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If the case is that only the pilot is suddenly incapacitated, leading to an increasing yaw to the right, I suggest that an experienced fixed wing pilot in the other seat would know enough to stop the yaw.
If she knows the pilot has lost it, she would surely intervene with a bootful of rudder even if she did not know what else to do. |
Originally Posted by Gustosomerset
(Post 10298972)
So speculation as ever but given what has been observed so far it seems most likely that:
a) The aircraft was high enough at the apparent point of failure to avoid hitting the TR on any part of the stadium or other fixed object b) Therefore the failure was likely caused either by something else airborne hitting it - or some sort of separate mechanical failure Assuming the mechanical failure option, (in the absence of any clear evidence of another airborne object) one thing that still puzzles me is why the pilot chose to lift to such an apparently unnecessary height before attempting to transition into forward flight. Could it be that he was aware of some sort of anomaly on the lift out that made him want to gain extra altitude to have the option of an autorotation away from the confined space of the take-off site? If there was a problem near the ground he would presumably have just put it straight back down - so whatever it was presumably occurred somewhere between the height at which he would normally have transitioned (200ft?) and the height he eventually reached (1000ft?). To give this theory any validity, there would have to be some sort of anomaly warning (sound/vibration/warning system?) that would encourage the pilot to believe that continuing to gain height enough to attempt a safe autorotation was his best (or only) option. What might this have been? It would also seem at this point that something departs the aircraft, but i'm not talking about the white speck seen at around 45 secs of the video doing the rounds, but the other white flat object which appears to depart the scene travelling up and left at approx 53-55 secs. (part of tail rotor blade?) I will try to provide a link to a youtube video showing this. The media shyt regarding falling 'into a dead mans curve' (as if it is some mystical hell-like place that exists) is just laughable, and all of the so-called 'experts' that have been wheeled out and given their views, well, they've all either been seriously misquoted, or all talk absolute bollox to some extent. It's just as well that in the UK we have some of the best accident investigators in the world working on this. Some of the theories put forwards have been sensible and from the usual pro pilots on this forum, but the non-pilots who all suddenly become armchair experts do nothing but embarrass themselves when they put fingers to keyboards. I think those of us who fly helicopters every day for a living, and have at least had some experience of tail rotor failures in simulators etc, will have a pretty good idea of some of the possible causes of this tragic accident, but unfortunately what we don't have access to are the facts except as shown in grainy videos. So the media outlets will be trawling forums, and asking these crap-and-past-it experts for opinions based on poor real world knowledge, and a serious lack of facts. Again its a sad case of not letting the truth and fact get in the way of a good newspaper-selling story. |
Originally Posted by Arkroyal
(Post 10298680)
My thoughts keep reluctantly focussing on sabotage. Swift removal of TRGB drain plug? all billionaires cultivate serious enemies. really? doesn't this even embarrass you writing something as stupid? so someone quickly ran out into the centre of a brightly lit football stadium, with some step ladders, probably had to remove a panel, drained the oil onto the field, then just walked away? honestly some folk need to go get a life. you've been watching far too much crap on tv. |
Helimutt, thank you. It had to be said. I guess you got fed up with all the 1 in a million theories and daft perceptions out there. It seems incapacitation is the new buzz word on the street. I don’t know what the statistics are but I am pretty sure this doesn’t happen very often. Sabotage, haha. 300 hour aircraft-Very new type into service is exactly why the reason this is most likely a TR gearbox/drive fault. Remember it’s bigger older brother, the 139, and the early days of tail pylons falling off and blades letting go. There are dreamers and realists in this world. I guess it makes fun to have both types around. |
Does anyone on here know how close the anti-coll wiring loom sits to the TRDS?
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Yes, the gearboxes have "run dry" times. From memory the MGB is 53 minutes. I don't know about the IGB or TGB but they're under a lot less stress than the MGB.
