New CHC S-92
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A few weeks back one S92A developed a crack in the main gesr box during final approach. This lead to all of the oil in the main gear box being drained. Even if the manufacuter claims dry-run capability, this is not a good thing.
Mars
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Shut the F... up
This is getting boring now
Can we not change the subject!!!!
Nick and HC who bloody care's about the S-92 and EC225
They are both entirley different machine's you can not compare them so why bother.
I think this slang match between the both of you has gone on long enough.
Can we not change the subject!!!!
Nick and HC who bloody care's about the S-92 and EC225
They are both entirley different machine's you can not compare them so why bother.
I think this slang match between the both of you has gone on long enough.
Nick
Yes a good TCDS. You fail to mention the equivalent safety findings nor the special conditions which some might consider to be fudges. Personally I would let you off with them though 'cos I'm a nice chap.
However it has to be pointed out that the crisp piece of paper does not do much for safety. JAR29.927 (c) says (and I guess FAR29.927 is the same)
And yet despite apparent compliance with this para, we know that the S92 cannot run for 30 mins following loss of gearbox oil. Quite how you got away with this cheat eludes me, but I can only assume that you fooled them into thinking it was "extremely remote". I guess that was because your fatigue evaluation didn't turn up the weak gearbox casing? Neither did your FMEA consider the consequences of the oil pump drive failure.
Since there have now been 2 in-flight incidents (that I know of, perhaps there are more?) where an S92 had a major loss of lubrication (in 1 case both pumps, in the other the oil), it can no longer be considered "extremely remote" so are you going to change the TCDS to show non-compliance? No, I didn't think so and that is why your tcds is not really worth the paper its written on. Its about as accurate and reliable as a Sikorsky performance graph. What other fudges are lurking in there that we have yet to find?
HC
Yes a good TCDS. You fail to mention the equivalent safety findings nor the special conditions which some might consider to be fudges. Personally I would let you off with them though 'cos I'm a nice chap.
However it has to be pointed out that the crisp piece of paper does not do much for safety. JAR29.927 (c) says (and I guess FAR29.927 is the same)
(c) Lubrication system failure. For lubrication systems required for proper operation of rotor drive systems, the following apply:
(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 flight crew of the lubrication system failure or loss of lubricant.
(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 flight crew of the lubrication system failure or loss of lubricant.
Since there have now been 2 in-flight incidents (that I know of, perhaps there are more?) where an S92 had a major loss of lubrication (in 1 case both pumps, in the other the oil), it can no longer be considered "extremely remote" so are you going to change the TCDS to show non-compliance? No, I didn't think so and that is why your tcds is not really worth the paper its written on. Its about as accurate and reliable as a Sikorsky performance graph. What other fudges are lurking in there that we have yet to find?
HC
Pumaboy,
As HC indicates, you do not have to read the thread.
I for one find the whole discussion extremly enlightening and, as I know both of the protagonists and their backgrounds, welcome the technical content of their discussion. (The recent post on autopilots was particularly interesting as was their discusion on EGPWS)
If you were to poll the readership, I would hazard a guess that the majority have learned a great deal from the writings of Nick and HC; like most others, I deplore the personal insults and find them somewhat superfluous (and not really amusing) but put up with them.
As Nick points out, unless customers and pilots take a stand on these enhancements, the necessary improvements in the safety record will not be seen.
If only we could have similar discussions on Human Factors.
Jim
As HC indicates, you do not have to read the thread.
I for one find the whole discussion extremly enlightening and, as I know both of the protagonists and their backgrounds, welcome the technical content of their discussion. (The recent post on autopilots was particularly interesting as was their discusion on EGPWS)
If you were to poll the readership, I would hazard a guess that the majority have learned a great deal from the writings of Nick and HC; like most others, I deplore the personal insults and find them somewhat superfluous (and not really amusing) but put up with them.
As Nick points out, unless customers and pilots take a stand on these enhancements, the necessary improvements in the safety record will not be seen.
If only we could have similar discussions on Human Factors.
Jim
Freedom Fries
JimL said
Perhaps NL and I should go flying together - Jim you can sit in the jump seat and film the goings on, then we can discuss it afterwards!
HC
If only we could have similar discussions on Human Factors
HC
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HC,
You squirm well. You think equivilent safety is worth discussing, while you do not answer the question of the deviations and regressions for all the safety rules. Nice touch. I call you back to the chart below where the 225 takes major exception to all the modern safety regulations. Cat got your tongue?
