North Sea heli ditching: Oct 2012
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Oddly enough I was having just this conversation with a crew on their way into Norwich last night, and, co-incidentally, they'd also just finished said discussion when I butted in and interrupted their consumption of snack - a - jacks.
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Some crashes have more profound after effects than others, and I suspect this is one of those.
Which crash are you talking about ?
In contrast, the S76A+ that crashed out of Norwich 10 years ago was seen as an exceptional accident, due to having had a lightning strike on the blade in the past. Engineering inspections were carried out and procedures changed, and the aircraft returned to service. S76's are still flying on the North Sea (including now 2 in Aberdeen covering from this latest incident).
Whoever decided to sell off all the Bristow 61's is probably wishing he had remembered the Old Man's practice of shoving surplus machines over into the corner just in case of a rainy day or a golden opportunity presenting itself.
Ah yes.....the "Manager's Bonus" and Quarterly Report....which now drives all thinking. When we use a 90 day window for planning....and pay manager's bonuses for squeezing every last penny from an Operation we foster some very short sightedness don't we! Almost like some Nigerian Grocery Stores I remember!
Last edited by SASless; 2nd Nov 2012 at 10:41.
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My guess is the old man stuffed them over in the corner because there were no available buyers not because some unforseen incident 5 years hence might require them.
There is the matter of cost. A certain amount of hull insurance may be neccessary. Do you pull them out peridically and exercise them or just let them sit? If you exercise them - another expense. How about crew training? Do you keep crews current or just try and get them up to speed when the aircraft are pulled out of mothballs?
Remember in business you spend a dollar (or euro or pound) and hope to earn say $1.10-1.25 in return. You save a dollar and you just earned a dollar.
There is the matter of cost. A certain amount of hull insurance may be neccessary. Do you pull them out peridically and exercise them or just let them sit? If you exercise them - another expense. How about crew training? Do you keep crews current or just try and get them up to speed when the aircraft are pulled out of mothballs?
Remember in business you spend a dollar (or euro or pound) and hope to earn say $1.10-1.25 in return. You save a dollar and you just earned a dollar.
Failure Modes on the test stand.
The 225 EMLUBE system was, I believe, designed only to deal with a loss of transmission oil not the loss of 2 oil pumps.
In these 2 cases there was not a loss of fluid but an internal failure of the shaft.
So my question is this:
Would proper indication of functioning of the EMLUBE system in this scenario have allowed the safe continuation of flight for the "sacred" 30 minutes (29 minutes 59 seconds as one friend defines it) or would there have been a catastrophic failure of the transmission shaft beforehand?
There would be no way for the crew to differentiate between the two failure modes - except perhaps increasing vibration levels in the event of further shaft failure. With no oil flow through the system there would be no chip detection to advise of things going pear shaped.
I am also told that with dual pump failure and no oil loss from the transmission that the EMLUBE system injecting glycol into an already "full" transmission would cause overflow of a mixture of glycol and oil from the transmission vent which would flow around the transmission area and perhaps even down into the passenger compartment. Would this venting cause a fire hazard?
It would be interesting to see if EC is going to test the transmission and EMLUBE system with this failure model and a fully set up system (alternators producing power ect.) on the test stand.
Edited to add a thought: Since the transmission is still full of oil or an oil/glycol mix would the crew still have an accurate transmission temperature? Don't have my 225 manuals close to hand unfortunately.
In these 2 cases there was not a loss of fluid but an internal failure of the shaft.
So my question is this:
Would proper indication of functioning of the EMLUBE system in this scenario have allowed the safe continuation of flight for the "sacred" 30 minutes (29 minutes 59 seconds as one friend defines it) or would there have been a catastrophic failure of the transmission shaft beforehand?
There would be no way for the crew to differentiate between the two failure modes - except perhaps increasing vibration levels in the event of further shaft failure. With no oil flow through the system there would be no chip detection to advise of things going pear shaped.
