You are right Jim the AD 2012-0115E that was in effect at the time would have excluded G-CHCN.

However what data or analysis was done to to allow the formation of that directive?

If there is a sound body of engineering work then that would be fair enough but if it exists then it isn't in the public domain. Even if it was discussed between the operators it seems extremely odd that 2 (of 3 or the majority) have decided to monitor more closely than the AD. Which suggests the formation of 2012-115E is flakey.

If the logic was flawed then how and what is or should be taken as correct for the future?

When I was flying the Super Puma in the 80's we didnt have the HUMS gizmo
We relied purely chip detectors.
If the gearbox was suspect it was probably replaced, this happened on a regular basis, on average...pulling a gearbox once a month!

Now this gizmo lets gearboxes go for a much longer time, this is a bit scary because I dont think it is that good at detecting a major fault.
Its not that intelligent, trend analysis or what?
OK for jet engines but not ok for helicopter gearboxes

There seems to me to be a major design flaw.
History will prove this fact.

I know this is not comforting info but I just want to view my feelings about this particular helicopter from my own experience of flying it.

I want to fly with confidence, I never felt confident with this particular helicopter.

Who remembers the first Super Puma to be written off at ABZ G-TIGD yes a flaw that was known in the Puma but forgotten in the Super Puma

Hums is a weak secondary back up, what is needed is a sound design that everyone feels safe with.

HUMS is a nice tool if you know how to use it.
I don't think all operators train their staff as well as they could do...

In a ideal world items would be strong enough to last but that probably means items will be more expensive and since the safety culture is also based on a risk to money ratio this will never happen:cool:.

RP

M O E

TIGD was of course a tail rotor drive fairing that came open and hit the tail rotor on short finals, there were some injuries but none fatal.

Sorry but you haven't got it right. Chip detection is still just as important as it was in the 80s. Chip detectors are useful for defects when debris is released - eg bearing surfaces degrading etc. But what it was no good at was detecting a crack where no debris was released.

That is the point of HUMS, it can in some cases detect a non-debris-releasing fault before catastrophy. There is certainly no suggestion of continuing to operate a gearbox that is generating debris on the chip detector, just because HUMS says it is OK.

The two techniques are complementary.

There were a lot of debris-releasing faults in the early days of the 332L back in the early 80s, but these were fixed by changes in operational procedure, design and materials, not by the addition of HUMS.

If you are not happy flying this type of helicopter, nobody is forcing you to do it and I suggest you get a different job, or one flying a helicopter that cannot possibly suffer any mechanical problem. Good luck with that!

In truth I'm afraid I read your post as an uninformed gripe against the Super Puma family, trying to "stir it" based on incorrect speculation. You are of course entitled to publicy air your opinion even if incorrect, but it would be better for the industry and the passengers if you desisted.

With respect HC I don't think that is fair.

Just look at the situation that exists around the EC225 right now.

You have EASA airworthiness directives (as recently as August 2012) relating to issues from the accident of G-REDU in Feb 2009.

You have what seems a total mess with the latest issues from REDW and CHCN where you find 3 operators, 2 aviation authorities, a manufacturer, an accident investigation branch and a helicopter safety working group unable to co-ordinate properly which leads to a situation where the CAA and EASA have differing airworthness for the same type.

I mean WTF!?!

Yes you are right HC
It has a history of design faults and they are still working on how to fix it

...as does every other helicopter that ever existed or will exist.

On the other hand I flew 330s and 332 L(1)s from 1971 until 2009 and I never had a moment of concern. I took part in the first trials in 1972 where we intensively flew aircraft so as to prove extensions to the gearbox's life from 800 hrs to 2,400.
The RAF bolted down the inclined shaft hinge pin in 1972. When I joined Bristow I suggested that they do the same thing to their 330Js. I wasn't listeded to because I was a crab but luckily one migrated about six inches out about a week later so they did it. Super Puma comes along, same system. Doogal (RIP) and myself protested. 'This isn't a Puma. this is a Super Puma'. The rest is history.
Neither of the two aircarft that ditched this year ditched because of the geabox mechanical fault. They ditched because the EMLUB warning system failed, otherwise they would have proceeded with their 30 mins clearance and made landfall.

