Sikorsky S-92: From Design to Operations
Where do these "Vibrations" eminate from that are said to be so bad on the 92 ?
Join Date: Feb 2005
Location: ****
Posts: 279
Likes: 0
Received 0 Likes
on
0 Posts
Exactly, so my point is if your machine is set up properly then, in my experience ,the vibration in the S92 is no worse than any other aircraft, infact I find it a more pleasant experience than the 225.
NST
NST
Join Date: Feb 2007
Location: all over?
Posts: 250
Likes: 0
Received 0 Likes
on
0 Posts
New checks and procedures are hardly a substitute for a decent MRGB! The new checklist will be great at telling you your time is up and you really should be on the ground.
Revised servicing procedures and inspections are great if you know exactly what caused the bolts to fail.
There is an answer to the S-92's weakness - fit an ELS and then do something about the vibration.
Revised servicing procedures and inspections are great if you know exactly what caused the bolts to fail.
There is an answer to the S-92's weakness - fit an ELS and then do something about the vibration.
Whilst I agree that there have been weaknesses in the 92 MRGB, a whole series of mods over the last year or so (most detailed already on here), have greatly improved the reliability and addressed many of the previous weaknesses. I am not in the game of singing praises for the sake of it, but lets keep this a sensible and balanced informed debate.
Yes the new checklist will tell you to get on the ground/water, and that is bloody important when it comes to surviving. It is what should have happened in the Cougar accident. For those of us operating it, recent amendments have also greatly improved the fault diagnosis, enabling us to better locate the root cause of the pressure loss, and if possible, the procedure for safely keeping the machine in the air. IMO this was a very important revision to the checklist, and IIRC came about after the Shell Brunei incident. So - no, not a substitute, but I think if you were involved with this aircraft you would perhaps see that great improvements are being made to the MRGB in COMBINATION with procedural, checklist and maintenance procedures, and comments such as those from Crab, are both uninformed and counterproductive to the overall debate.
Join Date: Oct 2004
Location: By a river
Posts: 186
Likes: 0
Received 0 Likes
on
0 Posts
Horror Box;
You keep stating all of these great improvements which have helped the situation, but you continually fail to list them as per the request from maxwelg2. So, why not provide us with a specific list of operational and maintenance changes which you claim to have followed closely.
I am sure the pax are greatly relieved to hear from the S92 pilots and their faith in the aircraft but this is what we have done far too long in this business, treat them like cattle, load em up, close the doors and bs them when anything happens.
But these offshore workers are a bit different than the normal cattle loaded onto the airlines as their travel is intimately related to their work, their specific training required to fly offshore attests to that.
I have read all of the 125 Q&As between the offshore workers and Cougar and the Cougar responses seem to speak down to the questioners. I understand that to a degree the pax are not intimately familiar with every aspect of aviation, but in the case of offshore travel, the degree of risk involved and the two recent losses, I think we have to find a new way to make the pax more inclusive. As stated before, they are the reason the helicopters are required and we owe them much more than a simple, "I fly it, so you don't have to worry". They are not buying this anymore and I don't blame them, they deserve better than that.
carholme
You keep stating all of these great improvements which have helped the situation, but you continually fail to list them as per the request from maxwelg2. So, why not provide us with a specific list of operational and maintenance changes which you claim to have followed closely.
I am sure the pax are greatly relieved to hear from the S92 pilots and their faith in the aircraft but this is what we have done far too long in this business, treat them like cattle, load em up, close the doors and bs them when anything happens.
But these offshore workers are a bit different than the normal cattle loaded onto the airlines as their travel is intimately related to their work, their specific training required to fly offshore attests to that.
I have read all of the 125 Q&As between the offshore workers and Cougar and the Cougar responses seem to speak down to the questioners. I understand that to a degree the pax are not intimately familiar with every aspect of aviation, but in the case of offshore travel, the degree of risk involved and the two recent losses, I think we have to find a new way to make the pax more inclusive. As stated before, they are the reason the helicopters are required and we owe them much more than a simple, "I fly it, so you don't have to worry". They are not buying this anymore and I don't blame them, they deserve better than that.
carholme
Join Date: Mar 2009
Location: Canada
Posts: 55
Likes: 0
Received 0 Likes
on
0 Posts
Horror box, with all due respect, I think you're both right - your post details some issues already addressed, and Crab's details some still on the "to do" list ?