I am also told that with dual pump failure and no oil loss from the transmission that the EMLUBE system injecting glycol into an already "full" transmission would cause overflow of a mixture of glycol and oil from the transmission vent which would flow around the transmission area and perhaps even down into the passenger compartment. Would this venting cause a fire hazard?
It would be interesting to see if EC is going to test the transmission and EMLUBE system with this failure model and a fully set up system (alternators producing power ect.) on the test stand.
Edited to add a thought: Since the transmission is still full of oil or an oil/glycol mix would the crew still have an accurate transmission temperature? Don't have my 225 manuals close to hand unfortunately.
Last edited by albatross; 2nd Nov 2012 at 19:44.
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I see what you are getting at with regards to the mix of oil and glycol, however, the glycol isn't pumped in as such and is actually mixed with the P2.4 air from #1 engine and sprayed onto the hottest parts of the box. I think I'm correct in saying it sprays periodically rather than dump it all in one shot. Also, the actual volume of glycol isn't that much (can't recall exact volume) and as such, I don't think venting out the box would be too much of an issue especially when 1. I'd hope the crew would be landing sooner rather than later and 2. The box vents to the aft of the mgb area and would run along outside of sliding cowl
One must wonder how much lubrication there is with a tranmission case full of oil and inoperative pumps. The input pinion and bevel gear would be totally immersed going around at a cosiderable rate. Gears have rough edges so it would be like a big high speed food processor inside the gearbox. How much would this activity lubricate the reduction gears and more importantly, how much oil mist for the top bearing? Obviously in a fairly short time the oil would start to overheat but how long is a fairly short time?
The Newfoundland S92 ran out of oil. The Puma Mk2 had a component failure internally, the first for 4 million hours. Both the 225s ditched with no apparant complaint from the gearbox apart from warning lights. All the trials so far have assumed the gearbox to be dry. Have they tried to run one without oil pressure to see what its running time is? It could be a nice surprise, there are enough gearboxs in this world that do not have the luxury of an oil pump.
The biggest problem is working out whether you have lost your oil or your oil pump, that is for somebody else to sort out.
The Newfoundland S92 ran out of oil. The Puma Mk2 had a component failure internally, the first for 4 million hours. Both the 225s ditched with no apparant complaint from the gearbox apart from warning lights. All the trials so far have assumed the gearbox to be dry. Have they tried to run one without oil pressure to see what its running time is? It could be a nice surprise, there are enough gearboxs in this world that do not have the luxury of an oil pump.
The biggest problem is working out whether you have lost your oil or your oil pump, that is for somebody else to sort out.
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EMLUB
@albatross: Not sure I am following you on the "The 225 EMLUBE system was, I believe, designed only to deal with a loss of transmission oil not the loss of 2 oil pumps."
The 225 EMLUB system was precisely designed to cope with a complete loss of lubrication, i.e. failure of both Main & Standby pumps.
Proper indication of a functioning EMLUB as you call it would be the absence of any light - Black Panel - And yes according to the Manufacturers ECL "Land as soon as possible - Maximum flight time 30 minutes"
About your edited thought: Again not sure what you mean by "would the crew still have an accurate transmission temperature?" since the Oil temperature switch sits at the bottom of the MGB case, immersed in oil and measuring the oil temperature. Remember the S-92 Cougar crash report, the crew expected an increase in oil temperature associated with a loss of oil, which led the pilots to incorrectly rely on MGB oil temperature as a secondary indication of an impending MGB failure. So regardless of your oil temperature being below 128 degrees following a failure of the EMLUB system, the ECL states explicitly what to do.
The 225 EMLUB system was precisely designed to cope with a complete loss of lubrication, i.e. failure of both Main & Standby pumps.
