more on helicopter crash.

[Adrian]

WE'RE GONNA NEED MORE CANS!

[The Natural Philosopher]

internally up to 200g is survivable

[Grimly Curmudgeon]

Because they sounded cool and were the next best thing to sex on wings.

[Grimly Curmudgeon]

Most common last phrase is, "Oh, f*ck."

[Grimly Curmudgeon]

You'll find the rest in Aladdin heaters around the area.

[Nightjar]

That, or similar, was what 'I wonder why it did that' replaced as the most common phrase overall as aircraft became more computerised.

Colin Bignell

[The Other Mike]

A circa 20G crash if an EC130 (an update to the Squirrel and about 500kg lighter than the 135) in the Netherlands was fatal. The seats and crashbox structure under them are suitable for about 14G.

Appears to be far less disruption to the airframe than that at Glasgow.

[GB]

I am no expert, but I would expect that what counts is both g's and duration of the acceleration. Which effectively means the relevant factor is the speed the passengers are travelling at once the progressively crushable part of the structure has been completely compressed.

That is because the severity of the tertiary collision inside the body depends on the speed at which the soft organs are moving when they hit the bony structure.

According to the crash report, the helicopter's vertical descent rate had slowed to 1700 feet/min immediately before the time of impact. That's just under 20 MPH. In a modern car, belted in, you'd certainly expect to walk away from such a low speed impact. Perhaps helicopter engineers need to look at a means of increasing the amount of absorption under the seats/in the undercarriage, so as to increase survivability?

[Martin Bonner]

Mechanically independent - of course. But both FADECs would have the same software (*). If the conditions managed to trigger a bug, both systems would fail in the same way.

*: NASA tried independent development of two lots of software for critical software. It turns out that quite often both teams misunderstand the requirements in the same way, and introduce the same bug. Given that "two teams" doubles the cost of development, you can get lower failure rates for the same cost by doing the development more carefully and testing more.

[tony sayer]

Weight perhaps?, also the direction of impact in a car more often than not from the front but in that sort of crash mostly vertical and direct up thru the spine.. Not nice;(,..

[Fredxxx]

I suspect the orientation of the body with respect to the axis of deceleration plays a critical part.

We are aware that a frontal collision in a car is survivable, and have seem extreme Formula 1 crashes where the occupants have walked away.

I'm aware that a rapid descent in a helicopter always seems fatal, though I am aware of 2 fitters, improperly seated died whereas the pilot survived because of the chair he was using was deigned to compress and meet the floor in a controlled manner.

[The Other Mike]

[GB]

You can see that the helicopter's legs just splayed outwards. If they were made stiffer, that would improve the survivability without the weight of the extra honeycomb structure they were testing.

[GB]

There's probably more room for the body's organs to move in a downward crash. So, maybe blood vessels like the aorta get stretched to breaking point?

[Tim+]

I would imagine that the weight of your head being jack-hammered down on to your spine wouldn't do either of those structures any good.

Tim

[Tim+]

Incidentally

Might explain loss of engine power but not the failure to autorotate.

Tim

[Adrian]

"Crack on the main rotor hub"

Didn't the AAIB interim report already say that was fine?

[Adrian]

Oops, sorry - that was a previous grounding...

[Dave Liquorice]

How do you draw that conclusion all it says is "During normal operations yesterday, one of our EC135 fleet has experienced an indication defect that requires further technical investigation."

Could be anything from an unexplained indicator lamp blowing to a Kegworth Disaster type fault. May not even be anything to do with the engines.

[Tim+]

Which is why I said "might". We're all still guessing but all the indications are of a loss of power followed by a failure to auto-rotate.

I doubt they would ground the fleet for one dodgy bulb so it's possible that a faulty sender or something interfered with the pilots control of the fuel pumps. Just a guess I know.

Tim