Your concern about the redundancy of the redundancy is certainly important but wouldn't it's benefits outweigh it's risks ? (not to mention PR, and, if they came up with an ELS with say 60 minutes instead of 30, a real win-win situation ?)
Your concern about the redundancy of the redundancy is certainly important but wouldn't it's benefits outweigh it's risks ? (not to mention PR, and, if they came up with an ELS with say 60 minutes instead of 30, a real win-win situation ?)
Horrorbox - exactly which of the new checklists, procedures or modifications will help a crew at 8000' in the cruise when the filter bowl studs fail????
All the peripheral tinkering hasn't addressed the basic weakness of the MRGB - there is no run-dry or ELS. At least when a Sea King ELS fails you know you have 5 mins to get it on the ground/water and, other than having a big hole in the gearbox as well as an ELS malfunction (now we are talking multiple failures rather than single point like the S-92), there is a less than remote chance of you ending up in that situation.
PS the Sea King is 50 years old and the S-92 is brand new and (allegedy) super-safe.
All the peripheral tinkering hasn't addressed the basic weakness of the MRGB - there is no run-dry or ELS. At least when a Sea King ELS fails you know you have 5 mins to get it on the ground/water and, other than having a big hole in the gearbox as well as an ELS malfunction (now we are talking multiple failures rather than single point like the S-92), there is a less than remote chance of you ending up in that situation.
PS the Sea King is 50 years old and the S-92 is brand new and (allegedy) super-safe.
Join Date: Dec 2008
Location: ASIA
Posts: 7
Likes: 0
Received 0 Likes
on
0 Posts
today one of saudi MOI s-92 had INPUT CHIP caution the cew experienced Unusual vibrations and noise after take off at 3000ft (1000 ft) AGL then thy descend for landing and at about 300 ft AGL the caution illuminated the aircraft and the crew landed Safely
Join Date: Mar 2009
Location: St. John's, Newfoundland
Age: 54
Posts: 178
Received 0 Likes
on
0 Posts
Exactly, so my point is if your machine is set up properly then, in my experience ,the vibration in the S92 is no worse than any other aircraft, infact I find it a more pleasant experience than the 225.
I recall earlier posts on this thread commenting on the S-92a vibration issues, mostly blamed on helo weight and 4-rotor design. There have been other good points raised recently such as the use of the aux fuel tanks, payload, flying at max. altitude to improve fuel efficiency etc. over here in NL.
Are we pushing this helo past its design without even realizing it?
Is there any conclusions from HUMS data wrt. variance potential in S-92a vibration levels with AVS on/off, full payload, aux tanks in/out?
When will the TSB release a preliminary report on the stud failure mode?
I suppose being a technical guy I'm looking for a technical explanation and solution. Everything is fixable given the right tools/resources.
Max
Yes the new checklist will tell you to get on the ground/water, and that is bloody important when it comes to surviving. It is what should have happened in the Cougar accident
Join Date: Mar 2009
Location: St. John's, Newfoundland
Age: 54
Posts: 178
Received 0 Likes
on
0 Posts
From the passenger's point of view there is not much to choose between them - you can either have the slightly larger-cabined but vibratory 92 or the slightly smaller but smoother 225. But I know that the Norwegian offshore wokers unions have repeatedly complained about vibration levels on the 92 - I suspect they would prefer the 225 if they tried it.
Now that I am officially out of the rotorcraft industry, I can finally post on the “vibration issues” with the S-92. In my former position I had the opportunity to go around the world to help customers put the S-92 in service. During that time, I have had the opportunity to ride on customer 92s in the Gulf, the North Sea and Newfoundland. Barring some maintenance issues, all of the 92s I have flown on have been within limits. And there in lies the problem. While the limits on the 92 are acceptable on a military aircraft they are not acceptable in the civil market. It is my experience that some of the operators do just enough track and balance work to get the ship within limits. If you want to feel what a well tuned 92 feels like you need to take a trip to Newfoundland. Their 92 is the smoothest customer aircraft that I have flown in. A well tuned 92 is every bit as good as a Super Puma (which I have also had the opportunity to fly in.)
