Helicopter crash off the coast of Newfoundland - 18 aboard, March 2009
Squibb....it was an honest question and thank you for your response.
What I get from your answer is there is no way to know with certainty there has been a complete/near complete loss of oil and the only suggestion would be a decrease or loss of pressure which could also be due to other causes or even bogus indications.
Is that a correct assumption?
Way back during this thread I also suggested temperature sensing also relied upon having oil to accurately reflect the actual oil temperature and upon a loss of oil it would be possible to lose reliable temp indications.
As I see it....without knowing there has been a loss of oil, one would not know when to start the 30 minute countdown timer.
Am I missing something in looking at the way the oil quantity can be ascertained in flight by the pilots?
I used to have a valid 92 Checklist but lost it in a hard drive death so I cannot look back on that to refresh my recollection.
What I get from your answer is there is no way to know with certainty there has been a complete/near complete loss of oil and the only suggestion would be a decrease or loss of pressure which could also be due to other causes or even bogus indications.
Is that a correct assumption?
Way back during this thread I also suggested temperature sensing also relied upon having oil to accurately reflect the actual oil temperature and upon a loss of oil it would be possible to lose reliable temp indications.
As I see it....without knowing there has been a loss of oil, one would not know when to start the 30 minute countdown timer.
Am I missing something in looking at the way the oil quantity can be ascertained in flight by the pilots?
I used to have a valid 92 Checklist but lost it in a hard drive death so I cannot look back on that to refresh my recollection.
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SASless
I'm glad I did give a flippant answer like 'when the tail rotor power is lost' then!
Yes oil temperature would become unreliable and certainly would not rise as the gears got hot if oil was not flowing over it.
Ah but in the certification loss of lubrication test, the timing starts when the low oil pressure light illuminates (which depending on the setting may mean 30-50% of the oil has already been lost).
It is also worth remembering that in the test Sikorsky used to show compliance with that requirement, as well as making the assumption that the oil loss was most likely to be from the oil cooler, they also made the assumption that the crew would manually activate the oil cooler bypass in less than 10 seconds from that low pressure light being illuminated (now that is an immediate action!).
There is a checklist in this thread that HC first posted after one of the earlier oil system incidents http://www.pprune.org/6036981-post688.html
I'm glad I did give a flippant answer like 'when the tail rotor power is lost' then!
Yes oil temperature would become unreliable and certainly would not rise as the gears got hot if oil was not flowing over it.
As I see it....without knowing there has been a loss of oil, one would not know when to start the 30 minute countdown timer.
It is also worth remembering that in the test Sikorsky used to show compliance with that requirement, as well as making the assumption that the oil loss was most likely to be from the oil cooler, they also made the assumption that the crew would manually activate the oil cooler bypass in less than 10 seconds from that low pressure light being illuminated (now that is an immediate action!).
There is a checklist in this thread that HC first posted after one of the earlier oil system incidents http://www.pprune.org/6036981-post688.html
So....I reach up and flip said switch in the Ten Second interval required and am left assuming I have trapped some residual oil. After doing that.....would I be able to identify a continuing leak of oil and determine I need do something more drastic than I have done so far in the process?
Much earlier I posed a question about whether the displayed oil temp might even DECREASE rather than increase if there was a complete/near complete loss of oil.
Any thoughts along these lines?
Much earlier I posed a question about whether the displayed oil temp might even DECREASE rather than increase if there was a complete/near complete loss of oil.
Any thoughts along these lines?
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Having rechecked the FM you have just 5s to activate the bypass in fact!
Only by a falling oil pressure BUT confusingly that is also a symptom of oil pump failures unrelated to oil loss that had happened 3 times prior (at least).
At the time of the Norsk incident any continuing pressure drop below 35psi was meant to trigger a pilot action to Land Immediately. Sometime after that it was relaxed to a continued drop below just 5spi.
I think oil temp would at best be 'unreliable' and certainly might go down if the sensor is not 'washed' by hot oil. The Flight Manual does however discuss high oil temperatures at a warning sign - something that might cause more confusion to a crew turning for shore and assessing the situation.
Hopefully the TSB have considered all this in detail. Its just a pity they did not push the issue of the MGB design after they looked at the filter housing from CHC Australia's aircraft (though ATSB did not investigate that one either).
The TSB report is out at 17:30UTC.
would I be able to identify a continuing leak of oil and determine I need do something more drastic than I have done so far in the process?
At the time of the Norsk incident any continuing pressure drop below 35psi was meant to trigger a pilot action to Land Immediately. Sometime after that it was relaxed to a continued drop below just 5spi.
Much earlier I posed a question about whether the displayed oil temp might even DECREASE rather than increase if there was a complete/near complete loss of oil.
Hopefully the TSB have considered all this in detail. Its just a pity they did not push the issue of the MGB design after they looked at the filter housing from CHC Australia's aircraft (though ATSB did not investigate that one either).
The TSB report is out at 17:30UTC.
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From a quick first pass of the report main issues IMO:
PIC did not believe that MRGB lube oil was gone due to false "normal" temperature indication. Pump failure was suspect as cause of no lube oil pressure. But temperature should have increased with activation of bypass switch which was done very late. This was a key miss by the PIC IMO.
