Sikorsky S-92: From Design to Operations
212 - I suppose it depends on whether they are commanded shutdowns (fadec freeze, fire, chip, loss of oil etc) or uncommanded.
Bronx - if you think its childish to be concerned about the apparently poor reliability of an aircraft then no, I have not tried to grow up.
busdriver - The engine family is historically fairly reliable but the trouble with reliability is that it can take a big hit from a minor design change. If your benchmark is the Huey then the 92 is smooth! The high nose attitude thing is nothing to do with comfort, but to do with forward visibility in the hover. If you are hovering over a pitching and rolling 3-masted yacht with the winchman dangling, its nice to be able to see as much as possible, including the mast top just ahead!
HC
Bronx - if you think its childish to be concerned about the apparently poor reliability of an aircraft then no, I have not tried to grow up.
busdriver - The engine family is historically fairly reliable but the trouble with reliability is that it can take a big hit from a minor design change. If your benchmark is the Huey then the 92 is smooth! The high nose attitude thing is nothing to do with comfort, but to do with forward visibility in the hover. If you are hovering over a pitching and rolling 3-masted yacht with the winchman dangling, its nice to be able to see as much as possible, including the mast top just ahead!
HC
HC, Well, I know of 3 uncommanded shutdowns, in what: 55,000 hours?
(1 fuel valve break away and 2 HP fuel pump failures through engine accessory gear box seizures)
(1 fuel valve break away and 2 HP fuel pump failures through engine accessory gear box seizures)
No, but a very nice CHC S92 called into Humberside a couple of days ago. Only 45 mins on the clock!! Straight out of the box. Most modern piece of kit ever to grace the Humberside base. 
Bristow Group Announces Eight New Aircraft Purchases
Monday, January 14, 2008 / Bristow Group
Bristow Group Inc. (NYSE: BRS), a leading provider of helicopter services to the offshore energy industry, today announced the acquisition of eight new aircraft. Bristow has exercised options to acquire two S-92 and three S-76C++ helicopters from Sikorsky Aircraft Corporation, a subsidiary of United Technologies Corp. (NYSE: UTX), and three EC225 helicopters from Eurocopter, a division of EADS. The combined value of these purchases is approximately $143 million to be funded with the proceeds of previously completed financings and future operating cash flows. Bristow maintains multi-year options to purchase additional aircraft from Sikorsky and Eurocopter as market conditions require.
Monday, January 14, 2008 / Bristow Group
Bristow Group Inc. (NYSE: BRS), a leading provider of helicopter services to the offshore energy industry, today announced the acquisition of eight new aircraft. Bristow has exercised options to acquire two S-92 and three S-76C++ helicopters from Sikorsky Aircraft Corporation, a subsidiary of United Technologies Corp. (NYSE: UTX), and three EC225 helicopters from Eurocopter, a division of EADS. The combined value of these purchases is approximately $143 million to be funded with the proceeds of previously completed financings and future operating cash flows. Bristow maintains multi-year options to purchase additional aircraft from Sikorsky and Eurocopter as market conditions require.
HC
Not sure.
This is the design requirement (CS29):
CS 29.927 Additional tests
(c) Lubrication system failure. For lubrication systems required for proper operation of rotor drive systems, the following apply:
(1) Category A. Unless such failures are extremely remote, it must be shown by test that any failure which results in loss of lubricant in any normal use lubrication system will not prevent continued safe operation, although not necessarily without damage, at a torque and rotational speed prescribed by the applicant for continued flight, for at least 30 minutes after perception by the flight crew of the lubrication system failure or loss of lubricant.
So it would appear that the argument
has been used, because there are no equivelent safety findings stated in the TCDS (for the MGB lubrication system.)
If the failure is not considered remote, then this is the procedure for dmonstrating compliance: (from AC 29-2C)
b. Procedures.
(1) Section 29.927(c) prescribes a test which is intended to demonstrate that
no hazardous failure or malfunction will occur in the event of a major rotor drive system lubrication failure. The lubrication failure should not impair the ability of the crew to continue safe operation of Category A rotorcraft for at least 30 minutes after perception of the failure by the flight crew. For Category B rotorcraft, safe operation under autorotative conditions should continue for at least 15 minutes. Near the completion of the lubrication failure test, an input torque should be applied for 15 seconds to simulate a minimum power landing following autorotation. Some damage to rotor drive system
components is acceptable after completion of the lubrication system testing. The lubrication system failure modes of interest are usually limited to failure of bearings, gears, splines, clutches, etc., of pressure lubricated transmissions and/or gearboxes. A bench test (transmission test rig) is commonly used to demonstrate compliance with this rule. Since this is a test of the capability of the residual oil in the transmission to provide limited lubrication, a critical entry condition for the test should be established.
