Sikorsky S-92: From Design to Operations
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S92 Dry run MGB.
Yes the S92 has a dry run MGB. It was improved from the Blackhawk MGB. It is good for 1hour.
THe loss of oil pressure is a secondary failure of the real failure. Time will tell once the A/C is recovered.
THe loss of oil pressure is a secondary failure of the real failure. Time will tell once the A/C is recovered.
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rigpiggy, no helicopter has a clutch between the main rotor gearbox and the rotor system (I think that is what you are getting at). Not familiar with the 92's drive train, but a clutch system is included between each engine and the main rotor gearbox.
Heli-MGB-Tech
Its a pity to make your first ever post so dogmatic and yet so wrong. The S92main gearbox, like most other large helicopters, has no dry run time. Some other large helicopters use an emergency lubrication/cooling system to give additional flight time following complete loss of normal lubrication system, but the S92 is not one of those.
HC
Its a pity to make your first ever post so dogmatic and yet so wrong. The S92main gearbox, like most other large helicopters, has no dry run time. Some other large helicopters use an emergency lubrication/cooling system to give additional flight time following complete loss of normal lubrication system, but the S92 is not one of those.
HC
Brian that's what I figured, but without asking I couldn't be sure
From Pilot DAR
The gearbox design, included a block of wax within, which would melt at a suitably high temperature after oil loss for whatever reason. Cast into the wax were spring loaded electrical contacts, which closed once the wax melted. The closed contacts told the pilot that the gearbox was now being lubricated by the wax, and down would be good.
From Pilot DAR
The gearbox design, included a block of wax within, which would melt at a suitably high temperature after oil loss for whatever reason. Cast into the wax were spring loaded electrical contacts, which closed once the wax melted. The closed contacts told the pilot that the gearbox was now being lubricated by the wax, and down would be good.
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Brian, I think you'll find HC is fairly conversant with the FAR/CS-29 requirements.
The relevant statement is in the opening line:
A more pertinent question might be "what standard is used to demonstrate extreme remoteness" especially in a new design?
Heli-MGB-tech, could you delete your post? It is incorrect in every regard and is possibly one of the most mis-informed comments I've seen on this website - and that' saying something!
The relevant statement is in the opening line:
Unless such failures are extremely remote
Heli-MGB-tech, could you delete your post? It is incorrect in every regard and is possibly one of the most mis-informed comments I've seen on this website - and that' saying something!
Brian
This issue has been covered many times before and in some detail.
You are correct in saying that the aircraft has been accepted by the FAA as meeting the requirements of FAR29 amdt 47. However the gearbox does not have 30 mins "run dry" capability. It will not run for 30 minutes with NO oil.
We can be clever and play around with the words. However the facts are pretty simple, or at least I think they are
This issue has been covered many times before and in some detail.
You are correct in saying that the aircraft has been accepted by the FAA as meeting the requirements of FAR29 amdt 47. However the gearbox does not have 30 mins "run dry" capability. It will not run for 30 minutes with NO oil.
We can be clever and play around with the words. However the facts are pretty simple, or at least I think they are
CCXXV
Isn’t the S-92 MGB straight out of the Black Hawk, with a slightly higher power rating?
If the case, then with some 4 million flight hours to its name, I’d have thought SAC would have utilised this data when requesting approvals from the AA’s?
A more pertinent question might be "what standard is used to demonstrate extreme remoteness" especially in a new design?
If the case, then with some 4 million flight hours to its name, I’d have thought SAC would have utilised this data when requesting approvals from the AA’s?
So as I understand it (from this and other threads):
Sikorsky managed to persuade the FAA that their S92 gearbox, unlike anyone elses, was immune to any failure except 'an extremely remote one'.
There has been a series of incidents (up until now over land), where failures other than an external pipe leak (if this is what the external isolation valve is meant to deal with) have led to emergency landings.
One could conclude that the MRGB is not as brilliantly engineered as Sikorsky believed and that some serious litigation is inbound if it is proved to be the cause of the very sad Newfoundland crash.
Sikorsky managed to persuade the FAA that their S92 gearbox, unlike anyone elses, was immune to any failure except 'an extremely remote one'.
There has been a series of incidents (up until now over land), where failures other than an external pipe leak (if this is what the external isolation valve is meant to deal with) have led to emergency landings.
One could conclude that the MRGB is not as brilliantly engineered as Sikorsky believed and that some serious litigation is inbound if it is proved to be the cause of the very sad Newfoundland crash.
The RFM indirectly acknowledges that there is no run dry capability. The emergency drill dealing with MGB low oil pressure states that if the pressure falls below 5psi then LAND IMMEDIATELY.
So the 'extremely remote failure' that didn't require a run dry capability to get certification or warrant an emergency lube system still has an emergency drill in the RFM, just in case. Is this not the equivalent of having a 'wing falling off drill' in a FW since that is also an 'extremely remote failure'.?
