Sikorsky S-92: From Design to Operations
Back to some rather strange statements by Geoffers! Can someone, perhaps Geoffers himself explain what is meant by "PC2e clearance 'pulled'"
My understanding is that PC2e is now something of an operator voluntary code. In fact I would go further and say that it's use offshore is limited to a couple of S92 Shell driven operations in SE Asia.
Can someone provide me with some examples of PC2e being used elsewhere with another aircraft?
In fact, back to Geoffers comment, it is not PC2e that has a clearance, it is the use of "pure" PC2 offshore that is reliant upon engine reliability stats!
My understanding is that PC2e is now something of an operator voluntary code. In fact I would go further and say that it's use offshore is limited to a couple of S92 Shell driven operations in SE Asia.
Can someone provide me with some examples of PC2e being used elsewhere with another aircraft?
In fact, back to Geoffers comment, it is not PC2e that has a clearance, it is the use of "pure" PC2 offshore that is reliant upon engine reliability stats!
UH-60 "Jelly" Lubrication
SASless, we initially intended using grease lubrication for the tail/intermediate boxes on the UTTAS ( UH-60 ), but discovered localized lubrication problems on the ground test vehicle that were unsolvable with the time available and so we switched back to oil. As you may recall, this was a competitive fly-off with Boeing and so we didn't have a lot of wiggle room to chase this issue down.
Thanks,
John Dixson
Thanks,
John Dixson
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PC2e
Variable
I was waiting for Jim to come up with the definitive reply which I'm sure will be 100% whereas mine will be a little garbled.
You may remember that the JAA has aspirations to make PC1 mandatory for all operations in hostile environments. Their attempt foundered on the difficulties associated with the obstacle environment offshore and the inability of the industry to create an environment that was in any way compliant.
The then accepted protocol of using PC2 with exposure was not deemed to be acceptable because it was too wishy-washy and slack. Another version was hatched in which exposure was only accepted if the reliability of the engines was quantified and maintenance procedures were elevated by using HUMS or similar/equivalent engine monitoring equipment.
The level of engine reliability required the (airframe) manufacturers to publish a statement that their engines complied with this level of reliability.
No statement = no ability to operate at PC2 weights in hostile environments unless the weight was low enough to demonstrate that an engine failure after TDP would NOT result in a deck-edge strike or a ditching. Landing manoeuvres had a similar restriction.
My understanding was these requirements (originally posted in NPA 38 to JAROPS 3) were running against a timetable but I've lost touch with where we are with that now.
Seems to me that if an airframer had to withdraw his reliability statement then those operating that type in hostile environments would have to reduce their take off weight to allow a safe OEI (non-ditching) profile.
Jim will correct me or fill in the gaps when he's finished his fish supper.
G
I was waiting for Jim to come up with the definitive reply which I'm sure will be 100% whereas mine will be a little garbled.
You may remember that the JAA has aspirations to make PC1 mandatory for all operations in hostile environments. Their attempt foundered on the difficulties associated with the obstacle environment offshore and the inability of the industry to create an environment that was in any way compliant.
The then accepted protocol of using PC2 with exposure was not deemed to be acceptable because it was too wishy-washy and slack. Another version was hatched in which exposure was only accepted if the reliability of the engines was quantified and maintenance procedures were elevated by using HUMS or similar/equivalent engine monitoring equipment.
The level of engine reliability required the (airframe) manufacturers to publish a statement that their engines complied with this level of reliability.
No statement = no ability to operate at PC2 weights in hostile environments unless the weight was low enough to demonstrate that an engine failure after TDP would NOT result in a deck-edge strike or a ditching. Landing manoeuvres had a similar restriction.
My understanding was these requirements (originally posted in NPA 38 to JAROPS 3) were running against a timetable but I've lost touch with where we are with that now.
Seems to me that if an airframer had to withdraw his reliability statement then those operating that type in hostile environments would have to reduce their take off weight to allow a safe OEI (non-ditching) profile.
Jim will correct me or fill in the gaps when he's finished his fish supper.
G
PC2e will be required for operations offshore in a hostile environment from 2010. PC2 with exposure will be permitted after that in a non-hostile environment.
Profiles for PC2e are provided by Sikorsky S92 and S76C+ and C++; by Agusta for the AW139 (just about to hit the street); and by Bell for the B412EP. Any other manufacturer's helideck Cat A procedure could be used when the environment does not permit, or deck size is too small, for compliance.
Generally speaking, reliability is required to be established (in fact risk assessment) whenever exposure is to be approved (singles and multis; onshore and offshore). In fact VL you had it completely about face; Pure PC2 is the only one which does not require approval for exposure (it does require a profile which guarantees 'deck-edge clearance' but does not require drop down to be calculated). PC2 with exposure and PC2e both do (as does PC3 with exposure).