Proper indication of a functioning EMLUB as you call it would be the absence of any light - Black Panel - And yes according to the Manufacturers ECL "Land as soon as possible - Maximum flight time 30 minutes"
About your edited thought: Again not sure what you mean by "would the crew still have an accurate transmission temperature?" since the Oil temperature switch sits at the bottom of the MGB case, immersed in oil and measuring the oil temperature. Remember the S-92 Cougar crash report, the crew expected an increase in oil temperature associated with a loss of oil, which led the pilots to incorrectly rely on MGB oil temperature as a secondary indication of an impending MGB failure. So regardless of your oil temperature being below 128 degrees following a failure of the EMLUB system, the ECL states explicitly what to do.
Thanks for the info Peter.
When on course the instructor dealt with total loss of oil more than loss of both pumps. At least that was the impression I was left with. As I said I don't have my course notes to hand at the moment. Hence the question.
Of course in either case loss of pressure would lead to activation of the ELUBE system as per ECL.
As for my edited thought: My point (dull that it may be LOL) was that in the event of a total loss of oil there would be no accurate oil temp information but in the event of loss of both pumps there may be.
Just an aside nothing more. The S-92 accident was what brought it to mind.
When on course the instructor dealt with total loss of oil more than loss of both pumps. At least that was the impression I was left with. As I said I don't have my course notes to hand at the moment. Hence the question.
Of course in either case loss of pressure would lead to activation of the ELUBE system as per ECL.
As for my edited thought: My point (dull that it may be LOL) was that in the event of a total loss of oil there would be no accurate oil temp information but in the event of loss of both pumps there may be.
Just an aside nothing more. The S-92 accident was what brought it to mind.
A relatively quick and total loss of either engine or MGB oil will, of course, lead to a reduction in indicated temperature as the probe will effectively be measuring internal air temperature. I both cases when I have rapidly lost engine oil, in two different types of aircraft, the indicated temperature went down not up.
Last edited by industry insider; 5th Nov 2012 at 07:10.
My very basic thoughts on Oil Temp indications.
You would have accurate indication of the oil temp (still has oil in this failure mode)
However, the oil is not being pumped past the, now unlubricated, hot parts: so the oil temp is irrelevant, and could be falsely comforting. (Similarities with temp indications when the fluid is below the sensor. The classic case being car radiators: when dry, the indicated temp can drop...)
The elephant in the room, is the pieces of shaft/bevel gear potentially unrestrained in the TXMSN.
No light (on the MLube) is Normal
You would have accurate indication of the oil temp (still has oil in this failure mode)
However, the oil is not being pumped past the, now unlubricated, hot parts: so the oil temp is irrelevant, and could be falsely comforting. (Similarities with temp indications when the fluid is below the sensor. The classic case being car radiators: when dry, the indicated temp can drop...)
The elephant in the room, is the pieces of shaft/bevel gear potentially unrestrained in the TXMSN.
No light (on the MLube) is Normal
Last edited by That lights normal!; 4th Nov 2012 at 22:13. Reason: II posted while I 2 finger typed
"The elephant in the room, is the pieces of shaft/bevel gear potentially unrestrained in the TXMSN."
Having looked up into the bottom of an EC225 MGB with the bottom cover removed, I can assure you that when the shaft driving the bevel gear fractures at the weld and drops into the bottom of the sump, there is no way for shaft or gear pieces to be carried up into the other moving bits inside the gearbox. It is a fully enclosed chamber.
Having looked up into the bottom of an EC225 MGB with the bottom cover removed, I can assure you that when the shaft driving the bevel gear fractures at the weld and drops into the bottom of the sump, there is no way for shaft or gear pieces to be carried up into the other moving bits inside the gearbox. It is a fully enclosed chamber.
I don't think this will prove to be all that complex in the final analysis. I believe that they will in all likelyhood come back to what was reported here:-
Air Accidents Investigation: S3/2012 - EC225 LP Super Puma G-REDW
That was back in July 2012.
Air Accidents Investigation: S3/2012 - EC225 LP Super Puma G-REDW
That was back in July 2012.