Football club owner dies in helicopter crash.

[brianw999]

The owner of Leicester City Football Club was killed along with 4 other people when his AW169 G-VSKP crashed shortly after take off. Initial reports identify a tail rotor problem as a probable cause.

https://www.bbc.co.uk/news/uk-england-leicestershire-46008703

[Evan]

The owner of Leicester City Football Club was killed along with 4 other people when his AW169 G-VSKP crashed shortly after take off. Initial reports identify a tail rotor problem as a probable cause.

This is a 6-year-old design with a lot of redundancies. It can't be loss of power. It's possible that the tail rotor drive failed. There was a report of a "grinding" noise and that the helo spun before the crash, which fits the scenario of tail rotor failure at low forward speed. Or maybe it hit something. There was no wire-strike protection on that one.

On the far side, this design has some advanced features that include a clutch mechanism to remove drive to the rotors with the engines running (thus eliminating the need for an APU) and a variable-speed main rotor system. After 6 years of operation, I would think any bugs would be worked out. But u... never... know...

[Evan]

Another interesting thing: Vichai Srivaddhanaprabha has been photographed leaving the stadium in a nearly identical AW109S (G-LCFC). That ship was registered in 2014, so the AW169 might have been quite new. I wonder if the pilot was unfamiliar in some way with the newer aircraft.
Also, the one photo of the wreckage I can find seems to show a nearly intact tail rotor. The boom is broken as one might expect in a hard landing but there are still three blades attached to the rotor hub. I think that rules out tail rotor strike.

The blades do not appear to be bent, suggesting that they were not turning upon impact.

EDIT: G-VSKP appears to have been registered with Leicester on 8/14/16. So after two years of operation, the pilot should have been very familiar with it.

[flashcrash]

Very sad news indeed. RIP to a man who transformed the club and saw them through to becoming Premier League Champions under Claudio Ranieri at astonishing odds of 500 to 1. Wembley Stadium is carrying Leicester City colors tonight. Heartfelt sympathies to the families and loved ones of all those killed in this tragic incident.

[xspeedy]

https://www.liveleak.com/view?t=91roh_1540837755

[Evan]

Certainly looks like tail rotor (drive?) failure and botched autorotation, meaning not perfectly executed under nearly impossible circumstances. The spin suggests the main rotor is still under power, while the rapid descent suggests the collective is down (instinctive reaction). Perhaps the FADEC got in the way here. Perhaps this is simply not a survivable scenerio by any realistic measure.

[brianw999]

Certainly looks like tail rotor (drive?) failure and botched autorotation, meaning not perfectly executed under nearly impossible circumstances. The spin suggests the main rotor is still under power, while the rapid descent suggests the collective is down (instinctive reaction). Perhaps the FADEC got in the way here. Perhaps this is simply not a survivable scenerio by any realistic measure.

For an autorotation descent to work effectively you need both altitude and time which the occupants here simply did not have.
If the tail rotor assembly broke in some way then the loss of control would have been almost immediate. Factor in the time to go through the “what the f**k, what’s happened, what’s it doing” and the time needed to disconnect rotor drive and set up autorotation and .....
..... RIP.

[xspeedy]

Much better video

https://www.liveleak.com/view?t=kfskw_1540930664

[Schwartz]

That really sucks. My understanding is that for tail rotor failure, the worst case is a hover without any forward speed... exactly what appears to have happened.

[Gabriel]

Stupid question but, if it was "just" a tail rotor failure, why did it fall? It's not like the tail rotor provides lift.

[brianw999]

The tail rotor stabilises the fuselage against the rotational torque forces of the main rotor. If something let’s go in the tail rotor drive then the tail rotor becomes a free turning windmill and ceases to stabilise the main rotor torque forces. The main rotor torque forces are then transferred to the fuselage which starts to spin leading to a total loss of lift and overall control. Autorotation is established if the main rotor is disconnected from the engine drive to turn it into a free turning glider but you need altitude, forward speed and time to do this. None of those commodities were available to the pilots and you can see the violently spinning fuselage as the aircraft came down.

[elaw]

Stupid question but, if it was "just" a tail rotor failure, why did it fall? It's not like the tail rotor provides lift.

As I'm sure you know, the tail rotor opposes the torque that's produced by the engine. I'd think if the tail rotor fails, the only way to stop the machine from spinning would be to cut engine power, which of course will cause the main rotor to stop providing lift.

