Sikorsky S-92: From Design to Operations
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he1iaviator
The 139 as said before passed the 30 minute test and exceeded the requirements. Good design and commitment to provide an as advertised product may have had an influence. No additional smart add on stuff to assist, the basic stuff is good enough.
As I hope all would expect NO mention of any run dry time in the emergency check list or advisories.
The 139 as said before passed the 30 minute test and exceeded the requirements. Good design and commitment to provide an as advertised product may have had an influence. No additional smart add on stuff to assist, the basic stuff is good enough.
As I hope all would expect NO mention of any run dry time in the emergency check list or advisories.
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The question may need to be asked at some point, when SK did the test! What was the timeline that they came to regarding operation with accelerated fluid loss to 0 psi and mechanical failings? The answer must be a matter of internal record.
Last edited by outhouse; 27th Mar 2009 at 08:41.
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Phugs,
I am astonished at your complacent attitude to this accident.
Human factor are implicated in (probably) more than 75% of accidents; if it is known that a material/product/procedure is not tolerant to human practices/intervention, it must be engineered out.
The S92 is not doing 'pretty well' it has a history of gearbox events including a carbon copy of this event in Broome last year - perhaps it is the lack of an expeditious response to that incident which might now be called into question. Were regulators/operators aware of the criticality of that incident for an aircraft that spends most of its time over hostile areas? Did SAC/FAA allow too much leeway for compliance?
There has been substantial prevarication about the ability of the gearbox to meet the FAR 29.927 standard. Are we entitled to know about lack of compliance? Did this feature in the crew's decision to turn back to fly to land rather than land immediately?
Contributors to this board also have to bear some responsibility; how many times (even recently) have we heard a call to 'interpret' the check list. Only from FH1100 (a pity he/she has now been banned) have we heard an unequivocal call to comply with the procedure.
Don't post just to get your name on the Internet - think about what you are saying.
I am astonished at your complacent attitude to this accident.
Human factor are implicated in (probably) more than 75% of accidents; if it is known that a material/product/procedure is not tolerant to human practices/intervention, it must be engineered out.
The S92 is not doing 'pretty well' it has a history of gearbox events including a carbon copy of this event in Broome last year - perhaps it is the lack of an expeditious response to that incident which might now be called into question. Were regulators/operators aware of the criticality of that incident for an aircraft that spends most of its time over hostile areas? Did SAC/FAA allow too much leeway for compliance?
There has been substantial prevarication about the ability of the gearbox to meet the FAR 29.927 standard. Are we entitled to know about lack of compliance? Did this feature in the crew's decision to turn back to fly to land rather than land immediately?
Contributors to this board also have to bear some responsibility; how many times (even recently) have we heard a call to 'interpret' the check list. Only from FH1100 (a pity he/she has now been banned) have we heard an unequivocal call to comply with the procedure.
Don't post just to get your name on the Internet - think about what you are saying.
Phug - it is exactly because we may end up flying it in the future that there is so much noise being made now - why on earth would you want to keep quiet about something that is clearly a design problem and hamstrings an otherwise very capable helicopter?
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In the 225 forum on 31 July 2004 a question was asked of someone close to the S92 programme :
The answer:
No comment!
Please can you confirm whether or not the S92 also has a true 30 minute run dry gearbox as I'm unclear on this? Is immediate pilot action required in the event of a loss of main gearbox pressure? Does the check-list say "Land Immediately"?
And the S-92's oil protection system protected the transmission to the FAR/JAR with such aplomb that we shut the test down at 3 hours, not 30 minutes, with the system still running along (but admittedly pretty close to its end). That is 2 1/2 hours longer than required. The pilot must activate the system, but has several seconds to do so after clear indications, and the checklist does not say "land immediately."
As that answer suggests " the S-92's oil protection system protected the transmission .......... "
It is referring to the S-92's only Oil Protection system. A basic cooler bypass system - And yes, I would expect that to work for quite a while. Sikorski have managed to mis-market their Gear Box safety system so effectively that even pilots flying the 92 seem to be under the misapprehension that it will run dry for at least 30 mins.