Here is one to discuss:
Regarding transmission lube, please be reminded that the S92 fully meets the FAR/JAR, in fact it ran the test to 3 hours, not the 30 minutes that the EC225 is reported to have run.
You squirm well. You think equivilent safety is worth discussing, while you do not answer the question of the deviations and regressions for all the safety rules. Nice touch. I call you back to the chart below where the 225 takes major exception to all the modern safety regulations. Cat got your tongue?
Here is one to discuss:
Regarding transmission lube, please be reminded that the S92 fully meets the FAR/JAR, in fact it ran the test to 3 hours, not the 30 minutes that the EC225 is reported to have run.
Nick
So if the S92 met the 30 min dry running time, how come the flight manual instructs the pilot to land/ditch immediately if the MGB oil system fails? Either Sikorsky is very stupid or in fact the S92 does not have the 30mins dry running time required by the FAR.
HC
So if the S92 met the 30 min dry running time, how come the flight manual instructs the pilot to land/ditch immediately if the MGB oil system fails? Either Sikorsky is very stupid or in fact the S92 does not have the 30mins dry running time required by the FAR.
HC
Is this alleged 3 hour run dry time at min pitch on the ground or at cruise speed?
Maybe Sikorsky would like to look at the Emergency Lubrication System bolted on to the Sea King after many years of MRGB oil being dumped over the side.
Maybe Sikorsky would like to look at the Emergency Lubrication System bolted on to the Sea King after many years of MRGB oil being dumped over the side.
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Just what part of "Inclusive" regarding full Part 29 compliance with the latest regs do you not understand, heliconfuser?
Still no answer about that missing 225 crashworthiness, huh, HC? Frog got your tongue?
How about the puncture resistance of the fuel cells on the 225 "Exemption, Part 29.963 Fuel Tanks, Puncture Resistance." Exactly how does the 225 fuel system in the belly fall short of modern fireproofing requirements?
Today's language lesson for Helicomparitor
English- Reversion: an act or the process of returning to an older condition
French- Réversion
English- Exemption: releasing or delivering from requirement to which others are subject, excusing. To make an excuse
French- Dérogation
English- Inclusive: comprehending stated limits or extremes
French- No direct translation, unknown word in French
Still no answer about that missing 225 crashworthiness, huh, HC? Frog got your tongue?
How about the puncture resistance of the fuel cells on the 225 "Exemption, Part 29.963 Fuel Tanks, Puncture Resistance." Exactly how does the 225 fuel system in the belly fall short of modern fireproofing requirements?
Today's language lesson for Helicomparitor
English- Reversion: an act or the process of returning to an older condition
French- Réversion
English- Exemption: releasing or delivering from requirement to which others are subject, excusing. To make an excuse
French- Dérogation
English- Inclusive: comprehending stated limits or extremes
French- No direct translation, unknown word in French
Just a small diversion.
Crab.
The S61 has had an emergency lube system for longer than I can remember,which in itself says nothing, but certainly the mid seventies. If the 61 needed it then, quite why the S92 was built without it is anyones guess!? New technology/materials in the MGB perhaps? Maybe Nick can answer that one.
P.S.
I bet "Wastelands" charged the MOD a fortune to embody and certify the system on your old buses!!
Crab.
The S61 has had an emergency lube system for longer than I can remember,which in itself says nothing, but certainly the mid seventies. If the 61 needed it then, quite why the S92 was built without it is anyones guess!? New technology/materials in the MGB perhaps? Maybe Nick can answer that one.
P.S.
I bet "Wastelands" charged the MOD a fortune to embody and certify the system on your old buses!!
Last edited by 3D CAM; 14th Nov 2007 at 14:37.
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SARCO,
I know nothing about the oil leak, I have emailed folks to find out. Stand by, please.
Regarding the aux lube systems in the 61, it is only for the high speed inputs, which are at 18,000 rpm, and are just bronze sleeve bearings. They fail utterly in about 30 seconds if not lubed, and usually result in dual cut shafts (autorotation) and possibly a fire. The ports for the sleeves were the last ports in the oil system, and therefore were starved if anything happened upstream of them (blockage or a jet failing to full flow.)
