Bristow S-92 Emergency landing at Yme oil platform
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150 is pretty hot and with multiple indications, is that really just Land ASAP? Evidently, from the outcome and well done to the crew but what temperature would be needed for Land Immediately and shouldn't the second oil pump be able to cope and keep the temperature down if the first fails? 
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No 150 is not that hot for the gearbox. It will tolerate a lot more. It is entirely normal and expected for the temperature to rise and to get an input hot caution with a single pump failure and the throttle in the fly position, so the other indications are all linked. Normal actions require retarding the throttle on the side of the failed pump to offload the input. It can then be set again to fly for landing. It is, as quite correctly stated a "land asap" situation, not immediately as there is no immediate danger to the aircraft. The redundancy of double pumps has done its job and maintaining normal pressure, which is the most important thing. Pressure still at 49 psi is still in the green range. It is not a land immediately unless less than 5 psi and this will not happen if one pump is still working.
The crew did entirely the correct thing and did not prolong flight for longer than necessary and landed at the nearest suitable safe landing site.
The crew did entirely the correct thing and did not prolong flight for longer than necessary and landed at the nearest suitable safe landing site.
Last edited by 26500lbs; 5th Oct 2013 at 13:38.
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There is no temp limit on its own in isolation that would require a land immediately. High MGB oil temp (above 130) will have clear cause and the temperature is a symptom of the main problem. This will be lack of pressure. High oil temp with pressure below 5 psi is a land immediately. This would be caused by a double pump failure. Single pump will not cause a large change in pressure, but is acceptable to be a low as 5 psi. Additionally the AC generators are cooled by MGB oil, so high temperatures theoretically could cause a loss of AC, so it is required to start the APU.
Complete loss of pressure cause by loss of oil would unlikely indicate a very high temp as it is measured by a wet bulb system, ie there must be oil in the gearbox for it to measure its temp.
Complete loss of pressure cause by loss of oil would unlikely indicate a very high temp as it is measured by a wet bulb system, ie there must be oil in the gearbox for it to measure its temp.
Last edited by 26500lbs; 5th Oct 2013 at 14:46.
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Loss of one MGB oil pump means that input module does not have a scavenge function. As such oil is pumped there by the other pump but it cannot go anywhere so it heats up causing the caption mentioned. After shut down the oil can return to the main module by the cross tubes and it all looks normal.
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I'm compelled to respond to Double Bogey's comment. I'm not a pilot or aircrew, just SLF. I've done it for almost 40 years though, all over the world, and he seems to understand that most of the pax just want to have a safe trip to and from work.
I'm sympathetic to the conflicts inherent in a competitive industry, especially one with safety-critical components.
The challenge, as I see it, is for the professionals here to rise above their daily delivery pressure and to see the hazards, risks and opportunities for what they are.
I don't know the answers, but I do visit this site to learn from those who might.
I'll be on Bristow out of Aberdeen Monday, and out of Stavanger the following week.
I'm placing my life, and the faith of my family, in your hands.
I'm sympathetic to the conflicts inherent in a competitive industry, especially one with safety-critical components.
The challenge, as I see it, is for the professionals here to rise above their daily delivery pressure and to see the hazards, risks and opportunities for what they are.
I don't know the answers, but I do visit this site to learn from those who might.
I'll be on Bristow out of Aberdeen Monday, and out of Stavanger the following week.
I'm placing my life, and the faith of my family, in your hands.
26,500,
I'm surprised the pressure remained at 49 psi, as the feeling was that with the -4 pumps it is much more likely to settle around 7 psi, so that in itself is interesting news. Do you know if the throttle was retarded to IDLE then re-instated for landing, or left in FLY?
I can vouch that it doesn't, but it gets pretty smelly!
I'm surprised the pressure remained at 49 psi, as the feeling was that with the -4 pumps it is much more likely to settle around 7 psi, so that in itself is interesting news. Do you know if the throttle was retarded to IDLE then re-instated for landing, or left in FLY?
Won't the metal start changing shape much above 150?
Last edited by 212man; 6th Oct 2013 at 09:12.
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Yes - I was very surprised as well to hear that the pressure remained in the green range. Certainly in the FSI sims it stabilises at 7 psi and that is in accordance with sikorsky information (and probably your experience!). I don't know if the throttle was retarded to idle or not, but I think it was a fairly short distance to Yme so probably not such an issue.