At least there is an 'honesty' with the 332 that you know you are in the water if you lose Gear Box Pressure. The 225 it seems states 30 mins if the Emergency Lubrication is running, but that may be enough to get you down or to a safer place to land.
I am shocked at how quickly this Gear Box lost pressure, but I think if you accept the worst case, the cork pulled from the sump of the Gear Box, knowing there is not reserve or dry running, who would now be flying them around at 9,000 ft ?
It is referring to the S-92's only Oil Protection system. A basic cooler bypass system - And yes, I would expect that to work for quite a while. Sikorski have managed to mis-market their Gear Box safety system so effectively that even pilots flying the 92 seem to be under the misapprehension that it will run dry for at least 30 mins.
At least there is an 'honesty' with the 332 that you know you are in the water if you lose Gear Box Pressure. The 225 it seems states 30 mins if the Emergency Lubrication is running, but that may be enough to get you down or to a safer place to land.
I am shocked at how quickly this Gear Box lost pressure, but I think if you accept the worst case, the cork pulled from the sump of the Gear Box, knowing there is not reserve or dry running, who would now be flying them around at 9,000 ft ?
212Man,
Thank you for the details on the CV/FDR and the generator arrangement.
The regulatory agencies frown on "g" switches and promote using parameter driven logic like rotor rpm and oil pressures to provide the shutdown logic. I was wondering if the 92 may have used a combination of these type of indications which might have allowed the sequence of events to meet the logic and command the recorder to shut down. Since they have a "g" switch, the logic based approach would not be needed.
HC,
The recorders stopped 1 minute before the call that they were ditching. I doubt anything occurred at this time which could have tripped the "G" switch.
The Sultan
Thank you for the details on the CV/FDR and the generator arrangement.
The regulatory agencies frown on "g" switches and promote using parameter driven logic like rotor rpm and oil pressures to provide the shutdown logic. I was wondering if the 92 may have used a combination of these type of indications which might have allowed the sequence of events to meet the logic and command the recorder to shut down. Since they have a "g" switch, the logic based approach would not be needed.
HC,
The recorders stopped 1 minute before the call that they were ditching. I doubt anything occurred at this time which could have tripped the "G" switch.
The Sultan
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S92 Demonstrated Dry Run Capability
I invite you to read the timeline below, and judge for yourself the dry run capability of this particular S92 and the crews understanding of how much time was available.
Chronology of events: offshore helicopter Cougar Flight 491
Last Updated: Thursday, March 26, 2009 | 5:54 PM NT Comments7Recommend12
CBC News
This draft chronology of events has been compiled from information provided by the Transportation Safety Board of Canada.
Times are in Universal Time Co-ordinated , or UTC, (roughly equivalent to Greenwich Mean Time).
11:48:07 Cougar Flight CHI91 departs St. John's.
12:05:52 CHI91 advises Gander Area Control Centre (ACC) that they have levelled off at 9,000 feet and that their estimated time of arrival at the Hibernia platform is 13:10. Speed is 110 knots.
12:15:05 Rapid loss of main gearbox oil pressure occurs. No abnormal indications of any kind recorded on flight data recorder prior to this event.
12:15:19 CHI91 begins a right turn.
12:15:24 Main gearbox oil pressure decreases to approximately five psi.
12:15:27 CHI91 issues mayday call to Gander ACC and begins descent from 9,000 feet. They are 53 nautical miles from St. John's.
12:15:32 CHI91 advises Gander ACC that they have main gearbox oil pressure problems and requests immediate clearance to return to St. John's.
12:15:43 CHI91 heads back to the coast. Their heading is 290 degrees and their speed is 120 knots.
12:17:04 Main gearbox oil pressure reaches 0 psi.
12:17:25 CHI91 advises Gander ACC that they are heading for nearest land. Their heading is 292 degrees and their speed is 122 knots.