made landfall???

really... and on what hard evidence are you going to back that statement? i would love to see where the evidence is that this shaft would have lasted 30 mins having already fractured!!!! :ugh:

The first one had a chip too remember ie multiple indications of something not very nice happening. Why wait for the noise/smoke/vibration?

re
 

In my small opinion...........those heli has a big insurance at the back......and when the FM say land immediately I will do immediatelyI don't care if is thrue or false and I don't care to wait for see what happen:ugh:

many thanks for your replies to my posts gents. It was not my intention to slate any one of the operators maintenance procedures or finger point. I have absolutely no doubt that they are all of an exceptional standard. After the tragic incident with the bond machine, we were given a tour around their facility and shown how they go about maintenance procedures etc. I was astounded at the attention to detail that goes into aircraft maintenance. It was very reassuring to see this. If only we carried out maintenance like that offshore!

I also take great comfort in the fact that the guys who fly these machines would not be doing so if they believed for one moment that they were unsafe. a point was made about gossip and rumours offshore regarding helicopters, that point couldn't be closer to the truth. the amount of rumours etc and some of the attitudes of members of offshore staff only enhances these rumours.

It would be usefull for us if the operators sent some information as to what was happening as it is found out. although I am sure there are probably legal implications in doing so.

Helicrazi.......Made landfall!!!

Absolutely no doubt that the emlube was working in both May and October ditchings and if it hadn't given the pilots a false warning of having failed, they would have been able to continue flight at 80 knots for 30 minutes. Land was within reach in both events, I believe.

How many times does it need to be repeated that the fractured shaft which drives both oil pumps has nothing at all to do with the emlube system which is situated outside the gearbox and has no shaft driving it, ever ? !!!

I have been flying EC225s for over 3000 hours and I'd appreciate that before anyone makes "knee-jerk" comments about this superb helicopter, they should first check their facts.

FED

Since I am not all that familiar with this aircraft, I ask for understanding:

Am I correct in understanding that the emergency lubrication didn't begin to provide lube (i.e. provide lube to the gearbox when the normal lube failed due to the shaft no longer driving the pumps)
or
that the emergency system (as described by Colibri above) was actually providing the back up lube, but the warning sytem told the pilots a different story.

No, you aren't getting any more lube, emergency or otherwise

hence no choice but to ditch?

My understanding is that "no lube was happening from the emergency lube" but I may be confusing myself or not reading your remarks properly.

i dont see how you can conclude that after that fracture the gearbox would withstand another 30 mins, regardless of your 80kts speed, EASA stated it may not be torque related, so flying at 80 kts and low torque seems irrelevant?

i do not doubt that emlube system was working, infract i believe it was working effectively, its the fracture that worries me about the whole integrity

The aircraft ditched due to a catastrophic failure of a major MGB component, the main shaft.

The indication that the EMLUB system failed was probably their saving grace. Who knows what the outcome would have been if they had continued flight for 30 minutes with the broken part of the shaft thrashing around.

Bravo73 :D

Colibri - take note :ugh:

No ! You take note. The bevel shaft which drives the two oil pumps is right at the bottom of the main gearbox and it is welded to the bottom of the main shaft.

When it fractured each time at the 360 degree weld, the shaft simply dropped into the sump, so that the bevel gear was no longer engaged with the two pumps.

No other components of the gearbox were, or could have been mechanically affected, except by lack of lubrication. Everything else in the gearbox just carried on working normally and all that was needed was glycol from the external emlube system to keep critical components cool.

This glycol was found in both affected gearboxes after stripping down and no damage was found on any other components. They are isolated from any possible contact with the fractured bevel gear shaft.

Ok, you direct me to any publication that states that no other damage was found and i may stand corrected?

otherwise, how do you know that the shaft wasnt tested in its true weight before it was sheared and after it has sheared it is not going to throw all the balances out? personally, i would be ditching as i dont think 'landfall' would ever arrive...

Your understanding is incorrect, the second comment is correct. The details are in the AAIB bulletin, I shall try and find it, Colibri49 is spot on as that is what I have read also.