As far as the "smoke/unburnt fuel" on engine start, it looks like steam to me. Had this quite a lot with 139 starts in cold weather with hot engines. Moisture would condense in the exhausts and give quite a good puff on engine start. Of course, the 169 doesn't have the monstrous exhausts of the 139! I also note that the wind is up the tail on start. Anyone know the critical wind quadrant/velocity for LTE???? Was the gear retracting on the climb? Unrelated but shouldn't it be after TDP when Vy is reached that the gear handle is moved? So hard to see details on the videos! |
What was TDP, anyone able to figure it out?
Anyone with CatA experience would know what I am talking about. |
Just something to bear in mind when criticising two of the better qualified TV speculators.. There is footage from at least two HD/UHD cameras that Sky for example may already have access to show them, even though it was BT Sport showing the match.. I do agree that it is initially insects on the CCTV but the other footage will confirm from there on. They may have also had CCTV submitted to them but not decided to publish it due to its nature (ie clearer and more shocking). The CCTV footage was only shown by the big stations due to the Sun doing so.. disgracefully. However it does allow us to rule things out so for us it isn't a bad thing.
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Originally Posted by Magplug
(Post 10298880)
It has been a few years since I flew heavy helicopters but fundamentally the loss of TR control 200-500 feet above the stadium was not survivable.
The AAIB will want to quickly establish the '4 corners' of the accident to confirm that all the components of the aircraft are present at the crash scene. One video shot seems to suggest that a component flew away from the aircraft with high energy immediately before control was lost, the only components posessing such energy would have been a MR pocket (or two) or a TR blade. The fact that the aircraft immediately lost yaw control indicates it may have been a TR blade.... Crash site pictures indicate 2 TR blades present but one is half missing, you could argue it had been consumed in the post crash fire but the edges appear jagged as if it had been torn apart rather than burnt. The AW 169 has an impeccable safety record with no history of TR blade mishaps or other TR drive or contol problems. So why in this case? TR blades are stressed in construction so as to survive a minor impact from a birdstrike and still perform their role. In this day and age modern helicopters do not crash because birds fly through the tail rotors. In-service failure due to substandard manufacturing is a possibility but frankly unlikely. It is much more likely that a foreign object struck the tailrotor causing sufficient damage to cause blade failure and separation.... But caused by what? The surrounding area several hundred yards in every direction will be thoroughly searched for debris.... who knows what else might be found? Might we be looking at the first fatal aviation accident due to an aircraft colliding with a drone? |
Originally Posted by tottigol
(Post 10299137)
What was TDP, anyone able to figure it out?
Anyone with CatA experience would know what I am talking about. |
Originally Posted by tottigol
(Post 10299137)
What was TDP, anyone able to figure it out?
Anyone with CatA experience would know what I am talking about. TDP is up to 400ft in the Variable TDP profile. Depends on the height of the obstacle. The calculation of TDP is: TDP=Height of Obstacle + Clearance Height from Obstacle + 80 ft. Using the graphs (poorly) and not knowing the ambient conditions/weights/exact height of obstacele etc, TDP could be around 330ft. That assumes the stadium to be around 200ft high. If TDP calculates out to be 400ft or more then you are weight restricted. Climb rate should be less than 300ft/min on the vertical climb. So from the video you should be able to (very roughly) estimate their height above the pitch when they looked to hit TDP and pole forward. All approximate and not to be taken as gospel!!! |
To add something to the debate-
I tried TRDS failure at 300' TDP in the AW169FFS. daytime, & knowing it was going to happen. I survived.....but only at the second attempt! Main problem was having to look inboard to get the engine mode switches , which are located significantly out of your line of sight if looking out of the windshield (using left hand, which means removing it from collective!). I honestly think the chance of getting away with it for real, single pilot at night are pretty close to zero. |
Originally Posted by noooby
(Post 10299131)
Yes, the gearboxes have "run dry" times. From memory the MGB is 53 minutes. I don't know about the IGB or TGB but they're under a lot less stress than the MGB.