12:17:42 CHI advises Gander ACC that they have lost all main gearbox oil pressure. CHI91 is descending through an altitude of 5,740 feet.
12:18:25 Gander ACC advises CHI91 that they are 42 miles from Cape Spear.
12:19:10 Gander ACC advises CHI91 that search and rescue has been notified.
12:19:18 CHI91 advises Gander ACC that Cougar dispatch has been advised and that another helicopter is being readied.
12:22:20 CHI91 levels off at approximately 800 feet. Their heading is 292 degrees and their speed is 133 knots.
12:24:44 A power interruption to the Flight Data Recorder/Cockpit Voice Recorder occurs.
12:25:36 CHI91 advises Gander ACC that they are preparing to ditch.
12:25:52 St. John's radar records CHI91 at 800 feet. CHI91 subsequently descends to 300 feet in approximately 29 seconds which equates to an approximate rate of descent of 1,000 feet per minute.
12:26:26 St. John's radar records the last radar return of CHI91 at 300 feet.
12:26 Gander ACC advises search and rescue that CHI91 has ditched. Cougar dispatch confirms the ditching with search and rescue, and advises that they will launch Cougar 61 as a rescue helicopter.
12:42 A Provincial Airlines patrol aircraft arrives at crash site and observes two people in orange immersion suits in the water.
13:07 Cougar rescue helicopter departs St. John's.
13:25 Cougar rescue helicopter arrives at crash site and spots two people (one of whom is later confirmed dead), two rafts and helicopter debris.
13:33 Cougar rescue helicopter lowers a rescue person toward the people in the water.
Chronology of events: offshore helicopter Cougar Flight 491
Last Updated: Thursday, March 26, 2009 | 5:54 PM NT Comments7Recommend12
CBC News
This draft chronology of events has been compiled from information provided by the Transportation Safety Board of Canada.
Times are in Universal Time Co-ordinated , or UTC, (roughly equivalent to Greenwich Mean Time).
11:48:07 Cougar Flight CHI91 departs St. John's.
12:05:52 CHI91 advises Gander Area Control Centre (ACC) that they have levelled off at 9,000 feet and that their estimated time of arrival at the Hibernia platform is 13:10. Speed is 110 knots.
12:15:05 Rapid loss of main gearbox oil pressure occurs. No abnormal indications of any kind recorded on flight data recorder prior to this event.
12:15:19 CHI91 begins a right turn.
12:15:24 Main gearbox oil pressure decreases to approximately five psi.
12:15:27 CHI91 issues mayday call to Gander ACC and begins descent from 9,000 feet. They are 53 nautical miles from St. John's.
12:15:32 CHI91 advises Gander ACC that they have main gearbox oil pressure problems and requests immediate clearance to return to St. John's.
12:15:43 CHI91 heads back to the coast. Their heading is 290 degrees and their speed is 120 knots.
12:17:04 Main gearbox oil pressure reaches 0 psi.
12:17:25 CHI91 advises Gander ACC that they are heading for nearest land. Their heading is 292 degrees and their speed is 122 knots.
12:17:42 CHI advises Gander ACC that they have lost all main gearbox oil pressure. CHI91 is descending through an altitude of 5,740 feet.
12:18:25 Gander ACC advises CHI91 that they are 42 miles from Cape Spear.
12:19:10 Gander ACC advises CHI91 that search and rescue has been notified.
12:19:18 CHI91 advises Gander ACC that Cougar dispatch has been advised and that another helicopter is being readied.
12:22:20 CHI91 levels off at approximately 800 feet. Their heading is 292 degrees and their speed is 133 knots.
12:24:44 A power interruption to the Flight Data Recorder/Cockpit Voice Recorder occurs.
12:25:36 CHI91 advises Gander ACC that they are preparing to ditch.
12:25:52 St. John's radar records CHI91 at 800 feet. CHI91 subsequently descends to 300 feet in approximately 29 seconds which equates to an approximate rate of descent of 1,000 feet per minute.
