North Sea helicopter disaster: 'Very unusual for fleet to be ordered out of sky after mystery accident'
ANALYSIS
Published Date: 03 April 2009
By Kieran Daly
THE type of Super Puma that crashed on Wednesday is considered to have a very good safety record and is well thought of, both by the North Sea operating community and by the offshore workforce.
The problem is the regulators now have an accident where the initial indications tend to point to a mechanical failure: something seems to have happened very suddenly and shows signs of having ended in a catastrophic impact.
It is very unusual for the regulatory authorities to ground a fleet of aircraft because of an unexplained accident.
They normally take mandatory grounding action only when they have discovered a definite fault that may affect other aircraft. The reason for that is experience shows most accidents are one-off events, or at least have unique aspects to them.
That said, there are accidents where there is a generic fault with the aircraft. There was an accident off the Canadian coast earlier this month involving a Sikorsky S-92 helicopter. This is arguably the most modern civil helicopter flying today.
Even though it's the latest and greatest helicopter, one of these crashed, with a loss of 17 lives, as a result of a failure of a single metal fastener in the main gearbox. The entire fleet, including those in the North Sea, were grounded until the operators had incorporated the technical fix.
The difficulty for Bond and BP is their workforces become very concerned about flying in the aircraft. So, realistically, it's difficult for Bond to do anything except ground them, whether they think there is a safety issue or not.
The important thing to realise about helicopters generally is that they have unique vulnerabilities that don't exist in conventional, fixed-wing aircraft.
Because the engines and the rotors are separate from each other, you need a pretty complex mechanism to transfer power from the engines to the rotors.
That mechanism is vulnerable to failure, and if it fails then it almost certainly has very serious consequences. That is a major reason why they have a poorer safety record than fixed-wing aircraft.
However, over the past ten to 15 years the industry has made enormous advances by using Health and Usage Monitoring Systems.
This consists of a series of detectors placed all over the helicopter. They look for tiny changes in the vibration of the helicopter from one flight to the next, which may give an early indication of a serious problem before it can cause a disaster, and it brings huge safety benefits. However, this makes it doubly disturbing if you do have an accident that is caused by mechanical failure.
But it is important to mention that experience shows, in every accident, the initial indicators can be misleading, so we will have to wait and see what the cause was.
I think the CAA probably will not ground the aircraft, but you don't have to be an expert to realise that if you are Bond then it is difficult to avoid because of emotional and industrial-relations reasons as much as any safety reason.