EC225 crash near Bergen, Norway April 2016
Lastly, one change I would like to see the FAA implement is for every certified gearbox design in production to undergo a formal design review every few years using the most current analysis tools/techniques available. This analysis technology improves at a very rapid pace, and this proactive approach could likely reveal many potential problems that were missed in the original design analysis.
Getting industry buy in to a never ending cost center over and above current cert requirements puts a very hard edge on "the continuous improvement model" -- for all that I agree on periodic review to get after some of those difficult trade offs that have to be made to get anything built.
(I also suspect that any analysis short comings come more from the bean counting side than the design team side ...)
- It would be quite expensive: Who pays for it?
- It probably wouldn't have caught this one. Using the planetary gears as bearing outer races is not an immediately visible safety hazard. It becomes one since material properties of a gear and a bearing race are somewhat similar but in detail not identical. A planetary gear with a separate bearing race inside could similarly break apart, e.g. if the bearing fails. Admittedly the latter design would put one more layer between potential problem and disaster. In that way a review of the redundancy concept might indeed have caught this design as lacking one layer of redundancy.
It is a bit sad to see that both manufacturers of the two only available (competitive) Types in this Heli category used technical trickery in order to shave weight. Sikorsky used a clever paragraph in order to circumvent the necessity for a more massive MGB/Gears that would have the mass to run dry for 30 minutes. AH tried to squeeze every ounce of the MGB by using the gears as outer races and putting the lift load through a mere 3 suspension bars.
Might be the downside of the cut- throat nature of competition in the O&G industry.
SAS,
Glycol is an acceptable means to meet the regs and far superior to the 92's PowerPoint presentation promises which should never been accepted by the regulators.
The Sultan
Glycol is an acceptable means to meet the regs and far superior to the 92's PowerPoint presentation promises which should never been accepted by the regulators.
The Sultan
BG
As usual you miss the point and pay scant attention to what was posted.
My contention was "Run Dry" should be exactly that..."Dry"!
I suppose you are ignorant to the the contents of the S-92 Emergency Checklist and the Cougar Accident Report....as evidenced by your post.....or are you just trolling again?
My contention was "Run Dry" should be exactly that..."Dry"!
I suppose you are ignorant to the the contents of the S-92 Emergency Checklist and the Cougar Accident Report....as evidenced by your post.....or are you just trolling again?
@SASless
So by this You mean that the FAR29 goal of run dry is that it has to be dry, and not the ability to continue to fly safe if all MGB oil leaves the MGB ?
Then loss of one engine literally meaning it has to fall of the A/C ?
Yes, I know...the term is 'One Engine Inoperative'. But also, in FAR29(29.927) I don't think they use the term "Run Dry".
By the way, why does it matter how the manufacturer is keeping A/C able to safe continue to fly ?
My contention was "Run Dry" should be exactly that..."Dry"!
So by this You mean that the FAR29 goal of run dry is that it has to be dry, and not the ability to continue to fly safe if all MGB oil leaves the MGB ?
Then loss of one engine literally meaning it has to fall of the A/C ?
Yes, I know...the term is 'One Engine Inoperative'. But also, in FAR29(29.927) I don't think they use the term "Run Dry".
By the way, why does it matter how the manufacturer is keeping A/C able to safe continue to fly ?
Bladegrabber
The 30 minute is to give enough time to land "safely" after loss of primary lube. Secondary glycol is fine, the 429's case reservoirs that trap oil after most has bled out is better as it has been demonstrated to allow around four hours at flight powers. Run dry to my knowledge is not a requirement. It is loss of primary lube/oil due to seal/line/filter failure where the bulk of the lube is lost.
SAS, by any measure the 12 minutes a 92 can last before catastrophic failure is inadequate.
The Sultan
The 30 minute is to give enough time to land "safely" after loss of primary lube. Secondary glycol is fine, the 429's case reservoirs that trap oil after most has bled out is better as it has been demonstrated to allow around four hours at flight powers. Run dry to my knowledge is not a requirement. It is loss of primary lube/oil due to seal/line/filter failure where the bulk of the lube is lost.
SAS, by any measure the 12 minutes a 92 can last before catastrophic failure is inadequate.
The Sultan
The question is when we use these descriptions the words should accurately describe what we are talking about.
I see "Run Dry" should mean just that...."dry".
Did not Sikosky test a 92 MGB using the isolation concept and only terminated the test when the MGB had lasted longer than the max fuel endurance of the aircraft?
If a Glycol system fails to work as advertised, be it in cooling or just an indication that is working....then that machine has no "Run Dry" capability in reality.
So...if you want use some descriptive wording....or a design concept that requires coolant or trapped oil....is that a "Run Dry" Design?
I see "Run Dry" should mean just that...."dry".
Did not Sikosky test a 92 MGB using the isolation concept and only terminated the test when the MGB had lasted longer than the max fuel endurance of the aircraft?
If a Glycol system fails to work as advertised, be it in cooling or just an indication that is working....then that machine has no "Run Dry" capability in reality.