As far as the "smoke/unburnt fuel" on engine start, it looks like steam to me. Had this quite a lot with 139 starts in cold weather with hot engines. Moisture would condense in the exhausts and give quite a good puff on engine start. Of course, the 169 doesn't have the monstrous exhausts of the 139! Anyone know the critical wind quadrant/velocity for LTE????! LTE - loss of tail rotor effectiveness. Jesus! ............. From the video......it looks very much like a sudden loss of TR thrust. That’s all that should be inferred. There are numerous possible reasons for that condition........none of which can be identified from the evidence in the video. |
Careful using any FFS for analyzing technique on this kind of emergency. They are not programmed for it and generally don't have the flight data anyway, so you are working off a programmer's hunch. Years ago the CAE 412 and Flightsafety 412 sims had noticeable differences to tailrotor malfunctions, corrected only after a Canadian Forces 412 that was fully wired for HUMS/FDM suffered a for real tail rotor failure and provided accurate modelling information. Looks like this accident will do the same for the 169 sim.
For all you sim jockeys, have a feel at the yaw difference between knocking the engines off and bottoming the collective. I used to do it old school with the aircraft on 212/412 and there was a substantial difference between the two that was not captured on the sim models. Same with the nose down overpitching. |
Originally Posted by helimutt
(Post 10297665)
watch the clip carefully ...at around 53-56 seconds.
https://cimg8.ibsrv.net/gimg/pprune....dba9f064ec.png |
If anything - this thread has brought out some complete and utter moronic statements from so called pilots.
Goes to show either the helicopter industry is plagued with idiots or infiltrators from another planet! Please think before you press "reply" FFS. Christ - why should aviation tremble................... |
Well, the BBC's "experts" are plumbing new depths for their analysis:
https://www.bbc.co.uk/news/uk-englan...shire-46044224 Do these people, or the BBC, realise how stupid they sound? "Mr Bray agreed: "It's normal because it's just starting up. When you start an engine up, sometimes you get some vapour or something coming out." ""He takes off, goes up and hovers above the stadium, because then he has got to assess which way the wind is coming and wind speed and everything else," said Mr Bray." Mr Bray said a mechanical fault was also possible, but he believes this is unlikely. "These things are checked to the nth degree and any professional pilot will want to make sure his aircraft is safe," he said. "Obviously, they are putting their own lives at risk. "It's very, very weird." ""Thankfully, they are not the kind of things that happen often and I certainly don't have any personal first-hand experience of a real one, and I don't know anybody who does." Mr Rowlands believes the pilot manoeuvred the aircraft to prevent loss of life to people on the ground. "The fact that no-one else apart from people in the aircraft were injured is pretty amazing and I think that's why it's testament to the pilot," he said. "It's quite a disorientating environment to be in and I think the pilot has done well because not only has he got control of the aircraft, but he's trying to minimise the impact of any incident." And, BBC, you might want to redefine what an expert is, because you appear to have found two who don't even approach the standards required to be labelled as such in an aviation context. The fact that I am in some small way paying for you to spew this crap makes me sick. |
Originally Posted by DIBO
(Post 10299273)
nothing sensible to add, except that the 'unidentified object' disappears during 3 frames in between it's appearance on the port side and then on starboard
https://cimg8.ibsrv.net/gimg/pprune....dba9f064ec.png |
The mention of 'dead man's curve' by the media is not so much rubbish as is being represented above.
It you suffer a TR failure in any conventional helicopter in a normal hover then you have no option but to check down on the collective and cushion the subsequent touchdown. If you are in a hover high above the ground then your chances of a tidy touchdown diminish with height. Away from the ground the only way to stop the spinning from the anti-torque reaction is to chop both engines by simultaneously retarding both power levers and dump the collective to enter autorotation. Unfortunately you now have another problem of sorting out the self-induced double engine failure. You now need forward airspeed of at least 40-60 knots to execute an engines-off landing. To gain that airspeed you have to pitch sharply nose-down which not only increases your rate of descent but appreciably kills some of your remaining rotor RPM which is your life blood in executing a successful EOL. The chances of a succcessful EOL from a free-air hover of between 50 and 1000 feet are negligible.... even before you consider the complication of the confined area beneath you..... that's the dead man's curve. |
TC......the good news is the Idiots among us usually thin their own Herd for us!:uhoh:
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Originally Posted by Magplug
(Post 10299344)
...Away from the ground the only way to stop the spinning from the anti-torque reaction is to chop both engines by simultaneously retarding both power levers and dump the collective to enter autorotation.