Only when T/R drive failed did they know for sure.
Sad, very very sad...here's hoping the TSB recommended changes make this scenario a thing of the past.
Safe flying
Max
PIC did not believe that MRGB lube oil was gone due to false "normal" temperature indication. Pump failure was suspect as cause of no lube oil pressure. But temperature should have increased with activation of bypass switch which was done very late. This was a key miss by the PIC IMO.
Only when T/R drive failed did they know for sure.
Sad, very very sad...here's hoping the TSB recommended changes make this scenario a thing of the past.
Safe flying
Max
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Wow - that is a report. If they can get these sort of recommendations sorted in agreement with the FAA and EASA it will be very interesting.
I imagine that there would be a lot of days with no flying.
TSB Recommendations
The Federal Aviation Administration, Transport Canada and the European Aviation Safety Agency remove the "extremely remote" provision from the rule requiring 30 minutes of safe operation following the loss of main gearbox lubricant for all newly constructed Category A transport helicopters and, after a phase-in period, for all existing ones.
The Federal Aviation Administration assess the adequacy of the 30 minute main gearbox run dry requirement for Category A transport helicopters.
Transport Canada prohibit commercial operation of Category A transport helicopters over water when the sea state will not permit safe ditching and successful evacuation.
Transport Canada require that supplemental underwater breathing apparatus be mandatory for all occupants of helicopters involved in overwater flights who are required to wear a Passenger Transportation Suit System.
The Federal Aviation Administration, Transport Canada and the European Aviation Safety Agency remove the "extremely remote" provision from the rule requiring 30 minutes of safe operation following the loss of main gearbox lubricant for all newly constructed Category A transport helicopters and, after a phase-in period, for all existing ones.
The Federal Aviation Administration assess the adequacy of the 30 minute main gearbox run dry requirement for Category A transport helicopters.
Transport Canada prohibit commercial operation of Category A transport helicopters over water when the sea state will not permit safe ditching and successful evacuation.
Transport Canada require that supplemental underwater breathing apparatus be mandatory for all occupants of helicopters involved in overwater flights who are required to wear a Passenger Transportation Suit System.
This seems to be the most telling statement
Therefore, the Board recommends that:
The Federal Aviation Administration, Transport Canada and the European Aviation Safety Agency remove the "extremely remote" provision from the rule requiring 30 minutes of safe operation following the loss of main gearbox lubricant for all newly constructed Category A transport helicopters and, after a phase-in period, for all existing ones.
A11-01
The Federal Aviation Administration, Transport Canada and the European Aviation Safety Agency remove the "extremely remote" provision from the rule requiring 30 minutes of safe operation following the loss of main gearbox lubricant for all newly constructed Category A transport helicopters and, after a phase-in period, for all existing ones.
A11-01
Thanks for the link CR. Still digesting it but it seems to be an excellent report, though it does make rather depressing reading in a number of areas. PPRuNe gets a mention, which is perhaps a first in an accident report?
HC
HC
On 06 August 2002, Sikorsky carried out its initial certification loss of lubricant test by draining the MGB and using only the remaining residual oil (approximately 1.3 gallons) then continuing operation in accordance with the requirements of AC 29-2C.136 The purpose of this test, outlined in the test documentation, was to demonstrate that the S-92A transmission could provide, "continued safe operation for a minimum of 30 minutes following a complete loss of lubricating oil in accordance with the requirements of FAR 29.927(c)(1)."
The MGB suffered a catastrophic failure about 11 minutes after the test was started. The root cause for the loss of drive was determined to be the complete loss of teeth from the sun gear due to excessive temperature caused by lack of lubrication.
The MGB suffered a catastrophic failure about 11 minutes after the test was started. The root cause for the loss of drive was determined to be the complete loss of teeth from the sun gear due to excessive temperature caused by lack of lubrication.
Well there you have it. That was always the big secret, was it not?
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I watched the press conference. They certainly didn't pull any punches there either. I was disappointed that the talking head started yapping just after the floor was opened for questions.
Transport Canada require that supplemental underwater breathing apparatus be mandatory for all occupants of helicopters involved in overwater flights who are required to wear a Passenger Transportation Suit System.
Mickjoebill
The explanation is in the report. The connection is how long a person can hold their breath depending on the temperature of the water. If the water is cold enough to require an immersion suit, the conclusion is that they won't be able to hold their breath long enough to exit the aircraft. Hence if the water temp dictates that a suit is required, then an EUBA is logically required as well. Note the water temps were about 0C that day.
I don't think you have to worry about it in Oz with the warm water there.
I don't think you have to worry about it in Oz with the warm water there.
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At 1037, Cougar Rescue 61, a company S-92A equipped for search and rescue (SAR) operations, departed CYYT for the accident site, arriving at 1055. Using the helicopter's hoist, a rescue specialist recovered the sole survivor approximately 20 minutes later.
but why 20 minutes after arrival? When someone is in freezing cold water, should you not be getting him out ASAP, injuries or no injuries?