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There may well be another explantion as to why the pressure remained normal with an indication of MGB PUMP FAIL, especially if the aircraft was AMS 7.1. with auto bypass. Is it possible that the auto bypass activated erroneously thereby losing cooling of the oil?
Last edited by 26500lbs; 6th Oct 2013 at 10:05.
Not MGB oil system but an electrical problem apparently. Same happened in August in the GOM. MGB warning system CB tripped on both occasions.
Malfunction causes auto bypass to trip, rise in temp, gradual small px lower indication due hotter oil.
Malfunction causes auto bypass to trip, rise in temp, gradual small px lower indication due hotter oil.
'Industry insider'
It is interesting that this fault had been seen in another operating area yet appeared to remain a mystery to some S92 pilots on this forum.
Following the first occurrence, were the details made known to other operators and, more importantly, pilots? Surely two months is adequate time for dissemination of information that could be critical to operations.
Have we learnt nothing from our experiences with the S92 filter stud failures?
Jim
It is interesting that this fault had been seen in another operating area yet appeared to remain a mystery to some S92 pilots on this forum.
Following the first occurrence, were the details made known to other operators and, more importantly, pilots? Surely two months is adequate time for dissemination of information that could be critical to operations.
Have we learnt nothing from our experiences with the S92 filter stud failures?
Jim
Last edited by JimL; 7th Oct 2013 at 07:03.
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Jim,
It's just part of a wider problem. For over 10 years now Safety Reports disappear into the SMS to only be revealed after the Senior Management have reviewed them almost a year later. Even an MOR takes ages to resurface.
A few years back I was tasked to the Nelson. As I was leaving the Ops guy says, "Be careful there was an accident there yesterday" of course I immediately held my flight and asked for information to be told it was confidential. I then threatened to cancel my flight. Finally a Senior manager arrogantly asks "why do you want to know at your level. This is being dealt with at a much higher level"
I then explain that without knowing what happened I may well unwittingly IMMEDIATLEY repeat the incident just a day later. Only then am I told that a S61 had landed with the tail wheel in the net.
On another occasion my gear was indicating 3 greens with the selector up. We selected down and flew past the tower to be told that our gear was still firmly nesting up in the wheel bays. Followed the drill and eventually pumped it down to kneeling. No problem. However on enquiring to the ASO almost 3 months later what had caused it I was told the XMT had decided the crew had misinterpreted the indications as it was "not technically possible to have 3 greens and no gear" naturally I pursued this like a dog with a bone until finally the checklist was amended to include a visual check in such circumstances almost 1 year later.
Commercial fear and management that are either technically incompetent, dishonest or simply gutless are parts of this wider problem. This is definitely an area due for a serious review.
DB
It's just part of a wider problem. For over 10 years now Safety Reports disappear into the SMS to only be revealed after the Senior Management have reviewed them almost a year later. Even an MOR takes ages to resurface.
A few years back I was tasked to the Nelson. As I was leaving the Ops guy says, "Be careful there was an accident there yesterday" of course I immediately held my flight and asked for information to be told it was confidential. I then threatened to cancel my flight. Finally a Senior manager arrogantly asks "why do you want to know at your level. This is being dealt with at a much higher level"
I then explain that without knowing what happened I may well unwittingly IMMEDIATLEY repeat the incident just a day later. Only then am I told that a S61 had landed with the tail wheel in the net.
On another occasion my gear was indicating 3 greens with the selector up. We selected down and flew past the tower to be told that our gear was still firmly nesting up in the wheel bays. Followed the drill and eventually pumped it down to kneeling. No problem. However on enquiring to the ASO almost 3 months later what had caused it I was told the XMT had decided the crew had misinterpreted the indications as it was "not technically possible to have 3 greens and no gear" naturally I pursued this like a dog with a bone until finally the checklist was amended to include a visual check in such circumstances almost 1 year later.
Commercial fear and management that are either technically incompetent, dishonest or simply gutless are parts of this wider problem. This is definitely an area due for a serious review.
DB
It is interesting that this fault had been seen in another operating area yet appeared to remain a mystery to some S92 pilots on this forum.
Following the first occurrence, were the details made known to other operators and, more importantly, pilots? Surely two months is adequate time for dissemination of information that could be critical to operations.
Following the first occurrence, were the details made known to other operators and, more importantly, pilots? Surely two months is adequate time for dissemination of information that could be critical to operations.
