North Sea Helicopter ditching 10th May 2012

[Woolf]

Special bulletin now released:

Air Accidents Investigation: S2/2012 EC225 LP Super Puma, G-REDW

Summary:
The crew of the helicopter carried out a controlled ditching following indications of a failure of the main gearbox (MGB) lubrication system and, subsequently, a warning indicating failure of the emergency lubrication system. All passengers and crew evacuated the helicopter into a life raft and were subsequently rescued. Two passengers sustained minor injuries. The investigation has identified a 360° circumferential crack in the bevel gear vertical shaft in the main gearbox, in the vicinity of a manufacturing weld, causing disengagement of the drive to both mechanical oil pumps.

Well done that crew!

[Vie sans frontieres]

That'll be what's meant by multiple indications! Good work getting it down from 3000'.

[212man]

The helicopter was in cruise at 3,000 ft with the autopilot engaged and at an approximate speed of 143 KIAS, 34 nm east of Aberdeen Airport, the crew were presented, almost simultaneously, with the following indications:

- WARN red light and aural gong
- MGB.P1 caption illuminating on the Central Warning Panel (CWP)
- CAUT amber light
- XMSN caption illuminating on the CWP
- M.P2 and S/B.P3 illuminated on the vehicle monitoring system (VMS)
- SHOT illuminated on the MGB control panel
- Zero indication on the main gearbox oil pressure gauge.

In addition, CHIP illuminated on the VMS and the MGB oil temperature started to increase.

The commander assumed control of the helicopter, reduced speed towards 80 KIAS, turned back towards the coast and initiated a descent. The crew activated the emergency lubrication system.

During the descent, the MGB EMLUB4 caption illuminated on the CWP, for which the associated procedure is to land immediately. The commander briefed the passengers and carried out a controlled ditching.

Out of interest, what does the 'SHOT' caption indicate?

Well done to the crew

[Fareastdriver]

BBC reporting that the oil pressure loss was caused by a crack internally on the rotor shaft. No idea of the 225's oil flow routing so cannot expand.

Out of interest, what does the 'SHOT' caption indicate?

It's French for 'FU@@ED'.

More onthe story here.

BBC News - Bond Super Puma ditching caused by gearbox crack

[soggyboxers]

WELL DONE

Would all the naysayers now like to join in wishing hearty congratulations to the crew of G-REDW for successfully completing a textbook ditching, resulting in the safe recovery of all passengers and crew and leading to the recovery of their aircraft so the AAIB can get accurate information as to the cause.

Thanks to HeliComparator for his early insightful and reasoned posts which were spot on.

A very well done to the crew and to their management for being supportive during the usual Sky News and BBC reports looking for someone to blame and coming out with all the "what-ifs" and other disaster scenarios

[AAKEE]

Well done !

Yepp, Very well done

[forwardassist]

So with the report stating that it was a crack in the gearbox that caused the MGB pumps to fail, are the other operators going to ground their aircraft to check for this problem or are they going to continue flying? I haven't seen anything with Bond written on it leave the airport today, so have they grounded all types?

[cyclic]

You can always check all three companies schedules online and see if they are flying. What it doesn't say is which type/variant they are flying with. I would hope that all the operators have read the initial report and are formulating a plan.

I'm sure HC will come up with some ideas as to why the SHOT indication was also showing.

[Woolf]

Sky is reporting that Bond have suspended flying on both the EC225 and also the L2. CHC and Bristows are apparently still flying as normal.

I have no insight knowledge but my gut feeling says it might be worth loosing one or two days of flying until an official EASA / Eurocopter announcement has been made just to be on the safe side. Not pleasant for people stuck offshore but it would certainly bring some peace of mind to passengers and crews alike.

[heliwanab]

would the AAIB not issue a warning to inspect,ground until further notice after the inspection showed cracks?
Or would that come from Eurocopter direct?

[cyclic]

It isn't "cracks", it is one 360 degree crack around a shaft. The AAIB has no authority to ground aircraft, it can only give advice to the authority.