The transmission lubricating oil should be drained while the transmission is operating at maximum normal speed and nominal cruise torque (reacted as appropriate at the main mast and tail rotor output quills). A vertical load should be applied at the mast, equal to the gross weight of the rotorcraft at 1g, and the lubricant should be at the maximum temperature limit. Upon illumination of the low oil pressure warning required by § 29.1305, reduce the input torque for Category A rotorcraft to the minimum torque necessary to sustain flight at the maximum gross weight and the most efficient flight
conditions. To complete the test, apply an input torque to the transmission for approximately 25 seconds to simulate an autorotation. The last 10 seconds (of the 25 seconds) should be at the torque required for a minimum power landing. A successful demonstration may involve limited damage to the transmission, provided it is determined that the autorotative capabilities of the rotorcraft were not significantly impaired.
What would be interesting to know is, if the argument 'extremely remote' has been used, how continuing demonstration of this assertion is achieved. i.e. if in service it is found that aircraft are suffering MGB oil leaks - which would not be contained by use of the MGB Bypass valve - then the assertion would appear to be incorrect. Particularly if the leaks are not from a common source.
This is the design requirement (CS29):
CS 29.927 Additional tests
(c) Lubrication system failure. For lubrication systems required for proper operation of rotor drive systems, the following apply:
(1) Category A. Unless such failures are extremely remote, it must be shown by test that any failure which results in loss of lubricant in any normal use lubrication system will not prevent continued safe operation, although not necessarily without damage, at a torque and rotational speed prescribed by the applicant for continued flight, for at least 30 minutes after perception by the flight crew of the lubrication system failure or loss of lubricant.
So it would appear that the argument
Unless such failures are extremely remote
If the failure is not considered remote, then this is the procedure for dmonstrating compliance: (from AC 29-2C)
b. Procedures.
(1) Section 29.927(c) prescribes a test which is intended to demonstrate that
no hazardous failure or malfunction will occur in the event of a major rotor drive system lubrication failure. The lubrication failure should not impair the ability of the crew to continue safe operation of Category A rotorcraft for at least 30 minutes after perception of the failure by the flight crew. For Category B rotorcraft, safe operation under autorotative conditions should continue for at least 15 minutes. Near the completion of the lubrication failure test, an input torque should be applied for 15 seconds to simulate a minimum power landing following autorotation. Some damage to rotor drive system
components is acceptable after completion of the lubrication system testing. The lubrication system failure modes of interest are usually limited to failure of bearings, gears, splines, clutches, etc., of pressure lubricated transmissions and/or gearboxes. A bench test (transmission test rig) is commonly used to demonstrate compliance with this rule. Since this is a test of the capability of the residual oil in the transmission to provide limited lubrication, a critical entry condition for the test should be established.
The transmission lubricating oil should be drained while the transmission is operating at maximum normal speed and nominal cruise torque (reacted as appropriate at the main mast and tail rotor output quills). A vertical load should be applied at the mast, equal to the gross weight of the rotorcraft at 1g, and the lubricant should be at the maximum temperature limit. Upon illumination of the low oil pressure warning required by § 29.1305, reduce the input torque for Category A rotorcraft to the minimum torque necessary to sustain flight at the maximum gross weight and the most efficient flight
conditions. To complete the test, apply an input torque to the transmission for approximately 25 seconds to simulate an autorotation. The last 10 seconds (of the 25 seconds) should be at the torque required for a minimum power landing. A successful demonstration may involve limited damage to the transmission, provided it is determined that the autorotative capabilities of the rotorcraft were not significantly impaired.
What would be interesting to know is, if the argument 'extremely remote' has been used, how continuing demonstration of this assertion is achieved. i.e. if in service it is found that aircraft are suffering MGB oil leaks - which would not be contained by use of the MGB Bypass valve - then the assertion would appear to be incorrect. Particularly if the leaks are not from a common source.