Road Warrior
Now that I am officially out of the rotorcraft industry, I can finally post on the “vibration issues” with the S-92. In my former position I had the opportunity to go around the world to help customers put the S-92 in service. During that time, I have had the opportunity to ride on customer 92s in the Gulf, the North Sea and Newfoundland. Barring some maintenance issues, all of the 92s I have flown on have been within limits. And there in lies the problem. While the limits on the 92 are acceptable on a military aircraft they are not acceptable in the civil market. It is my experience that some of the operators do just enough track and balance work to get the ship within limits. If you want to feel what a well tuned 92 feels like you need to take a trip to Newfoundland. Their 92 is the smoothest customer aircraft that I have flown in. A well tuned 92 is every bit as good as a Super Puma (which I have also had the opportunity to fly in.)
Road Warrior
Road warrior, hope you're still reading these posts, I have a question that hopefully you can answer. I stopped at your post as my eyes were glazing over trying to go back through all the history, plus you made a very important comparison to numerous S-92s that you'd flown in globally. For those interested, see posts 207, 221, 473 and trawl through after 612 for more applicable posts.
Does the S-92a AVS automatically compensate for variable payload, weight distribution in the passenger cabin, or does it have to be manually tuned? Could this explain the differing feedback on vibration levels noticed? I'm thinking along the lines of maximum payload + uneven weight distribution in the cabin = quiescent imbalance on airframe. Correct me if I'm way off base (no pun intended) and the ratio of PAX and fuel/cargo combined payload is insignificant in comparison to total aircraft weight.
I'm curious now as thinking back over the last 4 years of S-92 flying I can recall days when the vibes were worse, just wondering why the difference when all the a/c are assumed to be well tuned and knowing that Cougar would have been doing the highest maintenance standard, making it seem more odd that a variable vibration issue should be present. Or is it all down to how hard the rotors are working and all the variables in play there?
Ah well, back to trawling through the posts whilst waiting for some hopefully beneficial insight...
Max,
the system does not automatically compensate for anything, once tuned. The force generators are units containing dual eccentrically rotating masses, which by altering the phase will generate a force in a particular axis and frequency.
The perceived vibration will vary as a function of payload and the relative mass of fuel and load is significant - together they represent a 1/3 of the total max weight, so 50% of the empty weight. Generally, heavily loaded aircraft have greater fuselage damping, so will feel smoother.
I don't believe this argument is relevant to anything relating to the MRGB.
the system does not automatically compensate for anything, once tuned. The force generators are units containing dual eccentrically rotating masses, which by altering the phase will generate a force in a particular axis and frequency.
The perceived vibration will vary as a function of payload and the relative mass of fuel and load is significant - together they represent a 1/3 of the total max weight, so 50% of the empty weight. Generally, heavily loaded aircraft have greater fuselage damping, so will feel smoother.
I don't believe this argument is relevant to anything relating to the MRGB.
Join Date: Mar 2009
Location: St. John's, Newfoundland
Age: 54
Posts: 178
Received 0 Likes
on
0 Posts
212man, I hear you and would like to be convinced that the way the S-92s have been operated over here has not contributed to the stud failures. Would a detailed examination of various sources of S-92 HUMS data not give us a feel for common/abnormal inherent vibration issues at the MGB? Just wondering when we're going to find out the root cause failure mode for the titanium studs so that we can move forward with confidence that the replacement steel studs cannot suffer from the same fate. I'm assuming that there is now increased maintenance/inspection frequency on these studs, perhaps even change out of the studs every time the filter housing is removed. Can Horror box or someone else in the maintenance crews confirm this?
Max
Max
Join Date: Sep 2008
Location: SW Asia
Posts: 82
Likes: 0
Received 0 Likes
on
0 Posts
max,
Your religious belief in HUMS as omniscient and all-knowing is comforting, but totally misplaced. So too is your belief that "the way it is operated" somehow makes studs break or not.
Please, I would bet you are very good at something (I earnestly believe everyone is good at something). Please tell us what that is, and stick to that.