12:26:26 St. John's radar records the last radar return of CHI91 at 300 feet.
12:26 Gander ACC advises search and rescue that CHI91 has ditched. Cougar dispatch confirms the ditching with search and rescue, and advises that they will launch Cougar 61 as a rescue helicopter.
12:42 A Provincial Airlines patrol aircraft arrives at crash site and observes two people in orange immersion suits in the water.
13:07 Cougar rescue helicopter departs St. John's.
13:25 Cougar rescue helicopter arrives at crash site and spots two people (one of whom is later confirmed dead), two rafts and helicopter debris.
13:33 Cougar rescue helicopter lowers a rescue person toward the people in the water.
The recorders stopped 1 minute before the call that they were ditching. I doubt anything occurred at this time which could have tripped the "G" switch.
Can we safely assume such a Generator failure would have been caused either by over heating due to oil loss? If they made a ditching call a minute or so after the Generator loss then it would rule out a catastrophic MGB failure that caused the Generators to fail I would think.
Can we safely assume such a Generator failure would have been caused either by over heating due to oil loss
Radio Call Implication
SASless, the Copilot VHF was always on the Battery Bus, so that call by itself wouldn't necessarily confirm/deny anything about Main AC Gen condition, nor whether they had started the APU .
Thanks,
John Dixson
Thanks,
John Dixson
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One problem with making statements and commenting on PPR is that one can always go back and view. The S92 MGB certification question seemed to spread onto the EC225 thread in 2004. Certain statements made at the time seem to indicate compliance to FAA and JAA requirements’.
Sorry but I feel It would be helpful if the author of those statements could re visit this thread to explain statements made and origin behind them.
O
Sorry but I feel It would be helpful if the author of those statements could re visit this thread to explain statements made and origin behind them.
O
Last edited by outhouse; 27th Mar 2009 at 18:04. Reason: add to request.
Outhouse
In the absence of horse's mouth, I should point out that (at least latterly, when pressed on the point and after the trite but meaningless responses) I don't think he ever said the 92 had 30 mins dry running time. He did say it complied with 29.927 and of course the FAA agree with him. The fundamental problem is a weak regulation whose first words are the get-out clause, and a regulatory authority who are quite happy to endorse the useage of the loophole.
HC
In the absence of horse's mouth, I should point out that (at least latterly, when pressed on the point and after the trite but meaningless responses) I don't think he ever said the 92 had 30 mins dry running time. He did say it complied with 29.927 and of course the FAA agree with him. The fundamental problem is a weak regulation whose first words are the get-out clause, and a regulatory authority who are quite happy to endorse the useage of the loophole.
HC
Last edited by HeliComparator; 28th Mar 2009 at 12:22. Reason: Correcting JAR reference
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Far29.927
I think the inference of the quote in #1445 above is that at some point there was testing carried out in order to meet the FAR29.927 requirements (i.e. the escape clause was not used) - if that was indeed the case some of the wording used is very pertinent to some recent thread discussion :
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 flightcrew of the lubrication system failure or loss of lubricant.
Of course there may have been subsequent testing, or the escape clause may subsequently have in fact been used.
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 flightcrew of the lubrication system failure or loss of lubricant.
Of course there may have been subsequent testing, or the escape clause may subsequently have in fact been used.
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One step back
I guess Sikorsky once had the right stuff in their machines. This out of the UH-60 "little brother" of the 92 aircrew manual.
The intermediate gear box may run at cruise flight for 30 minutes, with loss of all oil.
The tail gear box may run at cruise flight for 30 minutes with loss of all oil.
I still think it is more of a "get over on the right side of the fence" capability, not intended for extended overwater flights.