HC,
You might not get to clapping too hard.....in time the way the US Dollar is going the 92 will cost peanuts compared to the 225.
What effect that will have on Operating Costs can only be imagined....as the spares will also decrease in costs.
You might not get to clapping too hard.....in time the way the US Dollar is going the 92 will cost peanuts compared to the 225.
What effect that will have on Operating Costs can only be imagined....as the spares will also decrease in costs.
Run dry - Not strictly so.
If I remember correctly from previous discussions on this topic…..in the event of an external [XMSN] oil leak, the oil system closes off external oil flow to the oil cooler thereby leaving the remaining un-cooled oil to lubricate the transmission.
As it’s FAR/JAR 29 certified, I guess the OEM was able to satisfy both AA’s that safe operation could be demonstrated for a minimum of 30-minutes.
If I remember correctly from previous discussions on this topic…..in the event of an external [XMSN] oil leak, the oil system closes off external oil flow to the oil cooler thereby leaving the remaining un-cooled oil to lubricate the transmission.
As it’s FAR/JAR 29 certified, I guess the OEM was able to satisfy both AA’s that safe operation could be demonstrated for a minimum of 30-minutes.
Hi SAS
Yes, the dollar remains weak though its back under 2 to the pound at the moment. In the mean time, I think Sikorsky has put its prices up faster than EC so the price gap is not as bad as it could have been if the "introductory offer" pricing of the 92 had remained.
Even so the 225 is definitely the more expensive to buy and run. Its fortunate that our management and customers don't all fall into the category of "knowing the price of everything and the value of nothing" - ie they are not accountants!
The 92 has had a disappointingly high level of serious failures since introduction, the 225 has not. IMHO that vindicates Eurocopters policy of "technology injection" where they take a mature product and add new technology at useful places whilst continuing to use mature technology where appropriate. NL will tell you that this means it doesn't fully comply with FAR/CS29 and he is right, but that does not mean the 92 is safer in practice. As I have said before, I would rather not crash in a non-crashworthy helicopter than crash in a crashworthy one!
Even the 92 does not in fact comply fully with FAR29 - it just pretends to as we are seeing in the discussions on this thread. Naughty Geoffers
HC
Yes, the dollar remains weak though its back under 2 to the pound at the moment. In the mean time, I think Sikorsky has put its prices up faster than EC so the price gap is not as bad as it could have been if the "introductory offer" pricing of the 92 had remained.
Even so the 225 is definitely the more expensive to buy and run. Its fortunate that our management and customers don't all fall into the category of "knowing the price of everything and the value of nothing" - ie they are not accountants!
The 92 has had a disappointingly high level of serious failures since introduction, the 225 has not. IMHO that vindicates Eurocopters policy of "technology injection" where they take a mature product and add new technology at useful places whilst continuing to use mature technology where appropriate. NL will tell you that this means it doesn't fully comply with FAR/CS29 and he is right, but that does not mean the 92 is safer in practice. As I have said before, I would rather not crash in a non-crashworthy helicopter than crash in a crashworthy one!
Even the 92 does not in fact comply fully with FAR29 - it just pretends to as we are seeing in the discussions on this thread. Naughty Geoffers
HC
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HC
The EC225 is, as we all know a development of the 332L family. While it may now be a mature and safe helicopter (and I applaud that) as a result of 25 years of evolutionary change and progress, the early AS332Ls were neither a paragon of reliability or safety.
25 years have passed and lessons have been learned leading to the product you obviously enjoy today. Much of the progress was due to the experience and knowledge of "Mother Bristow" and their constructive input to Aerospatiale as they were then.
Maybe many here don't remember the 70 main transmission changes in the first year or two, frequent diversions for cowl open warnings, frequency adapters letting go, disappearing doghouses, tail rotor pitch link failures, frequent MGB Cool warnings, and an accident caused by a tail drive shaft hinge pin coming adrift. Even the mighty Makila in the dim and distant past could lose all its oil and have to be shut down.
Genuine constructive criticism from you and those in similar positions who have your type of operational background is accepted and will be no doubt listened to by wise men in the interests of product improvement and, more importantly, the quest for operational safety.
While it is evident that you (and others here) have a favourite "brand", using the art of sophistry to make a point is counter productive.
Elevate the tone of the discussion and both you (and others here) may win even more respect. Continuation of discussion at the current level is beginning to make many of us yawn.