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@gullibell... Thank you for jumping in...... I was establishing the principle rather than trying to teach the technique!
@Jagwar... Good point about the Canada Geese. They are substantial birds and would one damage a TR? Who knows? They are however big birds that would probably show up on the video clip and they do tend to fly around in pretty formations, generally only flying by day. If there are significant bird remains on the ground, they will be found by the AAIB. |
So I’m just reading the various actions to take to maximise the probability of the theoretical best possible outcome, and I can’t help wondering why not use some or all left cyclic in addition to the forward cyclic to get the desired helpful airflow against the vertical stabiliser?
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Originally Posted by Magplug
(Post 10299344)
If you are in a hover high above the ground then your chances of a tidy touchdown diminish with height....The chances of a succcessful EOL from a free-air hover of between 50 and 1000 feet are negligible.... even before you consider the complication of the confined area beneath you..... that's the dead man's curve.
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Originally Posted by Gustosomerset
(Post 10299490)
So, if some of the observations above are correct and the pilot chose to climb to an unusually high hover, why might he have done so?
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OK, thanks. I understand. I guess I was just trying to see if any implication could be drawn from what some observers seemed to describe as an 'unusual' take-off. Evidently not.
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Originally Posted by Magplug
(Post 10299344)
The mention of 'dead man's curve' by the media is not so much rubbish as is being represented above.
<snip> The chances of a successful EOL from a free-air hover of between 50 and 1000 feet are negligible.... even before you consider the complication of the confined area beneath you..... that's the dead man's curve. I was only shown it because I asked to see it, but when I asked what its real-world applicability was, they said it would most likely be a skill for pilots doing line work and pylon work. They seemed to suggest that if you took out the pedal turn, you could achieve the same from significantly lower than that. |
Gusto, despite what some ‘experts’ are saying that take off was quite normal. Remember Ex is a has been and spurts is a little more than a drip! |
1 Attachment(s)
I have some experience of crash investigations, helicopter engineering and statistics.
Let me shed some light in response to previous comments on the TR: @ The pdf file below has a blown-up section of an image at the crash site (I can't yet post images directly). It clearly shows that: @The TR was complete and attached at impact. @ One blade was burnt by the fire after impact and appears to be broken in 2, with the outer portion lying on the boom just below the remaining portion.. @ One blade had damage to its tip. @ IMO the lack of damage to the blades suggests the TR was turning very slowly or not at all on impact. @ IMO the damage to the blade at the right bottom corner of the image almost certainly occured on impact with the ground. @ IMO the damage to the burnt blade is consistent with the rotor not turning on impact and the blade fracturing, possibly helped to fall off by the post-crash fire. On a final note, that a TR failure is a rare occurrence is essentially irrelevant to assessing whether it occured here or not. Even if it is a 100 million to one chance of occurring, it will occur to someone; we are not looking at the other 99,999,999 flights where it didn't occur. |
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Originally Posted by Magplug
(Post 10299411)
@gullibell... Thank you for jumping in...... I was establishing the principle rather than trying to teach the technique!
@Jagwar... Good point about the Canada Geese. They are substantial birds and would one damage a TR? Who knows? They are however big birds that would probably show up on the video clip and they do tend to fly around in pretty formations, generally only flying by day. If there are significant bird remains on the ground, they will be found by the AAIB. |
Originally Posted by asdf1234
(Post 10298970)
It's my understanding that the passenger pilot had a fixed wing licence and not a rotary wing licence .if that is the case, and please correct me if I'm wrong, how would her fixed wing experience help her in a rotary wing environment?
