs damaged will almost certainly NOT have happened OUTSIDE the damn H/v curve. It is BECAUSE you work inside the curve that these 2 dead people and 5 serious has happened - DUH!
Of course I dont have any concept of aerial work, I have never done it !!!
Please dont tarnish your industry with posts like this. Most professional helicopter pilots are top of their game, they also normally display elements of reasoning and competence outside their fundamental trade.....I simply can't believe you fall into this category after such a crass outburst....Calm down
Join Date: Nov 2008
Location: UK
Age: 66
Posts: 919
Likes: 0
Received 0 Likes
on
0 Posts
Critical point rpm in auto rotation
If you wish to improve your chances and extend the critical rpm to a lower figure, enquire to the manufacturer if you can increase the lower pitch travel to zero degrees or even a negative setting.
I have frequently practised auto rotation techniques with drones, allowing the pitch to stay on with a power cut in a high hover, watched as the main rotor blades stall in flight, nearly stop, then bottom the lever to a negative pitch setting and observed as the RRPM recovered. (with negative pitch, the angle of attack is less).
The only down side of this set up is often bottom lever is then too much (down)for normal approaches, so you have to be mindful of controlling the amount of down lever movement, as you do with cyclic.
Could be a safety enhancement to help recover rpm when normally it would not be recoverable.
I have frequently practised auto rotation techniques with drones, allowing the pitch to stay on with a power cut in a high hover, watched as the main rotor blades stall in flight, nearly stop, then bottom the lever to a negative pitch setting and observed as the RRPM recovered. (with negative pitch, the angle of attack is less).
The only down side of this set up is often bottom lever is then too much (down)for normal approaches, so you have to be mindful of controlling the amount of down lever movement, as you do with cyclic.
Could be a safety enhancement to help recover rpm when normally it would not be recoverable.
Join Date: Dec 2006
Location: UK and MALTA
Age: 61
Posts: 1,297
Likes: 0
Received 18 Likes
on
4 Posts
Nubian - I read your post and it is compelling reading. At first glance 500 Guys posted stats look horrendous but as you say, caompared to other sectors they seem remarkable benign. Thanks for pointing this out.
Please do not think I do not respect the work 500guy does. It is the hand skilled kind of flying we, in our fully automated heavy helicopters have long since stopped dreaming about.
It is bizzarre though when you re-read 500guys post...it sort of says "Hey look how safe we are....we have only killed a few people and maimed a few more". Of course in hindsight, in the light of your explanation, it makes more sense.
DB
Please do not think I do not respect the work 500guy does. It is the hand skilled kind of flying we, in our fully automated heavy helicopters have long since stopped dreaming about.
It is bizzarre though when you re-read 500guys post...it sort of says "Hey look how safe we are....we have only killed a few people and maimed a few more". Of course in hindsight, in the light of your explanation, it makes more sense.
DB
DB and HC,
Time to be honest here folks.
You two were the 225 side of the 92/225 argument here at Rotor Heads.
Nick Lappos was on the other side.
As documented by the TSB and quoted by John Eacott.....he posted here under his own name. You two did not...have not....and I assume will not.
You two safely hide your connection to the 225 program while Nick did just the opposite.
You attacked him and continue to attack him, HC much less so than DB, in defiance of the ROE's here particularly in DB's case, and reject the findings of a very detailed investigation and a very frank honest evaluation of all the evidence, testimony, and forensic examination of the factors that led up to that crash.
Bluntly, you two are pushing a MYTH and refuse to accept the findings of the TSB.
That needs to stop.
DB....you need to withdraw that comment that Eacott quoted.....and offer an apology to Nick and the rest of us. Plainly, many of us see it this way or you would not have gotten those PM's you mentioned.
I guess you cannot figure out that a PM is usually a polite way of telling you that you are wrong and giving you a chance to make things right before being called out in public by someone.
I find the quoted comment utterly offensive and a direct violation of the ROE here. Be the Gentleman and do the right thing.....remove it...and apologize.
Time to be honest here folks.
You two were the 225 side of the 92/225 argument here at Rotor Heads.
Nick Lappos was on the other side.
As documented by the TSB and quoted by John Eacott.....he posted here under his own name. You two did not...have not....and I assume will not.
You two safely hide your connection to the 225 program while Nick did just the opposite.
You attacked him and continue to attack him, HC much less so than DB, in defiance of the ROE's here particularly in DB's case, and reject the findings of a very detailed investigation and a very frank honest evaluation of all the evidence, testimony, and forensic examination of the factors that led up to that crash.
Bluntly, you two are pushing a MYTH and refuse to accept the findings of the TSB.
That needs to stop.
DB....you need to withdraw that comment that Eacott quoted.....and offer an apology to Nick and the rest of us. Plainly, many of us see it this way or you would not have gotten those PM's you mentioned.
I guess you cannot figure out that a PM is usually a polite way of telling you that you are wrong and giving you a chance to make things right before being called out in public by someone.