Jim L
I have no idea but I agree with your sentiments. An Flight Safety Bulletin with the original occurrence information on the planning room notice board would probably have saved some **** pants.
I was informed by the operator that this was the second such occurrence. I don't know to which operator the first occurrence happened, but I believe it was on 28th August.
I have no idea but I agree with your sentiments. An Flight Safety Bulletin with the original occurrence information on the planning room notice board would probably have saved some **** pants.
I was informed by the operator that this was the second such occurrence. I don't know to which operator the first occurrence happened, but I believe it was on 28th August.
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Safety reporting & Action
Double Bogey - Very good point well made. If the authorities are serious about a safety review this is a key area they should focus on.
Systems exist for all operators that track safety reports and correcting action but as you say, reports are being 'lost', ignored or result in a friendly discussion but no action, usually due to cost implications of said action.
This has to change.
Systems exist for all operators that track safety reports and correcting action but as you say, reports are being 'lost', ignored or result in a friendly discussion but no action, usually due to cost implications of said action.
This has to change.
This is the latest informtion I have read on the situation.
On October 4th, 2013, an S-92A Helicopter operated in the North Sea experienced an electrical issue that resulted in cockpit indications of a Main Gearbox (MGB) lubrication issue. In accordance with the appropriate emergency procedures, the crew landed at the next available landing site safely with twelve passengers on board. There was no additional damage to the aircraft nor injuries to the passengers or crew.
On August 28th, 2013, an S-92A Helicopter operated in the Gulf of Mexico experienced a similar event. In that event the crew also landed safely on a platform with no damage to the aircraft nor injuries to the passengers or crew.
Both aircraft were reported to be compliant with the latest Alert Service Bulletins relating to the electrical system, MGB, and associated sensors and software.
Sikorsky is working closely with the customers to determine the cause for the indications which resulted in the precautionary landings. Information has been received from the pilots, from the on-board HUMS (Health and Usage Monitoring System) diagnostics systems, Flight Data Recorders, and from direct inspection of both aircraft.
Based on this information, it appears that in each event, a malfunction in an electrical circuit led to false advisory information to the crew, and engaged the automatic safety feature that bypasses the MGB oil cooling system. For the given conditions, the appropriate action for the crew is “land as soon as possible” in accordance with the Rotorcraft Flight Manual Emergency Procedures.
It also appears that the automatic system itself worked correctly as designed in both cases and that both MGB’s continued to operate without evidence of any damage or oil system leakage.
In both events, the main transmission warning system circuit breaker was found to be tripped. When this circuit is not functioning, the following would be expected:
· Both Left and Right MGB lubrication pump failure indications will be displayed.
MGB PUMP 1 FAIL and MGB PUMP 2 FAIL
· MGB oil pressure caution will be displayed. MGB OIL PRESS
· MGB hot caution will be displayed. MGB HOT
· Automatic feature of MGB oil system will actuate the MGB Bypass Valve, putting the system into oil cooler bypass –
· Manual Cool MAN COOL caution will be displayed but Bypass Indication MGB BYPASS will not illuminate, as it is on the same inactive circuit.
· Oil pressure may decrease immediately by 5 to 10 psi.
· Oil temperature will begin to rise.
· Oil pressure will continue to decrease slowly as temperature rises.
· No effect on the chip indication system.
Sikorsky is currently reviewing the emergency procedures to determine if any changes should be made. If any such changes are recommended, they will be transmitted immediately to all customers via Alert Service Bulletin.
Following maintenance and replacement of affected components, the first aircraft has been returned to service without further issues. The second aircraft has been recovered by replacement of affected components after which it was flown back to base without incident. This aircraft is expected to re-enter service following recommended maintenance.
Following procedure for short circuit in the M XMSN WARN system:
If the following warning lights appear:
MGB PUMP 1 FAIL and MGB PUMP 2 FAIL along with MBG OIL HOT, MGB MAN COOL, and MGB OIL and the MGB P is still positive and the MGB T is rising/ increasing – check the M XMSN circuit breaker.
Reset if popped (only one attempt allowed).
If the CB cannot be reset – Select MGB AUTO BYPASS switch to MAN COOL (Note: you will not receive a confirmation that the Valve moves to the MAN COOL position since the warning light already is illuminated)
Monitor MGB PRESS and MGB TEMP on the P and T tape on the EICAS.
Check Emergency checklist if additional warning lights appear.