The emergency procedure states
MAIN XMSN OIL PRESS Caution Appears/
One gets the impression that still time is of the essence! ("If time permits")
The UH-60 can still be controlled by use of the electric back-up hydraulic pump, powered by the APU, even if both the transmission mounted pumps give up. As far as I have been told this is not the case with the 92. The electric hydraulic pump is only for ground checking of the flightcontrols, and inhibited in flight by the weight on wheels micro switch. Maybe a modification to this system might be in order, to have a last attemt at a semicontrolled ditch.
Torcher
The lubrication
system includes two lubrication pumps that are combination
pressure and scavenge types operating in parallel. The
main transmission may run at cruise flight for 30 minutes
with loss of all oil.The intermediate gear box may run at cruise flight for 30 minutes, with loss of all oil.
The tail gear box may run at cruise flight for 30 minutes with loss of all oil.
I still think it is more of a "get over on the right side of the fence" capability, not intended for extended overwater flights.
The emergency procedure states
MAIN XMSN OIL PRESS Caution Appears/
XMSN OIL PRESS LOW/XMSN OIL TEMP HIGH or
XMSN OIL TEMP Caution Appears. Loss of cooling
oil supply will lead to electrical and/or mechanical failure
of main generators. If the malfunction is such that oil
pressure decays slowly, the generators may fail before
MAIN XMSN OIL PRESS caution appears.
1. LAND AS SOON AS POSSIBLE.
If time permits:
2. Slow to 80 KIAS.
3. EMER APU START.
4. GENERATORS NO. 1 and NO. 2 switches -OFFOne gets the impression that still time is of the essence! ("If time permits")
The UH-60 can still be controlled by use of the electric back-up hydraulic pump, powered by the APU, even if both the transmission mounted pumps give up. As far as I have been told this is not the case with the 92. The electric hydraulic pump is only for ground checking of the flightcontrols, and inhibited in flight by the weight on wheels micro switch. Maybe a modification to this system might be in order, to have a last attemt at a semicontrolled ditch.
Torcher
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If MGB pressure drops below 5 psi it is LAND IMMEDIATE.
Which is strange as Nicklappos stated on 31 July 2004:
http://www.pprune.org/rotorheads/191...ml#post1454917
and
http://www.pprune.org/rotorheads/191...ml#post1455317
Looks to me Sikorsky never did an oil out test, just closed off the oil cooler and ran with hot oil and ignored loss of oil from elsewhere, inspiring unwarrented confidence.
Which is strange as Nicklappos stated on 31 July 2004:
http://www.pprune.org/rotorheads/191...ml#post1454917
And the S-92's oil protection system protected the transmission to the FAR/JAR with such aplomb that we shut the test down at 3 hours, not 30 minutes, with the system still running along (but admittedly pretty close to its end). That is 2 1/2 hours longer than required. The pilot must activate the system, but has several seconds to do so after clear indications, and the checklist does not say "land immediately."
http://www.pprune.org/rotorheads/191...ml#post1455317
vertalop,
The oil system, and the entire aircraft, meet FAR/JAR ammendment 47 (the latest). The FAA sat next to us as the transmission ran those 3 hours!
look for a private message, with some additional thoughts.
best,
Nick
The oil system, and the entire aircraft, meet FAR/JAR ammendment 47 (the latest). The FAA sat next to us as the transmission ran those 3 hours!
look for a private message, with some additional thoughts.
best,
Nick
Last edited by Shell Management; 28th Mar 2009 at 10:10.
Torcher,
Not trying to be picky here but in the RFM definitions....what is "May" defined as meaning? Generally it is permissive in application.
In real language it means something really different such as meaning "may yes....may not!
I guess the Sixty Four Dollar question that Sikorsky and the FAA are going to have to answer is "Did they run a MGB with a complete loss of lubricant in the presence of the FAA?"
Not trying to be picky here but in the RFM definitions....what is "May" defined as meaning? Generally it is permissive in application.
In real language it means something really different such as meaning "may yes....may not!
I guess the Sixty Four Dollar question that Sikorsky and the FAA are going to have to answer is "Did they run a MGB with a complete loss of lubricant in the presence of the FAA?"