That is the cause for the ditching, it is an entirely different discussion of whether if the Emlube didn't give a false indication whether the gearbox would have carried on regardless.
Si

It's in an EC bulletin (Safety information notice No. 2520-S-00)available to people who fly their products through the TIPI service and the text is:

So helicrazi are you standing in a corrected stance?

I'm off to bed, g'night.

Si

Yes I am big enough and ugly enough to admit I stand corrected, that report states the rest of the gear box was in excellent condition, however, that was after a few minutes, I'm waiting to see if 30 mins would have the same outcome...

I'll leave my good colleague Biggles (Oh! I see that he's replied already) to continue our battle to gain your understanding, but I'll also reiterate something which seems to escape the attention of many.

There are two separate faults to be sorted out by EC, but neither one directly affects the other until the unthinkable and unpredictable events of May and October (perhaps slightly more predictable after May).

The external emlube system works just fine, except that a pressure switch (or switches) is probably set at the wrong value and tells the pilots falsely that the emlube system has failed.

The cracks which allowed the bevel shafts to drop off the bottom of the main shafts in both ditching scenarios have never manifested themselves before in over 4 million flying hours using the same shaft design.

Something got changed relating to factors affecting the shaft in the last 18 months or so and when the shafts failed, this exposed the latent problem in the pressure switches of the external emlube.

Two separate problems ! Both must be sorted out to everyone's satisfaction before the EC225 resumes normal operations.

Ok for my understanding, hopefully a simple yes/no answer:

If both oil pumps failed for a different reason, let's say 'sods law' and the shaft is in perfect working order, I am assuming the emlube would have been actived and functioning correctly as before, in this scenario would we have had the 'fail' indication? Or is the fail indiaction purely a symptom of the shaft failure?

"If both oil pumps failed for a different reason, let's say 'sods law' and the shaft is in perfect working order, I am assuming the emlube would have been actived and functioning correctly as before, in this scenario would we have had the 'fail' indication? Or is the fail indiaction purely a symptom of the shaft failure?"

My dear Sir. I'm struggling to answer your two questions with one word.

But to your "in this scenario would we have had the 'fail' indication?" my answer is "Yes" because the pressure switches are still faulty.

To your "is the fail indiaction purely a symptom of the shaft failure?" my answer is "No" because the shaft driving the pumps is inside the gearbox and has no connection with the external emlube system.

Bogus twin statistics
 

these are factors which are not correctly taken into account in the bogus calculations which support the twin engined philosophy .... AND ditching is not dangerous enough to risk the dangers of dodgy gearboxes which can be fatal..

Helicrazy, the answer is no. As discussed the Emlube is a seperate system. There are 2 sensors on the emlube system. One for glycol pressure and one for p2.4 engine bleed air pressure. It was the p2.4 engine bleed air sensor that threw up the fail emlube caption. This system is in place for total loss of oil, not just loss of pressure due to pump failure. It is an add on and accounts for the mass of extra plumbing around the outside of the MGB. Hope this helps.

Helicrazi, the fail indication is simply that Emlube system has decided that it is not working correctly. It has nothing to do with the shaft, they are completely separate systems. In the event of indications of Total Loss of Oil Pressure, the Emlube is activated by the crew using a switch in the cockpit. If it works correctly, there will be no fail indication until the Glycol starts to run out about 30 minutes later. As far as the Emlube system is concerned, it does not matter what caused the loss of oil pressure, whether this is because ( as in these 2 cases) the shaft failed, or you may have a catastrophic oil leak, or 'Sods law' may have happened as you mentioned below.

However, your point about the balance of the MGB running without the big lump of metal welded to the bottom of the main shaft is, I think, important, and something EC needs to address in their testing.

I think this may be the first time any Authority (in this case EASA), has predicated the safety of a helicopter based only on HUMS indications. There is no other inspection, visual or otherwise, required.

Does this mean that HUMS has finally come of age?

I know the oil companies and CAA have disregarded the AD but EASA are happy to let the 225 fly if HUMS is closely monitored. This is a big step forward.

