Link is here

In my opinion, all that one can tell from that photo is that there has been a catastrophic, and very sad, helicopter crash. That's what the AAIB are for.
That 'device' is nothing more than a cover, or cap, for where the duplex bearing is housed.

nodrama, thanks for clarification...

How robust is this spider and duplex bearing?
separate component or integral with the TGB?
what's its overhaul life and inspection schedule?
greased bearing or oil supplied from TGB?
c'mon nodrama, if you're experienced, share and educate.

The nice thing, with a tail rotor failure in hoover or low speed is that you DIRECTLY and FIRST OF ALL goes for an autorotation by lowering the collective all the way to the lower stop. You don’t need to think if a cotter pin, a nut or all the tail rotor blades are missing. You -bang!- go for autorotation. If this accident was a tail rotor drive failure you had to land immediately, even if in trees, but here you had a few options like open areas where you probably could make a survivable ”landing".

Look at tailrotor failures like this: If you hesitate to go in autorotation you are toasted, but if you go in to a autorotation and it shows wrong, you can always change your mind. To survive a helicopter, always think negative for a positive outcome.

The different types of tail rotor failures and necessary actions taken are well known and are described in all helicopter manuals

Arizona, your answer is too simplistic and unfortunately doesn't take into account that not all tail rotor malfunctions involve a loss of drive/thrust.
In the situation where the tail rotor continues to be driven but pitch control is lost and the tail rotor goes to maximum positive pitch, entering auto-rotation might be the last control input you ever made.

Shy, I am reminded of an old aphorism (maybe from Einstein) that a great many complex problems have simple, clear, and wrong answers. (ref to what you responded to) :cool: I'm with you; an incorrect response to a particular malfunction can make things worser faster.

Blimey, this is still rumbling on.......

Crab, simply as a matter of interest and as I have easy access to a Level D 139 FFS, I had a go yesterday at using the technique discussed by you and DB. Even in the sim, and I knew it was coming, I very quickly became disorientated. I even found it difficult to take my hand off the collective to kill the engine mode switches. I felt I had no control whatsoever of the helicopter and was just along for the ride. No real thanks to me, the sim helicopter did remain level and I eventually put the collective down quickly. I got away with a successful level, spinning landing but I was very surprised at how quickly I lost all references. I carried out this exercise from 20 ft. From 400 feet I have absolutely no doubt it would be impossible. IMHO and as we seem to all agree, those poor guys didn't stand a chance.

Hi-Hover, take a look at the Cardiff Police TR Malfunction. In the report the Commander stated he got totally confused by the image outside the windscreen so he settled on looking out the side window. This seemed to provide enough references for him to lower the collective, power on, and accept a trade of between ROD and yaw rate. He states that as he saw the surface appearing he pulled the collective all the way up to cushion the impact. Power on throughout. However, I am not sure if the references in any SIM would facilitate this or indeed of the flight loop allows for a reasonable attempt. Different type (355) also.

Sure, I agree, simulation has limitations, it was a different type from your student, and not even a 169. My point is simply that, after 40 years and 14,000 hours in the game, and being ready for the exercise, and having been in a helicopter with a tail rotor failure, I found it quite impossible to accept the rate of yaw with any form of control. I would need much more spare capacity.

Meanwhile...back to pointless speculation. Nodrama states that 'The aircraft that is the subject of this thread had flown less than 400 hours.'. Apologies if this has been stated elsewhere and I've missed it but what maintenance inspections would it therefore have been subject to since being built in 2016? - and would any of these inspections specify detailed examination of the tail rotor parts that are the subject of the AD notices as discussed above?

HiHover - I didn't say it would work but compared to a zero speed auto to EOL from 400' it might be the lesser of two evils:ok:

Perhaps the entering auto but keeping the engines running and using them to cushion the touchdown - if you can judge it - might be a refinement of the idea.

Either way I am in no rush to try it out!

You could be right mate. I was just astounded at how little control I had in trying to keep her level and reduce the yaw rate.

The beauty of the Sim is you can try it over and over and crash repeatedly....and at some point call it a day and head for a Pint on wobbly legs!

the IAF lost a Bell 212 (or 412 maybe) after a Pilot had picked up way too heavy a load on the Hoist....and came to our Facility to see if they could replicate the event.