For the EC 225, the water/glycol aux lube was needed to certify the box because the transmission has so many old style lube lines snaking over its surface, each used to port the oil around the outside of the transmission to feed all the internal jets. This is 1960 design, most manufacturers dropped it 20 years ago. These external failure points, dozens of them, are judged by the JAR to be irredeemable as leak points, so the aux system had to be used.
The 92 has only two external lines, going to and from the cooler. These are protected by the indicator/isolation system and deemed by the JAR/FAR folks as fully compliant with the regulation as to oil system protection. All the other oil transmittal passages are part of the internal gearbox, immune from mechanic's feet and bad threads on line fittings and the like. The probability of needing the aux lube system was deemed an order of magnitude better than the older design that the 225 has.
Since these two lines might create a leak, the oil level is monitored by an oil level system, and any leak is indicated to the pilot, who then isolates the transmission from the cooler. The fly home is much more than 30 minutes, the test showed that the box allows flight at hot day for over 3 hours.
The rules for protecting a gearbox are the same for the intermediate and tail boxes, which on the 225 and the 92 are deemed compliant without any aux lube system. Remember, the consequences of such a failure are the same in every helo.
To advocate that another helo is not satisfactory for this logic while depending on it for your helo is a little duplicitous, frankly, or shows some ignorance about helicopter engineering.
I know nothing about the oil leak, I have emailed folks to find out. Stand by, please.
Regarding the aux lube systems in the 61, it is only for the high speed inputs, which are at 18,000 rpm, and are just bronze sleeve bearings. They fail utterly in about 30 seconds if not lubed, and usually result in dual cut shafts (autorotation) and possibly a fire. The ports for the sleeves were the last ports in the oil system, and therefore were starved if anything happened upstream of them (blockage or a jet failing to full flow.)
For the EC 225, the water/glycol aux lube was needed to certify the box because the transmission has so many old style lube lines snaking over its surface, each used to port the oil around the outside of the transmission to feed all the internal jets. This is 1960 design, most manufacturers dropped it 20 years ago. These external failure points, dozens of them, are judged by the JAR to be irredeemable as leak points, so the aux system had to be used.
The 92 has only two external lines, going to and from the cooler. These are protected by the indicator/isolation system and deemed by the JAR/FAR folks as fully compliant with the regulation as to oil system protection. All the other oil transmittal passages are part of the internal gearbox, immune from mechanic's feet and bad threads on line fittings and the like. The probability of needing the aux lube system was deemed an order of magnitude better than the older design that the 225 has.
Since these two lines might create a leak, the oil level is monitored by an oil level system, and any leak is indicated to the pilot, who then isolates the transmission from the cooler. The fly home is much more than 30 minutes, the test showed that the box allows flight at hot day for over 3 hours.
The rules for protecting a gearbox are the same for the intermediate and tail boxes, which on the 225 and the 92 are deemed compliant without any aux lube system. Remember, the consequences of such a failure are the same in every helo.
To advocate that another helo is not satisfactory for this logic while depending on it for your helo is a little duplicitous, frankly, or shows some ignorance about helicopter engineering.
Nick
At last you have finally admitted (in a roundabout sort of way) that the 92 has no dry running time. Its only taken 2 years!
Just to correct your justification, the 225 like the 332L/L2 before it, only has external pipework to the oil cooler. In the event of loss of oil, the oil cooler is automatically bypassed. If you look at the 225 transmission you will see a lot of pipes but those are for the glycol injection to give the 30 mins dry running time. There is no oil in them.
In the 92, similar external leaks require pilot intervention. Does the RFM still say "within 5 seconds"? If so, that is a very poor system for a multi-pilot helicopter.
Lets just check the safety score for a minute. You have the wonderous S92 which meets the letter of the FAR29 admirably. Then you have the EC225 which is a worthless piece of junk because it has the wrong writing on the TCDS. Well the 92 is the clear winner isn't it!
Or maybe we should get in touch with reality?
I know of all the events on the 225 fleet. I only know of some of the events on the S92 fleet - those that became public knowledge. In the first 10,000 hours of operation:
Engine failures: S92 - two. EC225 - none
Fires: S92 - one. EC225 - none
Bits falling off in flight: S92 - one (anti-vibe actuator). EC225 - none
Transmission lube critical failures: S92 - two. EC225 - none
Rotor system problems: S92 - one (tail rotor). EC225 - none.
That's all I can think of at the moment but I'm sure there are more. As I have said before, compliance with the letter of FAR29 does not make for a safe helicopter.