The EC225 is, as we all know a development of the 332L family. While it may now be a mature and safe helicopter (and I applaud that) as a result of 25 years of evolutionary change and progress, the early AS332Ls were neither a paragon of reliability or safety.
25 years have passed and lessons have been learned leading to the product you obviously enjoy today. Much of the progress was due to the experience and knowledge of "Mother Bristow" and their constructive input to Aerospatiale as they were then.
Maybe many here don't remember the 70 main transmission changes in the first year or two, frequent diversions for cowl open warnings, frequency adapters letting go, disappearing doghouses, tail rotor pitch link failures, frequent MGB Cool warnings, and an accident caused by a tail drive shaft hinge pin coming adrift. Even the mighty Makila in the dim and distant past could lose all its oil and have to be shut down.
Genuine constructive criticism from you and those in similar positions who have your type of operational background is accepted and will be no doubt listened to by wise men in the interests of product improvement and, more importantly, the quest for operational safety.
While it is evident that you (and others here) have a favourite "brand", using the art of sophistry to make a point is counter productive.
Elevate the tone of the discussion and both you (and others here) may win even more respect. Continuation of discussion at the current level is beginning to make many of us yawn.
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212 man and HC do make valid points, particularly concerning the rate of failures of the GE CT7. After all in the military as the T700 on the Blackhawk/Apache and in civil use as the CT7 on the 214ST it seems to have been much more reliable. Does 212 man know of any major design changes made to it as fitted in the S92? If the engines are now failing to meet the CS/FAR requirement for a failure probability of 1x10-5 per flight hour then its operation in the North Sea may well be at risk if the JAA take an interest and in the USA the larger oil companies may be worried about being sued over a lack of duty of care if the required criteria of ICAO attachment A on Risk Assessment are shown to no longer be valid. I'm sure Sikorsky and GE must be taking the matter seriously by now and if past experience is anything to go by, they'll be burning the midnight oil trying to find a fix in case they get hit in the pocketbook by either a reduction in forecast orders or the prospect of a Class action if another failure leads to the death or injury of someone after it's known not to be meeting required reliability criteria.
I have no ax to grind regarding either aircraft as I fly neither Sikorsky, nor Eurocopter products at present and don't expect to in the near future.
I have no ax to grind regarding either aircraft as I fly neither Sikorsky, nor Eurocopter products at present and don't expect to in the near future.
LE I have to agree with much of what you say. Only 2 things I don't agree with:
1) Where have I used the art of Sophistry (aka fallacious arguments - had to look it up!)? - OK a touch or sarcasm and/or humour from time to time but I try to base my serious arguments on fact.
2) If its making you yawn, there is no need to read it. That said, I admit it does go round and round a bit but new information does arise all the time, eg the recent spate of engine accessory drive failures. Oh alright then I admit it - but I just can't help myself!
HC
1) Where have I used the art of Sophistry (aka fallacious arguments - had to look it up!)? - OK a touch or sarcasm and/or humour from time to time but I try to base my serious arguments on fact.
2) If its making you yawn, there is no need to read it. That said, I admit it does go round and round a bit but new information does arise all the time, eg the recent spate of engine accessory drive failures. Oh alright then I admit it - but I just can't help myself!
HC
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HC
I ain't seen any humor but you're right about the sarcasm except it's not a touch and it's not from time to time.
The problem is lots of us want to read this thread and you're spoiling it with your constant childish comments. There's been almost 1000 posts and almost 100,000 views since it started. We've followed it since a very early stage just like it says in the title and because a key guy in the development and introduction of a new helicopter is one of us.
Can't help yourself?
Yes you can. Just stop behaving like a selfish child and consider other people. Then maybe we can raise the discussion back to the level it was before.
B.
1) OK a touch or sarcasm and/or humour from time to time
2) If its making you yawn, there is no need to read it. That said, I admit it does go round and round a bit but new information does arise all the time, eg the recent spate of engine accessory drive failures. Oh alright then I admit it - but I just can't help myself!
Can't help yourself?
Yes you can. Just stop behaving like a selfish child and consider other people. Then maybe we can raise the discussion back to the level it was before.B.
We use Senheiser HMEC322s with power supply wired in. Good passive qualities as well as the ANR. Similar weight and comfort to the Peltor.