I'd think in such a scenario it might be possible to autorotate, but maybe the 'copter got spinning so fast that the pilot got disoriented or was otherwise unable to perform the maneuver.

[Evan]

Stupid question but, if it was "just" a tail rotor failure, why did it fall? It's not like the tail rotor provides lift.

Out-of-ground-effect hover is the most dangerous maneuver even in a twin because you are entirely dependent on the tail rotor to counteract engine torque. In this sense, there is no redundancy. You must rapidly remove power from the main rotor and reduce blade pitch to prevent spin and thus you are removing the only means of significant lift. So you are going to come down at a high vertical rate with no directional control whatsoever.

This is why pilots at airfields tend to use a running takeoff to achieve some forward airspeed in/near ground effect before climbing. Of course, you can't do that in a stadium.

This is also why tail rotor drives are designed to be very robust. Tail rotor failures that are not the result of impact damage--or sabotage--are very rare.

The technique I learned for autorotation in this situation involves 'dumping' the collective, immediately removing power and pushing forward on the cyclic to build enough forward speed (60kts I think) in the descent to allow the fin to take effect and collective (blade pitch) to be added without inducing spin. Once you've achieved that you can arrest the vertical rate and flare the landing. But this isn't going to work once you have lost directional control. It's possible that there was no reasonable chance for autorotation here. I'd like to hear from a real helo pilot about that.

Watching the latest video, it appears that the tail rotor problem occurs just after cyclic input, as the pilot was transitioning out of the hover.

[Gabriel]

Folks, I understand what the tail rotor function is and what happens if you lose it (just want to add that, of course this doesn't apply in this accident, but if you have enough forward airspeed and are in a helicopter with fin, like most, you can keep flying forward without autorotation, there will be a sideslip angle that will be greater the greater the power/torque (collective input) and smaller the greatest the airspeed, there are combinations of torque and speed that give the max sideslip after which the fin would stall and the helicopter will start to rotate).

Years ago I've watched a training video in youtube, that now I cannot find and of which I can not tell the veracity, that showed how in a high altitude tail rotor failure at low or no speed, the helicopter would of course start to rotate out of control, but it can keep doing that without falling since the main rotors are still providing lift (no auorotation), then there was some technique with the collective to tilt the helicopter in one direction (thing tilting the main rotor shaft in one fixed direction while the helicopter keeps turning out of control around this now tilted axis) and the helicopter starts to drift in that direction, still spinning, until it builds enough speed for the rotation to start to slow down and then stop, then regular forward flight with no tail rotor can be resumed. Eventually you would fly the helicopter to a place where you can perform a safe autorotation (like an airport) starting with enough altitude and forward speed. They even recommended a high speed flare and skidding touchdown to have lateral control via roll until the touchdown. The sideslip angle will remain zero once you remove the torque and autorotate. The video went on to explain that, at low altitude and low/zero speed, they showed that the best move was not to autorotate and descend with power with the helicpoter spinning out of control, managing the descent with the collective (even flaring before touchdown) and letting the helicopter spin. Chances are that you will still crash and the helicopter may tilt over during the touchdown, but hopefully this would provide a low speed and low vertical speed.

While the video used PC simulators to demonstrate the techniques, they included some videos of real accidents where helicopters spinning out of control were able to perform a "safe" crash landing with power and spinning.

So my question is, again, why would a helicopter fall after losing the tail rotor? I understand the uncontrolled rotation, but not the vertical fall UNLESS it is induced by the pilot starting an autorotation but then of course the pilot would not keep (intentionally) the high vertical speed autorotation until the ground, he would NEED to pull up on the collective to try to slow down the vertical speed and make a ground contact at a survivable vertical speed.

I will go on here and speculate that there was more than just a tail rotor fail here. The way that the helicopter starts falling immediately as it starts spinning makes me suspect that there was a problem with the MAIN rotor too. Evan's mention that the incident seems to happen as the pilot start to transition to forward flight makes me think that perhaps the main rotor made contact with the tail rotor.

[brianw999]

The helicopter starts falling almost immediately because there was no forward speed to generate an “Autogyro” effect by keeping the main rotor spinning and therefore providing some semblance of lift. The point in helicopter flight that is the most dangerous is the transition from hover to forward flight. Basically, if something major goes wrong at that point when you have no altitude, forward speed and coordinated power then you are unlikely to recover. This is why pilots depart in reverse. They are keeping a possible option open of a return to the take off point if it all goes pear shaped.