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Helicopter down outside Leicester City Football Club

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Helicopter down outside Leicester City Football Club

Old 29th Nov 2018, 06:20
  #861 (permalink)  
 
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I think TC knows that - it was a throwaway remark based on some of the ideas Chopjock has come out with.

He could at least have googled Cat A/PC1 profiles to understand them before posting......
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Old 29th Nov 2018, 06:30
  #862 (permalink)  
 
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Originally Posted by Hughes500
TC

He is actually a helicopter pilot, having done his PC's for the past 7 years or so ( he is actually a very good handling pilot, including a successful landing with a stuffed tail rotor in an Enstrom and an engine failure in a Hu 369) He is a single engine pilot so is asking why one has to climb quite so high when in a single you wouldn't. I suppose I can understand what he is saying, but he may have a hypothetical point are the manufacturers concentrating too much on engine failures rather than the plethora of other problems.
If he has survived a TR and an Engine failure he deserves some respect. Certainly experienced more have I have in the last 35 years.
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Old 29th Nov 2018, 07:31
  #863 (permalink)  
 
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Chopjock,

To reiterate what Double Bogey is saying - you seem to be hung up on the idea that getting VTOSS will somehow protect you from TR failure, and that being under this speed is somehow "exposure".
The reality is you are ALWAYS "exposed" to TR failure - you just may be better positioned if you are say above 1000' AGL with 100 kts airspeed and a clear area in front of you. Anything else, and its not going to be your day.
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Old 29th Nov 2018, 10:39
  #864 (permalink)  
 
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Originally Posted by Non-PC Plod
Chopjock,

To reiterate what Double Bogey is saying - you seem to be hung up on the idea that getting VTOSS will somehow protect you from TR failure, and that being under this speed is somehow "exposure".
The reality is you are ALWAYS "exposed" to TR failure - you just may be better positioned if you are say above 1000' AGL with 100 kts airspeed and a clear area in front of you. Anything else, and its not going to be your day.
I was referring to VTOSS simply as a timing reference point for exposure comparison. I am aware if refers to single engine safety speed and will have little "keel" effect, but gaining forward airspeed sooner must be better than backing up with none for longer.
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Old 29th Nov 2018, 10:49
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Vtoss is a term that is only used in Category A procedures; it is used establish the Take-Off Distance Required. The definition of TODRH is:

The horizontal distance required from the start of the take-off to the point at which VTOSS, a selected height and a positive climb gradient are achieved, following failure of the critical engine being recognized at TDP, the remaining engines operating within approved operating limits.

Note.— The selected height stated above is to be determined with reference to either:

a) the take-off surface; or

b) a level defined by the highest obstacle in the take-off distance required.
The minimum climb performance required at Vtoss is 100ft/min.

Jim
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Old 29th Nov 2018, 11:04
  #866 (permalink)  
 
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Originally Posted by chopjock
I was referring to VTOSS simply as a timing reference point for exposure comparison. I am aware if refers to single engine safety speed and will have little "keel" effect, but gaining forward airspeed sooner must be better than backing up with none for longer.
So Chopjock, the pilot flies your ‘corner’ departure, just clears the stadium roof then 30seconds in at 60kts and 300ft still at high power has a tail rotor failure, he’ll be performing some form of emergency night autorotation onto dark roads and houses vs some form of vertical descent potentially into the lit stadium. Not a lot in it, both horrendous situations.

However had an engine failed instead which statistically is 1000 times more likely according to JimL’s certification stats, he would have a) (corner departure) collided with the stadium, or b) (Cat A) landed back onto the take-off spot without incident.
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Old 29th Nov 2018, 11:13
  #867 (permalink)  
 
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The AAIB Report tells us when the failure occurred and generally how it happened so we can roughly guess as to the rate and extent of pedal travel and time from liftoff that the Pilot lost control of Yaw.

Perhaps applying that information to Dash and Climb method that is being debated.....to get a good guess at what point the loss of yaw control would occur and thus make an assumption as to what forward speed and height the aircraft would have be at.....would be an interesting comparison to what did happen.

My bet is it would have be at a low height at a fairly low airspeed and probably. not clear of obstacles.....which would be a very bad situation to deal with.

