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Helicopter down outside Leicester City Football Club

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Helicopter down outside Leicester City Football Club

Old 27th Nov 2018, 20:07
  #841 (permalink)  
 
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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?
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Old 27th Nov 2018, 20:44
  #842 (permalink)  
 
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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

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!
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Old 28th Nov 2018, 01:05
  #843 (permalink)  
 
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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.
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Old 28th Nov 2018, 02:29
  #844 (permalink)  
 
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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.

Last edited by SASless; 28th Nov 2018 at 02:41.
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Old 28th Nov 2018, 09:01
  #845 (permalink)  
 
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No thanks SAS, I’ve seen enough. Unfortunately, when faced with an issue that requires immediate action, we revert to basic mode and we generally deliver whatever our survival instincts think we should. I can’t think of a worse position to suffer a catastrophic tail rotor issue.
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Old 28th Nov 2018, 09:09
  #846 (permalink)  
 
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hihover
I can’t think of a worse position to suffer a catastrophic tail rotor issue.
And they were put in that position by the regulations in the name of safety...
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Old 28th Nov 2018, 09:11
  #847 (permalink)  
 
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Originally Posted by hihover View Post
No thanks SAS, Iíve seen enough. Unfortunately, when faced with an issue that requires immediate action, we revert to basic mode and we generally deliver whatever our survival instincts think we should. I canít think of a worse position to suffer a catastrophic tail rotor issue.
HiHover, what is your view of the Landing Gear being raised prior to the TDP?
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Old 28th Nov 2018, 10:12
  #848 (permalink)  
 
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Originally Posted by DOUBLE BOGEY View Post
HiHover, what is your view of the Landing Gear being raised prior to the TDP?
How do we know that it was?
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Old 28th Nov 2018, 10:20
  #849 (permalink)  
 
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Originally Posted by chopjock View Post
hihover

And they were put in that position by the regulations in the name of safety...
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.
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Old 28th Nov 2018, 10:58
  #850 (permalink)  
 
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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.
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Old 28th Nov 2018, 11:24
  #851 (permalink)  
 
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Originally Posted by 212man View Post
How do we know that it was?
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 pilotís left pedal command. The helicopter reached a radio height3 of approximately 430 ft before descending with a high rotation rate.
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Old 28th Nov 2018, 11:39
  #852 (permalink)  
 
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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.
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Old 28th Nov 2018, 11:53
  #853 (permalink)  
 
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Originally Posted by DOUBLE BOGEY View Post
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.
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:

The TDP is 115ft + the height of the obstacle in your takeoff path so I’d guess a minimum of 250-300ft.

Last edited by 212man; 28th Nov 2018 at 12:05.
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Old 28th Nov 2018, 12:05
  #854 (permalink)  
 
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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.
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Old 28th Nov 2018, 12:11
  #855 (permalink)  
 
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Originally Posted by 212man View Post
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?
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.
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Old 28th Nov 2018, 12:28
  #856 (permalink)  
 
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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.
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Old 28th Nov 2018, 12:36
  #857 (permalink)  
 
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Originally Posted by Non-PC Plod View Post
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.
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!
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Old 28th Nov 2018, 12:52
  #858 (permalink)  
 
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Originally Posted by chopjock View Post
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?
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Old 28th Nov 2018, 12:56
  #859 (permalink)  

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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.
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Old 28th Nov 2018, 13:04
  #860 (permalink)  
 
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Originally Posted by 212man View Post
Yes, I agree with you that even if they had reached TDP, the logic behind early retraction is not clear
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
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