"However, your point about the balance of the MGB running without the big lump of metal welded to the bottom of the main shaft is, I think, important, and something EC needs to address in their testing."

If you look inside an actual gearbox at the relative size and mass of the main rotor shaft versus the bevel oil pump drive shaft, you will see that the analogy of "elephant vs mouse" would be apposite.

Furthermore, once the bevel shaft has dropped off the main shaft, there is no possibility of an imbalance arising, because the two shafts were centred on the same vertical axis before parting company.

It's about the same relationship in terms of vibrational consequences, as if a hub-cap dropped off your car wheel along the road. You wouldn't even notice it!

The shaft failures are just the final symptom. The root cause is more likely something else which changed in the last 18-24 months.

The nitrided steel shaft in question has 250,000 hours of flight time prior to May 2012 with no problems. EC is no longer looking at the shaft itself as being the root cause.

What is the 250k hours stat from? Its certainly not total hours from a fleet leader. In fact the gearbox that failed in October and May were very low hours.

In May the engineering analysis of G-REDW show that the broken components triggered the chip detectors in the sump I believe - which means bits of metal frag was in the oil.. That isn't good but for the fact the pumps aren't working so it goes nowhere unless of course you can suggest fragments travelled before the pumps fail totally (after all they got to the chip detectors).

Beyond that in the case of G-CHCN the HUMS data shows that the Red alarm threshold had been exceeded. So regardless of one pilot suggesting the vibration is insignificant it's significant enough to produce a red alarm.

The 30 min emergency lube is of course a safety net - but not in all circumstances. Given EC225 MGB issues since 2009 you would be almost crazy to continue flying for 30 mins knowing you had a MGB issue when you could have quickly ditched in flat sea alongside a ship. When bits of gearbox fire themselves out of the casing or you loose the main rotor parts being lubricated is irrelevant.

It is also wrong to say it's flown for millions of hours on the same design until 18 months ago. Were that the case you would find the fix to be simple.

This is a big mess - it's been poorly handled with very few on the same page. The worse situation is that there is conflicts between what best practice is and as we speak even EASA and the CAA can't agree how to deal with the EC225.

Seems EC have 'boxes on rigs and a helicopter about to start testing.

I think it is. They have to revert to the old welding system that has proved successful over millions of hours. This means that they have to wait until the welds have aged before being put into service; about three months, plus any certification.
All the bulletens are doing is trying to salvage some essential work out of the aircraft before that happens.

What is the 250k hours stat from? Its certainly not total hours from a fleet leader. In fact the gearbox that failed in October and May were very low hours.

Whoever stated that, presumably was taking a guess at the combined total hours of EC225 flying in the last approx 7years.

In May the engineering analysis of G-REDW show that the broken components triggered the chip detectors in the sump I believe - which means bits of metal frag was in the oil.. That isn't good but for the fact the pumps aren't working so it goes nowhere unless of course you can suggest fragments travelled before the pumps fail totally (after all they got to the chip detectors).

It might be possible that in the May ditching, the broken shaft could have fallen against the single chip detector in the sump and damaged it. As regards "bits of metal frag", when a weld breaks there arent any to speak of; perhaps minute particles which couldn't significantly damage other components.

Beyond that in the case of G-CHCN the HUMS data shows that the Red alarm threshold had been exceeded. So regardless of one pilot suggesting the vibration is insignificant it's significant enough to produce a red alarm.

The increased vibration thresholds to produce an amber or a red alarm are also minute, in order to give early warning of failure.

The 30 min emergency lube is of course a safety net - but not in all circumstances. Given EC225 MGB issues since 2009 you would be almost crazy to continue flying for 30 mins knowing you had a MGB issue when you could have quickly ditched in flat sea alongside a ship. When bits of gearbox fire themselves out of the casing or you loose the main rotor parts being lubricated is irrelevant.

Agreed completely. Calm sea and ship in sight which I've spoken to, or land half an hour away? It's a no-brainer.

It is also wrong to say it's flown for millions of hours on the same design until 18 months ago. Were that the case you would find the fix to be simple.

That's not exactly what was meant. There's no suggestion been made that the shaft design was changed 18 or more months ago.

