Originally Posted by
tenfour
I am sickened to the stomach that in 2016 and 50 years since we started extracting oil in the NS, that we should still be having these all too frequent tragic losses of life.
I understand that there is an element of risk with any aircraft; after-all, there are so many things that could theoretically go bang. But my question is this: would the operators allow this frequency of failure or this level of calculated risk on a well-head or a production facility?
I am not sure how to match up the metrics of
catastrophic problems per flight hour per airframe (over millions of hours) to
catastrophic problems per "what unit?" per how many units per what unit of rig operation. You don't want to use dollars, and I agree with that not being a preferred metric for aviation safety. I am not sure that are comparing apples to apples.
there is an unacceptable frequency to any chopper incident in this industry, which I cannot help but feel that if such incidents were to directly impact production/revenue, they genuinely wouldn't happen ever again.
As you noted, this is why there is insurance. The cost spike from a total loss and loss of life is a non-trivial perturbation in the flow of cost over time. But that's just the dollar side. There's more to it than that, which is part of what you are getting at. I find your post well intentioned but ...
In a rotary winged aircraft, there are certain lethal "single points of failure" that are inherent in the beast. Because of their criticality, they have to be designed with a higher safety factor than a lot of other parts. (alby3z says it better in the post following this one). Major parts like the rotor mast, the swashplate, rotor blades and blade retention parts (that which holds the blade to the rotor hub) and many others. When one of these breaks under flight loads, other things break horribly. The laws of physics shall not be flaunted.
What is encouraging is that, over the years, designs more often accommodate something termed "graceful degradation." Example: if the gears start to eat each other, the systems have a way to detect those metal bits in the oil, a light goes on, and pilots have a clue that it's time to get out of the sky before it all comes apart. We've seen a few NS ditchings in the past ten years where the aircraft was lost but all souls recovered. The last 30 years of HUMS, and vibration analysis, has been a boon to catching problems early, before they become big problems. (That particular systemic improvement still has room to grow).
The core problem is that with certain dynamic components it is a binary issue:
on or off
alive or dead.
(Suggested reading topic: Mast Bumping, Bell, Huey (UH-1) 1960's or so. It was a feature of the rotor system design that was potentially lethal, but there were operational means to avoid that occurring and creating a critical failure. When you consider how many thousands of two bladed Hueys have flown, and are still flying, with the underslung semi-rigid rotor system, it is clear that lethal risks can be mitigated procedurally. The same is true for most mature helicopters: over time, the accumulated knowledge of "that'll kill you" has become known and each case has means and methods to prevent it.)
Another family of risk mitigation is in performing maintenance. A non-trivial percentage of that activity is
things to check before you fly every time you take the bird up. Exam question
: is the bird telling me that a key part is on the way to failure? Systems have been developed and rules crafted, and decision points laid out, to nip those in the bud and not fly the bird until any such condition is corrected. You have to go looking for them before each launch.
With the above considered: until the "why" of this accident comes to light, you can't know which of the safeguards already in place may have been missed and the holes in the Swiss began to line up.
Once the "why" is determined
the system as a whole can respond. It will respond one way if it's a novel, first time failure mode, or another way if it's a previously known failure mode.
(I'll take you back to the 1960's again, and a USN A-7 that crashed on a bombing run due to a wrench being left in during maintenance, flight controls binding, and no pull up. The system response to that is still in the USN, in the form of the formal tool control program I was raised with).
Until "why" is cleared up, the "this is unacceptable" line has nothing to build on if you are
looking at the whole system and all of its interrelated parts.
Accordingly, I refuse to accept that the downing of a chopper cannot be prevented.
Most of the time, it is prevented. You just don't see it because the result of "it is prevented" is folks going to and from oil platforms.
And while accidents do happen,
I'll be a bit nitpicky here and say that you contradicted yourself. You either accept that accidents do happen, or you refuse to accept an accident ... "the downing of a chopper"? Which is it?
Thanks for the post and its intention (from the heart).
If you believe, in your heart, that the only standard that you can accept is zero defects, I am not sure that such can be accomplished when looking
at the system as a whole. It's a good target to strive for.