And all this on an aircraft marketed for over-water use
And all this on an aircraft marketed for over-water use
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MGB
There has been a series of incidents (up until now over land), where failures other than an external pipe leak (if this is what the external isolation valve is meant to deal with) have led to emergency landings.
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Incidents with S-92 Main gear box
1. Norsk Helikopter had one incident in the North Sea, early days of S-92, regular revenue flight, both MGB oil pumps failed, landed on a nearby rig.
What others? Please copy and paste, want to make a list of this..
What others? Please copy and paste, want to make a list of this..
Northseaspray,
I think you had better stop there. It wasn't a double oil pump failure. Just one pump failed.
Crab, the drill is for Low MGB Oil Pressure. Not sure I share you "shock-horror" response. I am sure every helicopter out there has a similar drill??
Rotorknight, I'm not sure what in the Sikorsky engine fire drill you do not like? However that is irrelevant, your company can have a fire drill that they think is suitable. If you have any complaints you can direct it at them. And please don't respond that everything in the RFM has to be followed verbatim, only the limitations section is mandatory.
C'mon guys, this is getting silly. Sensible debate and criticism where warranted is fantastic, but this is like listening to a bunch of 11 year olds talking about their sex lives
I think you had better stop there. It wasn't a double oil pump failure. Just one pump failed.
Crab, the drill is for Low MGB Oil Pressure. Not sure I share you "shock-horror" response. I am sure every helicopter out there has a similar drill??
Rotorknight, I'm not sure what in the Sikorsky engine fire drill you do not like? However that is irrelevant, your company can have a fire drill that they think is suitable. If you have any complaints you can direct it at them. And please don't respond that everything in the RFM has to be followed verbatim, only the limitations section is mandatory.
C'mon guys, this is getting silly. Sensible debate and criticism where warranted is fantastic, but this is like listening to a bunch of 11 year olds talking about their sex lives
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Variable load,with regards to the fire drill,can you give me a brilliant tip on how to confirm we actually have a fire if we get the lovely aural warning and the light,since there are no mirrors fitted,you can't actually stick your head out of the window either,and don't tell me now that a 360 is going to be the miracle trick here.
I think what a lot of people here are trying to say is,that maybe they are not ultimately comfortable flying this machine.
I guess you are so I wish you all the best,and hope you keep on enjoying it(without a lot of the physical problems people seem to get,and this is a FACT)
I think what a lot of people here are trying to say is,that maybe they are not ultimately comfortable flying this machine.
I guess you are so I wish you all the best,and hope you keep on enjoying it(without a lot of the physical problems people seem to get,and this is a FACT)
Would we fly any aircraft that we thought a main transmission failure was anything less than a "remote probability"? How does one define "remote probability"? Is it an objective definition based upon empirical data or a subjective one based upon consideration of non-empirical data?
How did the FAA arrive at their definition I wonder?
How did the FAA arrive at their definition I wonder?
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RFM and Emergency Checklists
Fire Drills - I am a lot happier when the RFM says 'Confirm Engine Fire' (AW139) than one that directs me to obey the light regardless (S76). It provides the opportunity for some options.
General - You may think that the Limitations section of the RFM is the only 'mandatory' section but you just try arguing your case when you are stuck in the witness box and one barrister after another asks if you think you know better than the bloke that designed and built it. Simply being in the right will cut little ice in front of people who do not understand the minutiae of our world.
If you want a good way out then put the checklist revision into your ops manual and get it 'accepted' (NAA will never 'approve' anything other than your FTL scheme and your tech log - in UK anyway). At least that way you can argue that your revision has been reviewed by a competent body.
G
PS. When I use the word 'competent' to describe the aviation authorities there is absolutely not one jot of sarcasm in my words, really.
General - You may think that the Limitations section of the RFM is the only 'mandatory' section but you just try arguing your case when you are stuck in the witness box and one barrister after another asks if you think you know better than the bloke that designed and built it. Simply being in the right will cut little ice in front of people who do not understand the minutiae of our world.
If you want a good way out then put the checklist revision into your ops manual and get it 'accepted' (NAA will never 'approve' anything other than your FTL scheme and your tech log - in UK anyway). At least that way you can argue that your revision has been reviewed by a competent body.
G
PS. When I use the word 'competent' to describe the aviation authorities there is absolutely not one jot of sarcasm in my words, really.
Last edited by Geoffersincornwall; 16th Mar 2009 at 13:46.
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Northseaspray,
I think you had better stop there. It wasn't a double oil pump failure. Just one pump failed
I think you had better stop there. It wasn't a double oil pump failure. Just one pump failed
Anyway the the crew decided to land on a rig, fortunately this time there was one nearby.