I find the quoted comment utterly offensive and a direct violation of the ROE here. Be the Gentleman and do the right thing.....remove it...and apologize.
3.0 Conclusions
3.1 Findings as to Causes and Contributing Factors
Galling on a titanium attachment stud holding the filter bowl assembly to the main gearbox (MGB) prevented the correct preload from being applied during installation. This condition was exacerbated by the number of oil filter replacements and the re-use of the original nuts.
Titanium alloy oil filter bowl mounting studs had been used successfully in previous Sikorsky helicopter designs; in the S-92A, however, the number of unexpected oil filter changes resulted in excessive galling.
Reduced preload led to an increase of the cyclic load experienced by one of the titanium MGB oil filter bowl assembly attachment studs during operation of CHI91, and to fatigue cracking of the stud, which then developed in a second stud due to increased loading resulting from the initial stud failure. The two studs broke in cruise flight resulting in a sudden loss of oil in the MGB.
Following the Australian occurrence, Sikorsky and the Federal Aviation Administration (FAA) relied on new maintenance procedures to mitigate the risk of failure of damaged mounting studs on the MGB filter bowl assembly and did not require their immediate replacement.
Cougar Helicopters did not effectively implement the mandatory maintenance procedures in Aircraft Maintenance Manual (AMM) Revision 13 and, therefore, damaged studs on the filter bowl assembly were not detected or replaced.
Ten minutes after the red MGB OIL PRES warning, the loss of lubricant caused a catastrophic failure of the tail take-off pinion, which resulted in the loss of drive to the tail rotor shafts.
The S-92A rotorcraft flight manual (RFM) MGB oil system failure procedure was ambiguous and lacked clearly defined symptoms of either a massive loss of MGB oil or a single MGB oil pump failure. This ambiguity contributed to the flight crew's misdiagnosis that a faulty oil pump or sensor was the source of the problem.
The pilots misdiagnosed the emergency due to a lack of understanding of the MGB oil system and an over-reliance on prevalent expectations that a loss of oil would result in an increase in oil temperature. This led the pilots to incorrectly rely on MGB oil temperature as a secondary indication of an impending MGB failure.
By the time that the crew of CHI91 had established that MGB oil pressure of less than 5 psi warranted a "land immediately" condition, the captain had dismissed ditching in the absence of other compelling indications such as unusual noises or vibrations.
The captain's decision to carry out pilot flying (PF) duties, as well as several pilot not flying (PNF) duties, resulted in excessive workload levels that delayed checklist completion and prevented the captain from recognizing critical cues available to him.
The pilots had been taught during initial and recurrent S-92A simulator training that a gearbox failure would be gradual and always preceded by noise and vibration. This likely contributed to the captain's decision to continue towards CYYT.
Rather than continuing with the descent and ditching as per the RFM, the helicopter was levelled off at 800 feet asl, using a higher power setting and airspeed than required. This likely accelerated the loss of drive to the tail rotor and significantly reduced the probability of a successful, controlled ditching.
The lack of recent, modern, crew resource management (CRM) training likely contributed to the communication and decision-making breakdowns which led to the selection of an unsafe flight profile.
The throttles were shut off prior to lowering the collective, in response to the loss of tail rotor thrust. This caused significant main rotor rpm droop.
The pilots experienced difficulties controlling the helicopter following the engine shut-down, placing the helicopter in a downwind autorotative descent with main rotor rpm and airspeed well below prescribed RFM limits. This led to an excessive rate of descent from which the pilots could not recover prior to impact.
The severity of the impact likely rendered some passengers unconscious. The other occupants seated in the helicopter likely remained conscious for a short period of time, but became incapacitated due to the impact and cold water shock, and lost their breath hold ability before they could escape the rapidly sinking helicopter.
3.1 Findings as to Causes and Contributing Factors
Galling on a titanium attachment stud holding the filter bowl assembly to the main gearbox (MGB) prevented the correct preload from being applied during installation. This condition was exacerbated by the number of oil filter replacements and the re-use of the original nuts.
Titanium alloy oil filter bowl mounting studs had been used successfully in previous Sikorsky helicopter designs; in the S-92A, however, the number of unexpected oil filter changes resulted in excessive galling.
Reduced preload led to an increase of the cyclic load experienced by one of the titanium MGB oil filter bowl assembly attachment studs during operation of CHI91, and to fatigue cracking of the stud, which then developed in a second stud due to increased loading resulting from the initial stud failure. The two studs broke in cruise flight resulting in a sudden loss of oil in the MGB.
Following the Australian occurrence, Sikorsky and the Federal Aviation Administration (FAA) relied on new maintenance procedures to mitigate the risk of failure of damaged mounting studs on the MGB filter bowl assembly and did not require their immediate replacement.
Cougar Helicopters did not effectively implement the mandatory maintenance procedures in Aircraft Maintenance Manual (AMM) Revision 13 and, therefore, damaged studs on the filter bowl assembly were not detected or replaced.
