Sid and Nigelh
 

B47 refers to this present thread on pprune that is running !
Nigelh - You only 'hear' what happened.
Why do people go on thinking they might know what the cause of this accident is when all of you base your reasonings on hearsay ?

Can I just point out that it was MD600 Driver in post 17 that first speculated a cause to this incident. All posts prior to that were identifying the type.

It was then general discussion for another 30 posts before KJ speculated about an engine problem; then another 26 before other speculations/observations are made by nigelh and md600 driver, both of whom I am led to believe are friends of Nigel F.

Thank you.


(this is post 122)

Are all these posts, honestly, the culmination of the many years of supposed experience that calls this forum home?
For those that have lost a friend, we all understand the sense of loss and disbelief.
Discussion and speculation is a constructive and natural way for everyone else to try understand what happened and, perhaps, learn something.
It is not a criticism on anyone involved, and should not been seen as such through the eyes of grief.

Absolutely agree. But if you are at high speed a quick stop is necessary for an immediate landing?

Not really - yes you have to slow down to land but a quickstop is executed at a safe height and usually involves coming to the hover before moving forward and down.

What is taught as a gate approach would be the usual method of going from cruise flight straight to a landing.

it all depends on what he was doing at the time - a previous poster said he was doing quickstops.

Before i get dragged into this even more , i would like to point out that nobody has said he was performing Quick Stops...plural . Also i cannot see any relevance of a quick stop with regard to a possible failure . Done correctly , as i am sure it will have been , it is not high stress and is a daily event for most people and if you think it IS high stress for the machine ...your doing it wrong .

This is what you wrote in post #83 Nigel - you don't say quickstop(S) but that is super pedantic as a defence.

I don't know how close to MAUM an Alouette with 5 pob is but coming to a high hover in light winds will require a lot of power - hence the comment about stress = even if the manoeuvre is flown very gently.

Crab, I once was taught the quick stop in a way so it smoothly ends at a safe hover altitude, not in a high hover. I think your definition is quite interesting but what do I know. This discussion is leading nowhere anyways.

In a single engine helo like the Alouette, the bottom end of your avoid curve probably isn't much higher than 10' - most quickstops are taught at 20 - 50' for tail clearance.

Depends on your definition of a safe hover altitude.

They should always be flown smoothly but you said it was an emergency procedure.

Crab .... Maybe your mil training is very different , but most of us civvy pilots can do a quick stop and come to a relatively low hover , certainly in ground effect . Therefore I really think you are talking nonsense somehow implying that it is " stressful " on the aircraft or even necessarily using a very high power demand ....as I said earlier ...if your quick stops are high stress and high power input ... You are doing them wrong .
Lastly , I think even you realise that the comment " doing quick stops " is , in this instance , hugely different to the comment " doing A quick stop " . You are trying to imply ,( as you so often do in your own inimitable self righteous way !!) a cowboy way of flying , which you really have no right to do . You are SO transparent ....!!!

For those of us non-rotary wing rated... can you explain what this `quick stop' is?
I assume a flare at speed which causes the helicopter to rapidly decelerate and then drop the nose down into a hover?

Tar

Yup that explains it nicely. What you have been hearing about high power demands and stressing the airframe can happen if the quickstop is done wrong or extremely aggressively ! However if done correctly puts no more power through the transmission system than a vertical landing

Nigel - you are trying to read far too much into my post that simply isn't there - you mentioned the quickstop in the first place and then stressed that you meant quickstop in the singular not the plural - you clearly feel the difference between one quickstop and multiple ones equates to cowboy flying - your words not mine and I have never suggested that anything untoward was going on.

Mil training standard height for a quickstop is 50', particularly for bigger aircraft where tail strike is a real danger - this is for academic training though and operationally could be much lower.

I am not so bullish about my own piloting skills to attest that I have never made a mess of a quickstop and I have seen some very interesting variations by students in my long time as an instructor.

Are you saying you have never got one wrong?

Yes, a quickstop should be flown smoothly and without drama but, at high AUM (if you are not used to it) and very light winds, the loss of ETL , especially following an aggressive flare, and the sudden increase in power required, can require rapid application of lever and pedal to prevent sink and hold heading - hence the comments about stress on the airframe.

Tartare - in case you are wondering, ETL is Effective Translational Lift - a helicopter phenomenon where a change in induced flow through the rotor gives a decrease in power required as you accelerate through about 12 kts TAS - the reverse is true on decel.

For Tar, an example of how to do it vs how not to do it (these have done the rounds before)

my that was an expensive quick stop !

Fuel interuption
 

With 4 pax what fuel load at takeoff was possible within mtow?
What fuel remained at the approach to the field ?
The Al2 flight manual proposes a cautious, flat, approach profile to the hover when remaining fuel is low. (Low fuel warning light at 60 litres)

An Al2 with square tank has the fuel pump /pick-up at the front of tank, during a noise high manoeuvre the possible loss of stable fuel feed/pressure (potentially at a point of high fuel demand) could contribute to a pilots challenge.

Did the tank remain intact ? What fuel remained ?
Could an untimely (brief) power fluctuation, if one occurred, have contributed ?

Thanks Fellas - impressive to see a machine of such size do that.

The accident report

The report was published early this morning. My own personal summary is that there was no technical failure; it was at high AUM and near forward CG. The rate of quickstop in these conditions (also noting a low noise down attitude in the hover - a result of fwd CG) would have needed lots and rapid aft cyclic which resulted in main disc contacting the boom.

Thoughts still with the family of the pilot and with the 4 surviving passengers.

It always amazes me that after 1 year of investigating the AAIB can't even get the important facts correct

The max gross weight is 1600 kg as the plate in the front of the helicopter shows ,more importantly because they make comment to their interpretation of the aircraft being over weight, using the correct figure the aircraft would have been nearer to gross weight and at 2kg over weight [their estimate } more that would that have been used on start up before flight

https://www.dropbox.com/s/rhu0o0zc89..._3613.JPG?dl=0


Fr0m AAIB report

https://www.dropbox.com/s/bfcoq7j9ul..._3612.PNG?dl=0

copy of plate in helicopter and from manual for 313B

https://www.dropbox.com/s/rhu0o0zc89..._3613.JPG?dl=0
https://www.dropbox.com/s/bfcoq7j9ul..._3612.PNG?dl=0

However, stunting and bunting at close to (or just over) MAUM with a C of G very close to the forward limit is foolhardy at best and certainly doesn't meet the concept of looking after the safety and well being of the pax.

45 degrees nose up is a ridiculous amount for a quickstop - especially at the limits of AUM and C of G.

Very sad that it proved fatal but there is only one person to blame.