The current lines of investigation by EC include any possible changes affecting the whole gearbox, which could affect the shaft adversely. One thought is that mods to the engine management system in the last 18 months or so, could have changed torque and vibration characteristics detrimentally for the pump drive bevel shaft.

Change of material spec, change of process it is all change of design to some degree - just depends how you use the word.

Any change untested is very silly and I think had I got my feet wet in G-REDW or G-CHC I'd be with my lawyer seeking damages as it's unforgivable to put onto service something untested.

As an aside since when did we start using total fleet hours as a benchmark for fitness for purpose?? 250k hours could just mean 1 million things lasting 15mins as much as 1 thing lasting 250k hours.. To exaggerate the point.

As an retired engineer I see 2 problems here, the main one being that the emerg lub system can't be tested on start up. The emerg lub system in the S61 took oil from a low point in the sump of the gear box, this low point was was part of a new sump that was part of the mod, I forget the amount of oil in it that could not be drawn on by the normal pump. The point is that it could be tested before flight. The 225 system can't as it uses glycol. To my mind the best fix (after fixing the shaft) would be to have a lub system that uses the same oil as the MGB so it can be tested.
The secondly the shaft hours might not be the same as the MGB. Some components, in the MGB, have longer ultimate hour than the MGB overhaul life. So the main shaft might be on it's second trip after O/H. I don't have a MM so I don't know the hours the shaft can do and though the MGB hours are said to be low nothing says the shaft is.

Pitts

Of course the fleet leader has not got 250k hours.....more like 10k hours! Its 250k fleet hours....

Pitts and Colibri

The 250k hours was quoted by EC in a customer briefing yesterday, their figures not mine. EC is not looking at the shaft or any changes between AS332L and EC225 from Carburised to Nitrided steel as being the primary cause of these failures.....there is something else happening, they think.

Sevarg, people like to hark back to the S61 as if it were wonderful (and in truth it was not bad, in fact very good for its age!). On that old lady, the Emerg lube system as you say was an electric pump using oil from a low point in the sump. It is therefore similar in concept to the standby pump on the Super Puma family, the only difference being the method of pump drive. Of course with hindsight having 2 completely separate types of drive (mechanical and electric) seems a good thing. However neither of these systems meets the need for continued flight following complete loss of oil, the S61 would not be compliant with the current rules in this respect.

This is where the 225 Emerg lube comes in. Since you have to consider the worst location of the leak, it really has to be a total loss system. In order to keep the total fluid required down to a reasonable amount, EC decided to use it sprayed with a lot of air, hence the need for less than 12 litres to last over 30 mins and I suspect ordinary oil wouldn't atomise or do the same cooling trick as the glycol.

Otherwise, I quite agree with you that the system's downfall is the inability to excercise the valves and pump, or test the switches, prior to flight. The only trouble is that the more stuff you add to allow test, eg a means of pressuring the system without putting glycol into the gbx, the more complexity you add and therefore reduce the reliability. On the other hand, we are starting from a place of pretty low reliability!

All that said, the ability to fly 40 miles still air is not the be all and end all, I would rather not have it but have a MGB that didn't suffer from bits breaking off!

Plus the S61 emergency lube only fed the high speed input shaft white metal bearings.

Jim

On the subject of 225 emlube, the problem seemed to be insuffient air pressure to activate the switch even with everything in-spec.

I just wonder if the group who designed the emlube system didn't talk to the MGB designers and so didn't realise that the crew would already have reduced to Vy and so didn't realise the engine would be running slowly hence low P2.4 air pressure.

An expeditious crew, faced with sudden double pump failure, would turn the IAS down to 80kts then the next action is to press the SHOT button to activate the emlube. 225 decel rate is 2kts/sec these days I think, so 150 to 80 is 35 secs plus a bit at each end, so after at the point where EMLUBE failure is being detected the engines are likely to be down around 20% total torque. I wonder if the EMLUBE failure is latched (once its on it stays on regardless) or momentary (would go out if pressure switches activate again.

Maybe the answer is to operate Training Idle switch #2 to get eng 1 working harder. I can just see that going into RFM section 3!