So...if you want use some descriptive wording....or a design concept that requires coolant or trapped oil....is that a "Run Dry" Design?
I can't think you will ever get a MRGB to actually run completely dry for any significant time - too much load and too much heat to dissipate.
The UK mil Sea Kings had an emergency lube system which had an additional sump and used the torqumeter pumps to provide pressure to the top bearings in the MRGB following a double MRGB pump failure or significant oil leak - it certainly gave you more than 30 mins.
Sasless - that S-92 'isolation' concept was flawed since it didn't cover the detachment of the filter due to poor design. Without oil the S-92 MRGB failed at between 11 and 12 minutes.
The UK mil Sea Kings had an emergency lube system which had an additional sump and used the torqumeter pumps to provide pressure to the top bearings in the MRGB following a double MRGB pump failure or significant oil leak - it certainly gave you more than 30 mins.
Sasless - that S-92 'isolation' concept was flawed since it didn't cover the detachment of the filter due to poor design. Without oil the S-92 MRGB failed at between 11 and 12 minutes.
the 189 has 50 mins
Interesting discussion.
i personnally dont bother so much,
Actual run dry or trapped oil (Bell?) Is obvious best (non complicated)
Back-up systems are ok for me as long as they are proven to work when needed.
let's get back on topic?
SLB
i personnally dont bother so much,
Actual run dry or trapped oil (Bell?) Is obvious best (non complicated)
Back-up systems are ok for me as long as they are proven to work when needed.
let's get back on topic?
SLB
Crab,
You make my point for me.
The test by Sikorky allowed an extra delay in isolating the system....then carried on and was called off after the max fuel endurance was reached. They were testing their engineered system for certification and it worked fine. But we all know the rest of the story which enforces my position that if we say "Run Dry" it should mean "DRY".
Even those other "Trapped" fluid designs sound good but just as in the 92...the question has to be asked about even rare to the point of being an act of God kind of failure shifts you into being in a "DRY" situation.
If the drain plug were to remove itself by mystical reasons....would that cause a loss of lubricant? Sounds far fetched but then who would have guessed the 92 thing would happen? Lots of experts AFTER the fact knew of course but it made it into Service before it presented itself.
You make my point for me.
The test by Sikorky allowed an extra delay in isolating the system....then carried on and was called off after the max fuel endurance was reached. They were testing their engineered system for certification and it worked fine. But we all know the rest of the story which enforces my position that if we say "Run Dry" it should mean "DRY".
Even those other "Trapped" fluid designs sound good but just as in the 92...the question has to be asked about even rare to the point of being an act of God kind of failure shifts you into being in a "DRY" situation.
If the drain plug were to remove itself by mystical reasons....would that cause a loss of lubricant? Sounds far fetched but then who would have guessed the 92 thing would happen? Lots of experts AFTER the fact knew of course but it made it into Service before it presented itself.
Sasless - agreed but the FAA were fooled by it which is worrying.
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emergency or run dry capability does not help if the rotor falls off.
the problem here as I see it is to find a system that
in case of severe MGB failure, does not shear the rotor of the AC.
the weakest point on the LN-OJF was that the failure led to rotor
shear-off. no matter what else is broken on the AC this should not happen
Could it be avoided with 7 susp bars? 10? Donīt know.
a run dry capability would only cover one failure mode.
What is needed here is a system robust enough to cover every failure mode
the problem here as I see it is to find a system that
in case of severe MGB failure, does not shear the rotor of the AC.
the weakest point on the LN-OJF was that the failure led to rotor
shear-off. no matter what else is broken on the AC this should not happen
Could it be avoided with 7 susp bars? 10? Donīt know.
a run dry capability would only cover one failure mode.
What is needed here is a system robust enough to cover every failure mode
Crab.....the Sikorsky folks did not "fool" anyone.....the System fooled everyone including those administering the system.
If you recall my previous posts about what it is going to take to make things genuinely better....it will require a dropping of shields by everyone involved in the "system"....and a clean sheet review of processes, concepts, standards, and procedures.
Plainly, like every Chain....there are weak links.
Identifying the factors that lead to these weak links is the first step.
Let's look back over the Years....and all the changes that have been made that were seen to be "cures" but in time were found not to have done what they were supposed to do.
We have HUMS, Oil Analysis, Chip Plugs and all sorts of other ways of monitoring MGB's (for example) and despite a Fatal Accident involving the loss of a Rotor Head....and efforts to remedy the problems found by the investigation of that Crash....we now have another one where it is seen that we still do not have it right yet.
Engineers, with good intentions, saw the 92 Oil Filter Assembly to be fine...as did the FAA and other Authorities but we found despite all the folks involved in the process....there were real issues.
We see the same thing with the EC MGB....lots of very good and diligent folks sought and found a problem and did what they thought would end that situation.
Sadly, we are Humans....and therefore are prone to make mistakes.
Who, where, when, why, what, and how those mistakes are made is the issue we need to consider.
Sikorsky made a mistake thinking there would always be oil in the 92 Gearbox.