I played with the Lateral CG Parameters to arrive at their calculated data and after about a dozen or so attempts we actually got to where we could fly out of the situation by using some very un-unorthodox control techniques which were quite counter-intuitive.

A large police department aviation unit came to us and wanted to practice autorotations and tail rotor failures at various HOGE heights....and we found that to be very interesting as well.

Whether the actual aircraft would react exactly as the Sim (or conversely....) was not the point of the exercises but determining what actions improved the situation was.

One thing for sure....we could prove certain actions were very bad juju and immediately made certain situations absolutely uncontrollable.

Get back in your box of tricks and experiment.....just do not activate your "Crash Over-Ride" as even a Sim can hurt you if left to its own.

hihover
And they were put in that position by the regulations in the name of safety...

HiHover, what is your view of the Landing Gear being raised prior to the TDP?

How do we know that it was?

Hmm.... Be interesting to know what regulation you think would ensure a safe profile to get out of a football stadium with a tail rotor failure! Somehow ,I dont think you can avoid exposure to a low speed/high torque environment.

Hihover......if you have free access to a Sim....and care not to utilize its great potential for learning and exploration of how a helicopter reacts to unusual events....please understand I find that attitude discouraging.

You have a golden opportunity and seem to be throwing it away.

Take the Sim out of motion....and run the scenario that way....so you only have the Visual and Instruments operating while the Sim sets happily on the blocks.

212Man from AAIB Special Bulletin:

The helicopter then began a climb on a rearward flight path2 while maintaining a northerly heading. Gear retraction started as it passed through a height of approximately 320 ft. The climb then paused. Heading changes consistent with the direction of pedal movements were recorded initially, then the helicopter entered an increasing right yaw contrary to the pilot’s left pedal command. The helicopter reached a radio height3 of approximately 430 ft before descending with a high rotation rate.

SAS....:):):) I have a job. Please feel free to be discouraged by me maintaining my employment. :):) When I have time I will have another look.

Yes, I've read the report (in fact it was me that posted the link here first). But, where in that paragraph does it state what the TDP height was?

Earlier a poster, who would appear to be familiar with the type, posted this:

Chop, take-off profiles are designed to give us the best chance when dealing with an engine failure, and they actually work very well if you stick to the profile when you lose an engine. Sadly, it would be impossible to write a similar profile for the catastrophic tail rotor event because control is effectively lost. It is not lost when an engine fails.

DB. Not sure why the gear was retracted, I haven't flown the 169 and know very little about it. In truth I don't believe it would have made any difference. Clearly, if he had suffered an engine failure before TDP he would have had to be quite slick with the gear but from that height I'm sure he felt he had plenty time to put it down again if required. Personally, I raise the gear when it is of no further use to me (rather than 200 feet on climb out). I normally operate from a 10,000 ft taxiway so I have the option to reject for quite a while.

212Man, I am assuming that as forward flight transition was not attempted prior to the Gear being raised that his calculated TDP had not been reached or indeed missed as events transposed.

I think though, that the salient point is should retractable landing gear be raised prior to achieving a sensible amount of forward airspeed and height. Obviously prior to TDP the gear should of course remain available for a reject. In big helicopter world, as you know, we generally do this at Vy+200 feet. More to avoid distraction between VTOSS and Vy and often to conform to a critical performance profile.

However, if we accept that the landing gear is able to absorb some considerable energy in a high ROD touchdown, then maybe the Vy+200 feet (both conditions having to be met), is a good compromise should the RFM not specify for the operating conditions.

I guess what I am really alluding to is would the outcome in this instance have been improved if the gear remained down to absorb the initial energy at impact.

Yes, I agree with you that even if they had reached TDP, the logic behind early retraction is not clear, although another poster suggested it has a low gear limit airspeed (which I queried and can only assume is related to it being electrically actuated, not hydraulically). I also agree that the outcome of a heavy landing on the undercarriage is likely to have been different to what actually happened. However, when you look at the Kenya Police AW139 accident where they all survived from a similar rate of descent - also with the gear retracted in a hover - and the relatively low level of obvious structural deformation in the early photos taken before the fire really took hold, in this incident - I shudder to think what was going on inside on the ground.

