Once again it’s a Super Puma that goes down. Why?
As I write this, bits and pieces of information about the Super Puma ditching just a couple of miles west of Sumburgh, Shetland, are trickling in. The news is not good.
Yes, another Eurocopter aircraft has suffered a major failure – the third in less than two years and, I think, the fourth Puma to have gone down since April 2009.
But this wasn’t a controlled ditching. It lost contact with air traffic control and disappeared off the radar screens at Sumburgh when on its final approach.
Moreover, by 10pm yesterday, it was clear that the Puma had broken up and three out of the 18 people on board were missing.
My understanding is that this latest incident involves an AS332L2 Super Puma MkII, the same class as the ill-fated Flight 85N that crashed 12 miles north-east of Peterhead on April 1, 2009, while returning to Aberdeen from the BP Miller field. All 16 aboard perished.
Outwardly, to the untrained eye, there’s no difference between an L2 and the EC225, two of which suffered catastrophic gearbox-related failures last year and resulted in all members of this class in North Sea service to be grounded.
But under the skin there are major design differences.
It happens that, not long ago, EC225s were given clearance to fly again, based on a number of modifications that the UK and European aviation safety bodies deemed acceptable pending redesign and manufacture of the gearbox driveshaft assembly.
My understanding is that none is yet in revenue-earning service.
The L2 that crashed in 2009 had significant gearbox issues. In November 2011, the Air Accidents Investigation Board published its Formal Report 20-2011 into the accident.
It was attributed to the catastrophic failure of the main rotor gearbox as a result of a fatigue fracture of a second-stage planetary gear in the so-called epicyclic module. Crudely, that means cogwheel failure.
There were various contributory factors but this is not the time to go into those. However, the various problems were dealt with and the L2 appears to have behaved itself, until now.
I’m presuming that, such are the sensitivities surrounding the Super Puma, the L2 will be grounded immediately.
If it isn’t, then I shall want to know the reason why, given that we are talking about almost certain catastrophic failure.
Yes, grounding for heavy-duty examination will cause massive disruption offshore, even more than is currently the case given the lack of EC225 aircraft.
But, by the look of it, this will be absolutely necessary.
For sure, the UK North Sea Helicopter Safety Group will be convening PDQ.
Doubtless the current CEO at Eurocopter will already have broken out in a cold sweat.
And you can bet your life that North Sea workers will be even more reluctant than they already are to step aboard a North Sea chopper.