Whilst you might fare better in a crash in the S92, that is just as well because you will almost certainly need that protection. Given the choice between crashing in a crashworthy helicopter or not crashing in a non-crashworthy helicopter I choose the latter thanks.
HC
At last you have finally admitted (in a roundabout sort of way) that the 92 has no dry running time. Its only taken 2 years!
Just to correct your justification, the 225 like the 332L/L2 before it, only has external pipework to the oil cooler. In the event of loss of oil, the oil cooler is automatically bypassed. If you look at the 225 transmission you will see a lot of pipes but those are for the glycol injection to give the 30 mins dry running time. There is no oil in them.
In the 92, similar external leaks require pilot intervention. Does the RFM still say "within 5 seconds"? If so, that is a very poor system for a multi-pilot helicopter.
Lets just check the safety score for a minute. You have the wonderous S92 which meets the letter of the FAR29 admirably. Then you have the EC225 which is a worthless piece of junk because it has the wrong writing on the TCDS. Well the 92 is the clear winner isn't it!
Or maybe we should get in touch with reality?
I know of all the events on the 225 fleet. I only know of some of the events on the S92 fleet - those that became public knowledge. In the first 10,000 hours of operation:
Engine failures: S92 - two. EC225 - none
Fires: S92 - one. EC225 - none
Bits falling off in flight: S92 - one (anti-vibe actuator). EC225 - none
Transmission lube critical failures: S92 - two. EC225 - none
Rotor system problems: S92 - one (tail rotor). EC225 - none.
That's all I can think of at the moment but I'm sure there are more. As I have said before, compliance with the letter of FAR29 does not make for a safe helicopter.
Whilst you might fare better in a crash in the S92, that is just as well because you will almost certainly need that protection. Given the choice between crashing in a crashworthy helicopter or not crashing in a non-crashworthy helicopter I choose the latter thanks.
HC
Shell - thanks for that, it seems Nick's definition of 'run dry' isn't the same as the rest of the world's.
The Sea King ELS is a bit more sophisticated than the S61 system sounds - it has a seperate sump and utilises the torquemeter oil supply to lubricate all the crucial areas of the MRGB, especially the input shaft bearings. It may use external lines but allows several hours of fly home time providing the MGB oil temp remains below 145 deg C.
The Sea King ELS is a bit more sophisticated than the S61 system sounds - it has a seperate sump and utilises the torquemeter oil supply to lubricate all the crucial areas of the MRGB, especially the input shaft bearings. It may use external lines but allows several hours of fly home time providing the MGB oil temp remains below 145 deg C.
Shell, thanks for the correction.
Can somebody remind me what "extremely remote" in JAR-speak actually means. Am I right in thinking is one step less probable than the one that is "not in the lifetime of this helicopter type" - something like "not in the lifetime of this or any other helicopter type"?
In which case there is no way that the 92 should have got past 29.927. That means its currently not airworthy. What are the airworthiness authorities doing about that?
HC
Can somebody remind me what "extremely remote" in JAR-speak actually means. Am I right in thinking is one step less probable than the one that is "not in the lifetime of this helicopter type" - something like "not in the lifetime of this or any other helicopter type"?
In which case there is no way that the 92 should have got past 29.927. That means its currently not airworthy. What are the airworthiness authorities doing about that?
HC
OK I answered my own question. Here is the EASA definition of "extremely remote":
"means unlikely to occur when considering the total operational life of a number of aircraft of the type in which the equipment is installed, but nevertheless, has to be regarded as being possible. Where numerical values are used this may normally be interpreted as a probability in the range 10–7 to 10–9 per flight hour."
That's one event in 10 million to 1000 million flight hours. Nick, with actual failures running at one in 25,000 hrs do you still think your baby meets 29.927 or was it a con job? Maybe you could still persuade your FAA buddies that it does, after all its only a factor of a thousand out and what's that amongst friends!
HC
"means unlikely to occur when considering the total operational life of a number of aircraft of the type in which the equipment is installed, but nevertheless, has to be regarded as being possible. Where numerical values are used this may normally be interpreted as a probability in the range 10–7 to 10–9 per flight hour."
That's one event in 10 million to 1000 million flight hours. Nick, with actual failures running at one in 25,000 hrs do you still think your baby meets 29.927 or was it a con job? Maybe you could still persuade your FAA buddies that it does, after all its only a factor of a thousand out and what's that amongst friends!
HC