On August 28th, 2013, an S-92A Helicopter operated in the Gulf of Mexico experienced a similar event. In that event the crew also landed safely on a platform with no damage to the aircraft nor injuries to the passengers or crew.
Both aircraft were reported to be compliant with the latest Alert Service Bulletins relating to the electrical system, MGB, and associated sensors and software.
Sikorsky is working closely with the customers to determine the cause for the indications which resulted in the precautionary landings. Information has been received from the pilots, from the on-board HUMS (Health and Usage Monitoring System) diagnostics systems, Flight Data Recorders, and from direct inspection of both aircraft.
Based on this information, it appears that in each event, a malfunction in an electrical circuit led to false advisory information to the crew, and engaged the automatic safety feature that bypasses the MGB oil cooling system. For the given conditions, the appropriate action for the crew is “land as soon as possible” in accordance with the Rotorcraft Flight Manual Emergency Procedures.
It also appears that the automatic system itself worked correctly as designed in both cases and that both MGB’s continued to operate without evidence of any damage or oil system leakage.
In both events, the main transmission warning system circuit breaker was found to be tripped. When this circuit is not functioning, the following would be expected:
· Both Left and Right MGB lubrication pump failure indications will be displayed.
MGB PUMP 1 FAIL and MGB PUMP 2 FAIL
· MGB oil pressure caution will be displayed. MGB OIL PRESS
· MGB hot caution will be displayed. MGB HOT
· Automatic feature of MGB oil system will actuate the MGB Bypass Valve, putting the system into oil cooler bypass –
· Manual Cool MAN COOL caution will be displayed but Bypass Indication MGB BYPASS will not illuminate, as it is on the same inactive circuit.
· Oil pressure may decrease immediately by 5 to 10 psi.
· Oil temperature will begin to rise.
· Oil pressure will continue to decrease slowly as temperature rises.
· No effect on the chip indication system.
Sikorsky is currently reviewing the emergency procedures to determine if any changes should be made. If any such changes are recommended, they will be transmitted immediately to all customers via Alert Service Bulletin.
Following maintenance and replacement of affected components, the first aircraft has been returned to service without further issues. The second aircraft has been recovered by replacement of affected components after which it was flown back to base without incident. This aircraft is expected to re-enter service following recommended maintenance.
Following procedure for short circuit in the M XMSN WARN system:
If the following warning lights appear:
MGB PUMP 1 FAIL and MGB PUMP 2 FAIL along with MBG OIL HOT, MGB MAN COOL, and MGB OIL and the MGB P is still positive and the MGB T is rising/ increasing – check the M XMSN circuit breaker.
Reset if popped (only one attempt allowed).
If the CB cannot be reset – Select MGB AUTO BYPASS switch to MAN COOL (Note: you will not receive a confirmation that the Valve moves to the MAN COOL position since the warning light already is illuminated)
Monitor MGB PRESS and MGB TEMP on the P and T tape on the EICAS.
Check Emergency checklist if additional warning lights appear.
Last edited by SASless; 7th Oct 2013 at 13:42.
I find this a bizarre failure mode, and I'm particularly disturbed to see that the MAN COOL caption is displayed despite the reverse being true!
Based on this information, it appears that in each event, a malfunction in an electrical circuit led to false advisory information to the crew, and engaged the automatic safety feature that bypasses the MGB oil cooling system.
Won't the metal start changing shape much above 150?
Which metal, by the way?
There are multiple materials in a helicopter gearbox.
Last edited by Lonewolf_50; 8th Oct 2013 at 14:17.
Shawn,
In the 225 events we saw the Emergency Cooling system operate correctly but give a bogus "Fail" indication.
When one compares the 92 and 225 events it makes one wonder if the aircraft have gotten too complex and perhaps a step back in automation might be considered.
A similar example is the S-76 Rotor Brake system as compared to the simple old fashioned Hand Lever operated Rotor Brake.
Are we making trouble for ourselves in trying to automate what should be better left in older more dependable levels of sophistication?
In the 225 events we saw the Emergency Cooling system operate correctly but give a bogus "Fail" indication.
When one compares the 92 and 225 events it makes one wonder if the aircraft have gotten too complex and perhaps a step back in automation might be considered.
A similar example is the S-76 Rotor Brake system as compared to the simple old fashioned Hand Lever operated Rotor Brake.
Are we making trouble for ourselves in trying to automate what should be better left in older more dependable levels of sophistication?