I say generally because it is not yet clear whether the reliability assessment (and UMS) will be required for HEMS operations in PC2 to the HEMS Operating Site; or for operations in PC3 over a hostile environment, post EASA.
Jim
Profiles for PC2e are provided by Sikorsky S92 and S76C+ and C++; by Agusta for the AW139 (just about to hit the street); and by Bell for the B412EP. Any other manufacturer's helideck Cat A procedure could be used when the environment does not permit, or deck size is too small, for compliance.
Generally speaking, reliability is required to be established (in fact risk assessment) whenever exposure is to be approved (singles and multis; onshore and offshore). In fact VL you had it completely about face; Pure PC2 is the only one which does not require approval for exposure (it does require a profile which guarantees 'deck-edge clearance' but does not require drop down to be calculated). PC2 with exposure and PC2e both do (as does PC3 with exposure).
I say generally because it is not yet clear whether the reliability assessment (and UMS) will be required for HEMS operations in PC2 to the HEMS Operating Site; or for operations in PC3 over a hostile environment, post EASA.
Jim
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According to CBC
Operators of all Sikorsky S-92A helicopters around the world must immediately replace the mounting studs in the gearboxes, the Federal Aviation Administration ruled Friday in the aftermath of a helicopter crash off the coast of Newfoundland.
The ruling came after the Transportation Safety Board of Canada ruled that the Sikorsky helicopter that crashed on March 12, killing 17 people, had a broken main gearbox filter bowl assembly mounting stud
Operators of all Sikorsky S-92A helicopters around the world must immediately replace the mounting studs in the gearboxes, the Federal Aviation Administration ruled Friday in the aftermath of a helicopter crash off the coast of Newfoundland.
The ruling came after the Transportation Safety Board of Canada ruled that the Sikorsky helicopter that crashed on March 12, killing 17 people, had a broken main gearbox filter bowl assembly mounting stud
The Telegram - St. John?s, NL: Local News | TSB finds faulty mounting stud on crashed helicopter gearbox filter bowl assembly
"The Transportation Safety Board announced today it has found a broken main gearbox filter bowl assembly mounting stud following initial examination of the wreckage of the Cougar Sikorsky S92 A helicopter that crashed into the Atlantic Ocean off St. John’s last week.
As a result, a worldwide directive has been issued to ground all Sikorsky S92 A helicopters, until all titanium studs are replaced with steel mounting studs.
More details to follow...."
and..
The Telegram - St. John?s, NL: Local News | Update: All Sikorsky S-92As worldwide to be grounded
"Regulators are issuing an emergency airworthiness directive grounding all Sikorsky S-92A helicopters until a problem with the chopper’s main gearbox filter bowl assembly can be fixed.
Transportation Safety Board (TSB) investigators found a broken main gearbox filter bowl assembly on the Cougar S-92A that crashed in the Atlantic Ocean 55 kilometres from Newfoundland last week.
The accident killed 17 people.
On Jan. 28, 2009, Sikorsky issued an alert service bulletin, or ASB, indicating the bowl assembly problem should be fixed, by replacing titanium studs with steel studs.
ASBs are sent by Sikorsky directly to owners and operators of its choppers.
January’s ASB advised that the fix should be completed within one year, or the next 1,250 flight hours, whichever came first.
The safety board announced late Friday afternoon that the Federal Aviation Administration (FAA) will require the improved studs be installed in all Sikorsky S-92As before they can fly again.
Airworthiness directives are mandatory, and require that certain safety issues are addressed.
More to follow."
"The Transportation Safety Board announced today it has found a broken main gearbox filter bowl assembly mounting stud following initial examination of the wreckage of the Cougar Sikorsky S92 A helicopter that crashed into the Atlantic Ocean off St. John’s last week.
As a result, a worldwide directive has been issued to ground all Sikorsky S92 A helicopters, until all titanium studs are replaced with steel mounting studs.
More details to follow...."
and..
The Telegram - St. John?s, NL: Local News | Update: All Sikorsky S-92As worldwide to be grounded
"Regulators are issuing an emergency airworthiness directive grounding all Sikorsky S-92A helicopters until a problem with the chopper’s main gearbox filter bowl assembly can be fixed.
Transportation Safety Board (TSB) investigators found a broken main gearbox filter bowl assembly on the Cougar S-92A that crashed in the Atlantic Ocean 55 kilometres from Newfoundland last week.
The accident killed 17 people.
On Jan. 28, 2009, Sikorsky issued an alert service bulletin, or ASB, indicating the bowl assembly problem should be fixed, by replacing titanium studs with steel studs.
ASBs are sent by Sikorsky directly to owners and operators of its choppers.
January’s ASB advised that the fix should be completed within one year, or the next 1,250 flight hours, whichever came first.
The safety board announced late Friday afternoon that the Federal Aviation Administration (FAA) will require the improved studs be installed in all Sikorsky S-92As before they can fly again.