Ten minutes after the red MGB OIL PRES warning, the loss of lubricant caused a catastrophic failure of the tail take-off pinion, which resulted in the loss of drive to the tail rotor shafts.
The S-92A rotorcraft flight manual (RFM) MGB oil system failure procedure was ambiguous and lacked clearly defined symptoms of either a massive loss of MGB oil or a single MGB oil pump failure. This ambiguity contributed to the flight crew's misdiagnosis that a faulty oil pump or sensor was the source of the problem.
The pilots misdiagnosed the emergency due to a lack of understanding of the MGB oil system and an over-reliance on prevalent expectations that a loss of oil would result in an increase in oil temperature. This led the pilots to incorrectly rely on MGB oil temperature as a secondary indication of an impending MGB failure.
By the time that the crew of CHI91 had established that MGB oil pressure of less than 5 psi warranted a "land immediately" condition, the captain had dismissed ditching in the absence of other compelling indications such as unusual noises or vibrations.
The captain's decision to carry out pilot flying (PF) duties, as well as several pilot not flying (PNF) duties, resulted in excessive workload levels that delayed checklist completion and prevented the captain from recognizing critical cues available to him.
The pilots had been taught during initial and recurrent S-92A simulator training that a gearbox failure would be gradual and always preceded by noise and vibration. This likely contributed to the captain's decision to continue towards CYYT.
Rather than continuing with the descent and ditching as per the RFM, the helicopter was levelled off at 800 feet asl, using a higher power setting and airspeed than required. This likely accelerated the loss of drive to the tail rotor and significantly reduced the probability of a successful, controlled ditching.
The lack of recent, modern, crew resource management (CRM) training likely contributed to the communication and decision-making breakdowns which led to the selection of an unsafe flight profile.
The throttles were shut off prior to lowering the collective, in response to the loss of tail rotor thrust. This caused significant main rotor rpm droop.
The pilots experienced difficulties controlling the helicopter following the engine shut-down, placing the helicopter in a downwind autorotative descent with main rotor rpm and airspeed well below prescribed RFM limits. This led to an excessive rate of descent from which the pilots could not recover prior to impact.
The severity of the impact likely rendered some passengers unconscious. The other occupants seated in the helicopter likely remained conscious for a short period of time, but became incapacitated due to the impact and cold water shock, and lost their breath hold ability before they could escape the rapidly sinking helicopter.
Last edited by SASless; 17th Dec 2013 at 11:42.
Join Date: Dec 2006
Location: UK and MALTA
Age: 61
Posts: 1,297
Likes: 0
Received 18 Likes
on
4 Posts
"The pilots had been taught during initial and recurrent S-92A simulator training that a gearbox failure would be gradual and always preceded by noise and vibration. This likely contributed to the captain's decision to continue towards CYYT."
The pilots experienced difficulties controlling the helicopter following the engine shut-down, placing the helicopter in a downwind autorotative descent with main rotor rpm and airspeed well below prescribed RFM limits. This led to an excessive rate of descent from which the pilots could not recover prior to impact.
My point is that "the above" is the kind of inappropriate information that can directly lead to crews making mistakes. Stressing that in the case of S92 the investigators have only noted this was likely to have contributed. This is not about the S92. The old girl would have served the crew well no doubt had the crew been inclined to follow the procedures, but as your post suggest, even these were ambigous in this case.
SAS - CALLING FOR ME TO APOLOGISE
I will not apologise for implying that misleading pilots into the belief that the RPM can readily decay beyond the RFM limits is acceptable especially since this post was lodged in direct contradiction to the sound advice offered by Peter. I note that in doing so (see above) the horrible subject of decayed Nr and low airspeed seems to have eventually caused the loss of the crew and PAX in the S92. I wonder if that poor crew had had the benefit in hindsight of Peter's post whether they may have been able to fare better. Who knows.
I will apologise to all, including Nick and JD if any of you inferred from my posts that the misinformation stated above that you SAS posted kindly for us, had anything to do with them.
SAS the detail you have posted above serves only to remind us of the folly of listening too, being subjected to and following inappropriate advice and guidance especially when it is beyond the limits cleary stated in the flight manual. The limits in the flight manual are provided by the likes of Nick and JD, at significant personal risk to them, to keep us all safe. My respect for them and the work they do is implicit in my continued stated belief that we should follow the flight manual. That is my tribute to them!!
For John Eacott, thank you for recognising that I am capable of an apology when I am wrong. It does not happen often (being wrong) and hurts a bit so it took a bit of time to get back to you.
To SP - I hope now you can see the relevance of my posts and that my intent was not to link the TPs to the incident. It was the pirnciple of inappropriate information beyond the limits of the RFM.
To TC - now I know how it feels to be you!
DB
Last edited by DOUBLE BOGEY; 17th Dec 2013 at 13:11.