You are obviously correct, however the profile used was designed to mitigate a one of two engines failing, but increases the exposure time on the absolute dependance of the one and only tail rotor. I can't help but think a diagonal forward acceleration from the far downwind corner and a zoom climb at the upwind corner would have resulted in less exposure time and less stress to the tail rotor. This obviously puts more reliance on the engines, but they are very reliable these days and there are two of them!

Chopjock, the profile you propose would require reject distance available if the helicopter is above the OEI-IGE Hover Mass. You would also need to prove you could clear the stadium OEI after TDP on the remaining engine. Its really difficult to make this work when the distance available are so short. That's why the Rearwards Profile (VTOL Helipad) was conceived. To overcome these issues.
Having said that, the fact that this, and other TR malfunctions have occurred leading to loss of the aircraft and sometimes occupants, at low speeds means you are making an argument. How does the likelihood of a TR event compare to an OEI before TDP?

Chopjock,

As always you think you know better than those who actually do the job. However, most of us tend to operate the aircraft in accordance with the manufacturer's certificated performance procedures, even those of us not operating for public transport (where it is usually mandatory). It is sometimes a condition of the aircraft insurer (and therefore a requirement / condition of maintaining one's employment status with the operator) and it is always a condition of a CAA congested area written permission.

Hi 212man, it is a long time since I flew retractable undercarriage aircraft but I always thought/assumed that the gear was retracted as soon as possible after TDP in order to minimise drag during the acceleration to Vtoss/Vy, I do wonder whether this was another hang over from fixed wing A/C where the target speeds are higher and so the drag had a bigger influence. Obviously those operating single pilot might feel there would be more important considerations during a busy stage of flight!

Cheers TeeS

Just like what I said earlier...

Chopjock, you are the ultimate laxative.

You continue to put forward your ridiculous views in the face of logic and weight of informed opinion against you. It would not surprise me if you were the twin (or alter ego) of the other fool on this board.

Jim

Now there is a thought......ONLY two Fools in this Forum!:D

Don't forget me!

Except no consideration at all about longer exposure time and total dependance on the tail rotor...

TeeS, no the certification and so hence RFM profiles assume that the gear is left down until Vy and 200 ft agl. for a conventional accelerating departure as it is assumed that the pilot/crew are too busy concentrating on achieving the first segment climb at Vtoss to be operating any other controls. For a procedure where the TDP is already above 200 ft I would assume that retraction would take place at Vy.

Chopjock - what stress are you talking about? This is a tail rotor on a Part 29/CS29 certified modern machine, not something on a balsa wood aeroplane with a wind up propeller. Do you seriously think that a gentle climbing imanoeuvre is somehow placing any components in jeopardy?

Hi Chopjock, so you have backed your helicopter into the corner, accelerated as fast as possible towards the opposite corner (135m away according to Google Earth and that might just allow you to get to 25-30kts before you hit the far stands) and then 'zoom climbed' at a moment when you guess that your angle of climb will just avoid the stadium roof. Thankfully your one engine (one of my two engines) hasn't stopped because the engines are rather reliable, the climb continues until you get to the top of the stadium roof whereupon you continue an acceleration/climb to a suitable height. If at any time an engine stops (except in the first few seconds of acceleration or on reaching a safe height), the tail rotor quits its job, the rotor head lets go or you just overestimate your guess at what climb angle you were going to achieve, you stand a good chance of killing your passengers. How on earth can you argue that you have reduced any exposure times!!
Cheers
TeeS

Chopjock, don't think that the exposure to TR failure poor outcomes is restricted to zero speed hovering. TR Malfunction risks are present throughout the envelope and decrease significantly with speeds above Vy, However, in a twin, TR drive failure anywhere in the envelope turns you effectively into a SEH as an autorotation is generally required. Unless you have a Fenestron behind you whereby your options are significantly increased.

To illustrate my rather awkward point. If we all agreed to depart in accordance with your suggestion (Lets call it the "Corner" profile), losing the TR control or drive anytime in the first 70 knots would see you in a smoking heap. Up to 100 kts in the climb out your arse would be eating the seat cushion and the prospects of survival still 50/50. There are no easy alternatives.

That's why others on this thread (and you have managed to stimulate JimL into a frenzy), think you somewhat lacking in the old common sense department. However, try not to get defensive and think carefully about what I have written. This is nothing new. TR Malfunctions and Drive Failures present limited prospects of success wherever they occur.

TeeS
How long does it take to VTOSS using CatA profile V a "Corner" profile?