[SASless]

At the risk of starting an old War all over again....does the 225 have a MGB design problem? I know all about the zillion hours X 10 to the ump power....and how the Laws of Probability work.....we have had that discussion too. But notwithstanding all that....is it Bond or the 225 that has the problem? Is the fix a simple Exorcism at the Bond Hangar or something bigger at play?

I am making no suggestions....just asking a question.

If it was a 92 involved....I know exactly where this discussion would be right about now.....and am just wondering why not with the 225?

I accept the 225 was seen as superior because of the Emergency Lube system but now we see that can also be done in by events. Added to the other problem identified with the MGB design....is the 225 as safe as once assumed?

[cyclic]

SAS

I think Eurocopter will need to come up with answers and quickly. Until that time there are going to be numerous theories and I would love to get into them now but because of how the press works over here, I am keeping my ideas offline. The exorcism does sound like the best one so far though!

[heliwanab]

cracks or crack the failing of the drive to both pumps suggests the separation of the shaft. perhaps not enough for any form of gap as such but is the component up to task or as SASless suggests, does the 225 have a problem?
The outcome is what matters for sure. Well done to the crew

[pohm1]

If it was a 92 involved....I know exactly where this discussion would be right about now.....and am just wondering why not with the 225?

I think the main reason for so much of the discussion and argument around the S92 was the lack of clarity as to what the aircraft was or wasn't capable of doing with no MGB lubrication, not the lack of a backup lubrication system. There is no doubt as to what to do in this case with 332/225 range.

P1

[The elephant]

Bond ditching

Excellent work, the answer for the loss of px in the Mg/b has been found. Let us hope this is the answer to the catastrophic failure as well, put some minds at rest. Interesting that Bond have suspended all 225 and L2 flights ( BBC report ). Great action by them, will this happen across the board I wonder? I guess a mandatory grounding will be imminent anyway.

[coatimundi]

We were told offshore some time ago that HUMS was a wonderful addition to helicopter safety. With this in mind, would someone care to comment on these words from the Interim Report:

These sensors had recorded increasing vibration
levels during the previous few flying hours prior to the
accident flight and were being monitored, in accordance
with the manufacturer’s maintenance manual.

It has raised questions out here on Safety Meeting Sunday - it would be good to give the troops some more feedback.

[Camper Van Basten]

Can someone explain how this internal crack led to an external oil leak, as reported in yesterday's media?

[TRC]

The investigation has identified a 360° circumferential crack in the bevel gear vertical shaft in the main gearbox, in the vicinity of a manufacturing weld, causing disengagement of the drive to both mechanical oil pumps

Driving both oil pumps from the same shaft - the main and stand-by - evidently enables a single failure to cause complete loss of oil pressure.

Am I being old fashioned by suggesting that any stand-by system should be totally seperate from the main system, and any failure (short of a catastrophic xmsn disintegration) that causes the main to fail shouldn't affect the stand-by?

[PlasticCabDriver]

"SHOT" is simply the wording on the Emergency Lube activation button on the overhead panel. It illuminates (I think, if someone has access to the FM and can correct me please do!) when 2 conditions are made: ac is in flight and the MGBP caption is activated, which was the case here.

Vibrations change on helicopters all the time. I don't know if similar systems are installed offshore, but I'm sure if one of them showed a similar change the immediate action would not be "quick, shut it all down, take it all apart and check it" but "interesting, we'll keep an eye on that". The procedures for doing so are well laid out in the aircraft maintenance documents, and in this case it was being done "in accordance with the manufacturer’s maintenance manual."

This is an interesting last line from the report:

"Detailed examination.......of the reason for the indication of a failure in the emergency lubrication system continues."

Not "failure of the emergency lubrication system" but "indication of failure in the emergency lubrication system"? Maybe I read too much into it but are the AAIB currently thinking that the Emblube system was in fact working, but the indications were that it was not, leading the crew to "land immediately".

Obviously no criticism of the crew here, the Emergency checklist is unequivocal in this case and ditching was the only and correct course of action, which they did perfectly.