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Originally Posted by G0ULI
(Post 10298863)
I know that the weather at the time would appear to contradict the formation of a vortex ring, but could the explanation be as simple as that? High power vertical slightly reversed climb followed by a turn and drift into a vortex of descending air? For everyone's benefit, where can we find a comprehensive table of the weather factors, and precisely how they similarly cause - or 'contradict the formation of vortex ring', as you put it. I'm not convinced you know what vortex ring state is, given your phraseology. |
Don't panic!
Originally Posted by The Old Fat One
(Post 10298247)
Guys and girls that fly helicopters, or are learning to fly helicopters, will be able to discern the valuable posts from the obvious "b*****ks" or at least ask questions if they require clarification.
https://www.gov.uk/government/news/u...ccident-g-vskp The digital flight recorder is in our laboratory. Although subject to intense heat in the post-accident fire, initial work on it has allowed us to successfully download the recordings. Our inspectors are verifying the extracted information and have started the detailed analysis of its contents.We would like to thank everyone who responded to our witness appeal. Our investigators are examining the videos and photographs we have received. |
Originally Posted by Ewan Whosearmy
(Post 10299556)
When I did my PPL(H) in 1998, an AFI demoed an auto from the hover at 1,000'. Rolled off the throttle, dumped collective, pedal turned through 180, controlled RRPM with lever, nosed down for forward airspeed, flared and cushioned landing with lever in the normal way. Type was R-22.
I was only shown it because I asked to see it, but when I asked what its real-world applicability was, they said it would most likely be a skill for pilots doing line work and pylon work. They seemed to suggest that if you took out the pedal turn, you could achieve the same from significantly lower than that. As an aside, the R22 will also indulge maneuvers that an AW169 almost certainly wouldn‘t. Zero speed auto? Expect an extremely dangerous rate of descent once the aircraft has finished accelerating (this in itself would require hundreds of feet) - lethal at low altitudes; 180 pedal turn during such an auto would also likely cause huge structural stress. Can’t imagine test pilots having that high on their list of things to try. |
From the CV & FDR the experts can recreate the flight using the pilot’s inputs and the aircraft’s controls actual positions. They should reasonably quickly know if there was a failure of the TRDS, TRGB or TR controls. If there was a mechanical failure they should be able to check the HUMS data to see if it could have been spotted before it failed. If it could, they can check other AW169 aircraft HUMS data for similar trend(s) (this is much quicker and cheaper than grounding all similar aircraft). It is vitally important that all parties are open and honest in the interests of Flight Safety. I fear that some may be less inclined to be so. Time will tell. |
Originally Posted by b1obthebuilder
(Post 10299574)
She would know what yaw is. Also know what the peddles do. And be an extra pair of eyes for the pilot.
Flight controls: Considering the pilot's professional background, I would be surprised if the fixed wing pilot onboard didn't have the skill to fly that aircraft under normal circumstances. My interest would be whether a pilot with an experience and skills profile similar to her would be able to take on an aircraft at that height (that has already entered an unusual attitude) and recover from that successfully. |
Originally Posted by Sir Niall Dementia
(Post 10298745)
Unlikely that incapacitation could cause a reaction like that.SND
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Originally Posted by Mitchaa
(Post 10299557)
It certainly looks like a mechanical failure, 99% certainty based on the videos. Yet no emergency AD? No grounding? No response at all.
For issuing an AD you need to have an idea what exactly to look for. Also this requires the identification what gave first and how. See above. It could also simply be a maintenance issue (for the sake of the mechanics who last serviced it i surely do hope not) or indeed a Goose hitting the TR. Re the question if a Goose can damage a TR: You can bet so. Geese are veeery substantial animals (up to 15lbs !). When people are worried about a tiny DJI wiping out a TR, think about what an object 7 times as heavy will do. |
Originally Posted by flyems
(Post 10299612)
What would an aircraft response congruent with pilot incapacitation look like?
That surely depends on what the last action/reaction before passing out was: Could be stepping in one pedal. Could be pulling/pushing/doing something else with the cyclic. Could be pulling/pushing the collective. Could be anything. Could be nothing at all. |
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