Airworthiness directives are mandatory, and require that certain safety issues are addressed.
More to follow."
Assuming this is the cause of the death of 17 people and critical injuries to one other.....which would suggest it is one very critical "stud"....why would the ASB grant ONE YEAR or 1250 FLIGHT HOURS to make the fix?
Will someone explain (can anyone explain) this kind of thinking?
How many times over the years have we seen such ASB's, AD's from the FAA and/or Manufacturers?
What happened to plain old commonsense......like asking the question..."If this defect/malfunction occurs....can it ... a) Kill someone, b) gravely injure someone, c) slightly injure someone, or d) just scare hell out of someone?
Will someone explain (can anyone explain) this kind of thinking?
How many times over the years have we seen such ASB's, AD's from the FAA and/or Manufacturers?
What happened to plain old commonsense......like asking the question..."If this defect/malfunction occurs....can it ... a) Kill someone, b) gravely injure someone, c) slightly injure someone, or d) just scare hell out of someone?
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Can someone really confirm a worldwide grounding. As far as I m aware my company is still flying, although I am off at the moment. This will have serious ramifications if it is the case, and I am also curious as to exactly what fault has been found, as descriptions continue to be a little vague.
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Four would be usual. When one breaks the sealing would fail and oil would flow out. If you make an immediate landing you will make the water / land alive. If you decide to count to 30...RIP
Three studs clamp the oil filter "can" to the MGB casing. The oil filter housing has a triangular flange that goes over the three studs coming out of the MGB (studs are arranged in a triangle on the three corners of the flange). A couple of O-rings seal it.
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What if the root cause is the filter bowl mounting stud?
Surely better to err on the side of caution than have the risk of yet another failure. With no MGB dry run time contingency I for one would not set foot in a S-92a until the titanium bolts were replaced with steel ones.
Should have been done as a precautionary measure in January.
Do not forget that the TSB has not concluded that this was the root cause failure mode.
Should have been done as a precautionary measure in January.
Do not forget that the TSB has not concluded that this was the root cause failure mode.
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Though not confirmed as the root cause certainly a very wise and timely decision. Was the reason for the ASB covering the replacement and the timeframe for compliance previously noted and discussed? In hindsight, back to a familiar topic of SB verses ASB/AD, the deciding factors and possible implications. Developments from the continuing investigation are eagerly awaited by all I am sure.
Outhouse.
Outhouse.
Last edited by outhouse; 21st Mar 2009 at 06:02.
There are many reasons for the stud to have failed and not to have been the root cause i.e. overstress due to differential thermal expansion, impact shock, etc.. Even if one stud failed one would hope the "o" ring was thick enough to provide some protection against such a rapid, and apparently total, loss of lubrication.
Whatever the final analysis shows it appears the processes in place failed in this case. This is so similar to the processes that led to Challenger. Everyone, should read the linked document from one of the greatest minds we have known. He puts forth the actual root causes of that tragedy in such a clear eye opening way. All design engineering, regulatory, and industry mangement types should be required to memorize it.
http://science.ksc.nasa.gov/shuttle/...Appendix-F.txt
The Sultan
Whatever the final analysis shows it appears the processes in place failed in this case. This is so similar to the processes that led to Challenger. Everyone, should read the linked document from one of the greatest minds we have known. He puts forth the actual root causes of that tragedy in such a clear eye opening way. All design engineering, regulatory, and industry mangement types should be required to memorize it.
http://science.ksc.nasa.gov/shuttle/...Appendix-F.txt
The Sultan
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Though not confirmed as the root cause certainly a very wise and timely decision. Was the reason for the ASB covering the replacement and the timeframe for compliance previously noted and discussed?
I think you'll find that when they say 'root cause' they don't mean that they are looking for some other failure that could have caused teh accident, they mean reasons for the studs shearing in this specific case. Quite clearly, as has been proven and is obvious to anyone who knows the system, this failure WILL RESULT IN TOTAL OIL LOSS unless the aircraft is landed or ditched before that happens.
Could all those who want to pursue the 30 minute run dry argument take a moment to reflect - it aint so!
I guess this will re-ignite the 'extremely remote' discussion - fundamentally the design can probably be shown to meet this clause, it's the choice of material in critical areas that seems to be the failing. It's known that Titanium bolts more susceptible to stress fracture, than steel, if not treated carefully and are not suited to applications that require frequent torque cycles. (just google titanium bolts, and you'll find a wealth of information about why they are used, and also why they are not used, depending on the application!)
Can anyone give any accurate 'guide' to just how many Gear Box pressure problems the S-92 has had since it began operating offshore, and how many of these would have resulted in a 'Land Immediately' scenario ?
There seem to be a few incidents being commented on, but I'm not sure how many of these were serious enough that they would have resulted in total lubrication loss.
There seem to be a few incidents being commented on, but I'm not sure how many of these were serious enough that they would have resulted in total lubrication loss.