EC thought revamping the method by which their Gearbox is monitored would be the fix.
The authorities affirmed the two companies thinking.
Operators did as well.
So the question is.....how do we make the system truly effective?
If you recall my previous posts about what it is going to take to make things genuinely better....it will require a dropping of shields by everyone involved in the "system"....and a clean sheet review of processes, concepts, standards, and procedures.
Plainly, like every Chain....there are weak links.
Identifying the factors that lead to these weak links is the first step.
Let's look back over the Years....and all the changes that have been made that were seen to be "cures" but in time were found not to have done what they were supposed to do.
We have HUMS, Oil Analysis, Chip Plugs and all sorts of other ways of monitoring MGB's (for example) and despite a Fatal Accident involving the loss of a Rotor Head....and efforts to remedy the problems found by the investigation of that Crash....we now have another one where it is seen that we still do not have it right yet.
Engineers, with good intentions, saw the 92 Oil Filter Assembly to be fine...as did the FAA and other Authorities but we found despite all the folks involved in the process....there were real issues.
We see the same thing with the EC MGB....lots of very good and diligent folks sought and found a problem and did what they thought would end that situation.
Sadly, we are Humans....and therefore are prone to make mistakes.
Who, where, when, why, what, and how those mistakes are made is the issue we need to consider.
Sikorsky made a mistake thinking there would always be oil in the 92 Gearbox.
EC thought revamping the method by which their Gearbox is monitored would be the fix.
The authorities affirmed the two companies thinking.
Operators did as well.
So the question is.....how do we make the system truly effective?
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Originally Posted by [email protected]
I can't think you will ever get a MRGB to actually run completely dry for any significant time - too much load and too much heat to dissipate.
The UK mil Sea Kings had an emergency lube system which had an additional sump and used the torqumeter pumps to provide pressure to the top bearings in the MRGB following a double MRGB pump failure or significant oil leak - it certainly gave you more than 30 mins.
Sasless - that S-92 'isolation' concept was flawed since it didn't cover the detachment of the filter due to poor design. Without oil the S-92 MRGB failed at between 11 and 12 minutes.
The UK mil Sea Kings had an emergency lube system which had an additional sump and used the torqumeter pumps to provide pressure to the top bearings in the MRGB following a double MRGB pump failure or significant oil leak - it certainly gave you more than 30 mins.
Sasless - that S-92 'isolation' concept was flawed since it didn't cover the detachment of the filter due to poor design. Without oil the S-92 MRGB failed at between 11 and 12 minutes.
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Getting industry buy in to a never ending cost center over and above current cert requirements puts a very hard edge on "the continuous improvement model" -- for all that I agree on periodic review to get after some of those difficult trade offs that have to be made to get anything built
As for the cost impact to OEMs, if the result of the validation/analysis work demonstrates a solid case for implementing changes to the design certified by the FAA, then the FAA and OEM both should share the cost to correct the situation.
A great example of how recent technology developments can greatly improve the loss of lube capability of a legacy MRGB design, is shown in this presentation from 2009 describing the significantly increased high-temperature performance offered by the new C-64 gear steel alloy versus the existing gear steel alloys X-53 and 9310. The 500+degF increase in tempering temperature limit provides a huge advantage in loss of lube conditions. C64 did not even exist when the EC225 MRGB design was certified.
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The Truck Driver transporting that Gearbox in Australia died in the Accident.
So that will give you a good idea of what happened to the gearbox.
It's very possible the Conical housing was the initial cause. We may never know.
The fact the Gearbox was never scrapped, simply comes down to Greed!
Risk Analysis is a tricky game to play. Get it wrong and all of a sudden hundreds if not thousands of lives are effected and Millions if not Billions of loss come into play.
Those that get to play God in this way only ever get punished by way of the Karma God. It's a sad unaccountable World we live in.
Sikorsky made a mistake thinking there would always be oil in the 92 Gearbox.
Rubbish, this is a classic example of Greed and poor risk analysis at best
So that will give you a good idea of what happened to the gearbox.
It's very possible the Conical housing was the initial cause. We may never know.
The fact the Gearbox was never scrapped, simply comes down to Greed!
Risk Analysis is a tricky game to play. Get it wrong and all of a sudden hundreds if not thousands of lives are effected and Millions if not Billions of loss come into play.
Those that get to play God in this way only ever get punished by way of the Karma God. It's a sad unaccountable World we live in.
Sikorsky made a mistake thinking there would always be oil in the 92 Gearbox.
Rubbish, this is a classic example of Greed and poor risk analysis at best
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buzz66 ... hearing this was a fatal accident and already knowing the unit was damaged (they said some kind of, as yet unidentified, repairs were carried out) compounds my initial surprise that the MGB was returned to service.
Presumably the module in G-REDL had not been in a serious road accident or similar damage situation. Given that in both (flying) accidents the second stage planet gear appears to have failed, the news that road accident damage may, or may not, have contributed to the Bergen accident will be hard to establish in any definitive sense. Even if it can be it will hardly restore the reputation of the MGB design.