It is almost pathetic to see you appeal to anonymous posters on a rumor web site for assurances. I understand how you feel, but cannot for the life of me understand how you are attempting to put your fears aside using the (sometimes) inane posts of strangers who (like me) do not even believe themselves enough to post with their real names.....
Your religious belief in HUMS as omniscient and all-knowing is comforting, but totally misplaced. So too is your belief that "the way it is operated" somehow makes studs break or not.
Please, I would bet you are very good at something (I earnestly believe everyone is good at something). Please tell us what that is, and stick to that.
It is almost pathetic to see you appeal to anonymous posters on a rumor web site for assurances. I understand how you feel, but cannot for the life of me understand how you are attempting to put your fears aside using the (sometimes) inane posts of strangers who (like me) do not even believe themselves enough to post with their real names.....
Ramen - the way a helicopter is operated (MAUM, High IAS, High DA, lots of manoeuvering etc) has everything to do with the fatigue spectrum.
The only question really is whether the vibration caused by the rotor in the S-92 has contributed to failure of the filter studs - if so then the way the aircraft is operated may be very pertinent indeed.
The only question really is whether the vibration caused by the rotor in the S-92 has contributed to failure of the filter studs - if so then the way the aircraft is operated may be very pertinent indeed.
Join Date: Sep 2008
Location: SW Asia
Posts: 82
Likes: 0
Received 0 Likes
on
0 Posts
crab, you are certainly right in the very general case, but that is such a broad statement in this case it is worthless in this specific case. An oil operator carrying passengers to a rig cannot operate so poorly that it could affect the basic fatigue life, especially in a modern aircraft. The S92 has only 7 parts that have any fatigue life.
It is a disservice to put in the minds of the unwashed, like max, who is seeking answers, the notion that the way a operator flies could make bolts break. They are not mustering cattle in the bush with a one pilot operation! There are other pilots, HUMS. passengers and such to help monitor.
It is a disservice to put in the minds of the unwashed, like max, who is seeking answers, the notion that the way a operator flies could make bolts break. They are not mustering cattle in the bush with a one pilot operation! There are other pilots, HUMS. passengers and such to help monitor.
Join Date: Mar 2009
Location: Far far away
Posts: 41
Likes: 0
Received 0 Likes
on
0 Posts
Noodles:
You are a very self confident person aren't you? In this case you don't know what you are talking about. The company I worked for operated the 92 at a slower cruise IAS than our competitor, and they had a lot more cracks in the airframe structure than we had and have. The reasonfor the higher IAS (Sikorsky figures) was that their contract with the oil company dictated a shorter sector time than we wanted to offer (shorter flight time, lower costs), so they won the contract. How is that for safety concerns in the business??
Anyway - don't put people down when they have legitimate concerns of the machine they are forced to sit in.
I have been in the offshore business for more than 30 years and I understand Max very well.
I have also been a test-pilot for almost the same number of years too, working closely with Part M people so don’t tell me vibration is not a factor in airframe (and possible other components) fatigue life, regardless what the OEM's say.
I am not suggesting that the oil filter studs broke because of vibration, but let people express their concerns without hitting them on their head.
An oil operator carrying passengers to a rig cannot operate so poorly that it could affect the basic fatigue life, especially in a modern aircraft. The S92 has only 7 parts that have any fatigue life.
You are a very self confident person aren't you? In this case you don't know what you are talking about. The company I worked for operated the 92 at a slower cruise IAS than our competitor, and they had a lot more cracks in the airframe structure than we had and have. The reasonfor the higher IAS (Sikorsky figures) was that their contract with the oil company dictated a shorter sector time than we wanted to offer (shorter flight time, lower costs), so they won the contract. How is that for safety concerns in the business??
Anyway - don't put people down when they have legitimate concerns of the machine they are forced to sit in.
I have been in the offshore business for more than 30 years and I understand Max very well.
I have also been a test-pilot for almost the same number of years too, working closely with Part M people so don’t tell me vibration is not a factor in airframe (and possible other components) fatigue life, regardless what the OEM's say.
I am not suggesting that the oil filter studs broke because of vibration, but let people express their concerns without hitting them on their head.
Join Date: Mar 2009
Location: St. John's, Newfoundland
Age: 54
Posts: 178
Received 0 Likes
on
0 Posts
Ramen noodles
I have nothing to hide, have you? My work name is Max, speak to anyone over here and they'll tell you all about me. I am a metering/measurement consultant, who specializes in state of the art database and instrumentation that measure various fluid and gas production/flows to a high level of confidence and accuracy. If you read though my earlier posts you'll get to know me a whole lot better...
I am also originally from the nuclear power industry and have extensive electrical and electronic engineering qualifications/experience. I am also a time-served craftsman (instruments).
I am not a pilot/avionics engineer, but have been in the offshore industry since '91 and have many flying hours experience as a PAX. So does that classify me as unwashed in the experiences of helo flying? Please clarify your definition of unwashed...
Wrt. HUMS I do not worship the system, but see it as a diagnostic tool that requires extensive experience to fully comprehend. Hopefully one day a neural network system will simplify and improve its analytical and condition-based monitoring potential.
I do not believe that you fully understand how I feel as I'm assuming that you're qualified and work in a different branch of this industry from me. The only commonality we may have is using helos as a mode of transport.
I'm not attempting to allay fears, I'm just trying to understand the collective view of this helo from multiple opinions. I'll make my own judgement on what to believe from this forum, thank you very much.
Anyway, back to the constructive posts. L2driver, glad to hear you understand us PAX along with other posters such as carholme, 212man, to name just a few recent contributors to this post.
Still waiting to hear from Horror Box what has been changed, is maximum IAS one of the modified parameters in the RFM? If you like please PM me.
Rest assured, I've got a list of questions that I'll personally be putting forward to the oil company HSEQ advisors, and if I don't get acceptable answers I'll go straight to Cougar. I'm still hoping that the pending TSB report will provide clarification to some of my questions, but may be a long way away.
This may officially be a rumour network, but in reality contains a wealth of knowledge and experience that IMO is invaluable.
I have nothing to hide, have you? My work name is Max, speak to anyone over here and they'll tell you all about me. I am a metering/measurement consultant, who specializes in state of the art database and instrumentation that measure various fluid and gas production/flows to a high level of confidence and accuracy. If you read though my earlier posts you'll get to know me a whole lot better...
I am also originally from the nuclear power industry and have extensive electrical and electronic engineering qualifications/experience. I am also a time-served craftsman (instruments).
I am not a pilot/avionics engineer, but have been in the offshore industry since '91 and have many flying hours experience as a PAX. So does that classify me as unwashed in the experiences of helo flying? Please clarify your definition of unwashed...
Wrt. HUMS I do not worship the system, but see it as a diagnostic tool that requires extensive experience to fully comprehend. Hopefully one day a neural network system will simplify and improve its analytical and condition-based monitoring potential.
I do not believe that you fully understand how I feel as I'm assuming that you're qualified and work in a different branch of this industry from me. The only commonality we may have is using helos as a mode of transport.
I'm not attempting to allay fears, I'm just trying to understand the collective view of this helo from multiple opinions. I'll make my own judgement on what to believe from this forum, thank you very much.
Anyway, back to the constructive posts. L2driver, glad to hear you understand us PAX along with other posters such as carholme, 212man, to name just a few recent contributors to this post.
Still waiting to hear from Horror Box what has been changed, is maximum IAS one of the modified parameters in the RFM? If you like please PM me.
Rest assured, I've got a list of questions that I'll personally be putting forward to the oil company HSEQ advisors, and if I don't get acceptable answers I'll go straight to Cougar. I'm still hoping that the pending TSB report will provide clarification to some of my questions, but may be a long way away.
This may officially be a rumour network, but in reality contains a wealth of knowledge and experience that IMO is invaluable.
Join Date: Mar 2003
Location: the hills of halton
Age: 71
Posts: 809
Likes: 0
Received 0 Likes
on
0 Posts
Mr Noodles , if you are a pilot do you treat your passengers with such disdain ?.
Now I remember where I have seen a similar attitude , you work for Eurocopter customer support don't you.
Now I remember where I have seen a similar attitude , you work for Eurocopter customer support don't you.
The RFM hasn't changed, and always said that. Individual operators may be placing more emphasis on what land immediately actually means, perhaps?