We have to include the take off to a hover, the time required to hover back as far as possible, the time to point the aircraft to the takeoff heading, then accelerate towards the obstacles, hit some speed at or slightly above Translational Lift speed, then rotate the nose upwards, and climb until reaching a safe height above the obstacles.....then lower the nose and accelerate to Vy.....and of course all of the pedal movements that would be required in the process.

What if the yaw control failure happened while in the hover maneuvers prior to start of the take off run?

Anyone care to take a whack at that?
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Old 29th Nov 2018, 11:31
  #868 (permalink)  
 
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SAS

I think preying to whatever God tickles your fancy is the correct answer for almost ever version being discussed
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Old 29th Nov 2018, 11:54
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I would like to have a go at this in a Sim....and see how different scenario's would play out.

Two key issues to me are reaction time and what the initial Pilot action was....and how the aircraft was moving and reacting to the response made.

If the Collective had been put full down almost immediately.....and the nose lowered....would there have been a different outcome (not necessarily a pretty one).

Likewise....had the landing gear been down the whole time....how would that have affected the outcome of any less than controlled impact.

Early on in this thread I asked the question.....do we cause ourselves problems with all the various profiles as compared to the days when we flew the aircraft based upon all engine performance.

That was meant to ask a question similar to what Chopjock is going on about today.

I posed the question by asking if an old fashioned Confined Area Takeoff (Towering Takeoff) would not have been better than the Profile flown by the Pilot in the accident.

I was suggesting the Stadium is just a confined area....and if we did not bind ourselves to the now required profiles....would the outcome have been better in this case.

I reckon the Towering Takeoff method would in some regards not be that much different than the Rearwards Takeoff that was performed except for going vertical and losing visual contact with your Rejected Landing area.

The height required would be less than that reached by the aircraft....but not much.

The basic fact remains....this was a very difficult failure to define quickly (as to cause of the rotation) but the Pilot response would be too reduce Collective and lower the pitch attitude to obtain some forward airspeed.

If the Tail Rotor had a full stroke input....at zero airspeed (or nearly zero), the failure would very difficult to deal with.

One thing for sure is none of us....none.....ever want to be in the situation that this Pilot was that night.

What is important now is to learn as much as possible from this tragedy.

Discussions like this one is part of that process.

We may poke fun at each other on occasions...and even take objection to some things said....but in the end discussion, debate, and even argument can be productive.
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Old 29th Nov 2018, 13:50
  #870 (permalink)  
 
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SALESS,

"If the Collective had been put full down almost immediately.....and the nose lowered....would there have been a different outcome (not necessarily a pretty one)."

I think - maybe, .....but what you are asking is probably beyond any reasonable expectation of human performance. I tried what I think is the closest approximation available in the 169 simulator, which is the TR driveshaft failure in a similar position. But - knowing exactly what was going to happen and when, in the daytime, over a clear runway, I still was too slow at the first attempt, and crashed. I managed it second attempt. You would have to be superhuman to react quickly enough in the real (unexpected) situation.
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Old 29th Nov 2018, 13:58
  #871 (permalink)  
 
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Another method would have another pilot/person apply full pedal and hold it at full extension.....and see how that worked.
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Old 29th Nov 2018, 14:00
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REMINDER

Intrim AAIB report 14 Nov
Extract
Ongoing investigationThe cause of the apparent loss of yaw control has yet to be determined.
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Old 30th Nov 2018, 05:11
  #873 (permalink)  
 
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Failure ?

Originally Posted by SASless
The AAIB Report tells us when the failure occurred and generally how it happened
Unless I missed something the AAIB report does not tell that a failure occurred...
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Old 30th Nov 2018, 06:36
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Originally Posted by Hughes500
SAS

I think preying to whatever God tickles your fancy is the correct answer for almost ever version being discussed
Preying on anybody or anything would appear to be a waste of time. How exactly does one prey on God - an imaginary figure? Pray do tell.....
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Old 30th Nov 2018, 11:37
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Originally Posted by pilotmike
Preying on anybody or anything would appear to be a waste of time. How exactly does one prey on God - an imaginary figure? Pray do tell.....
Sarcasm perhaps @pilotmike ?

Last edited by 500e; 30th Nov 2018 at 11:48.
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Old 30th Nov 2018, 11:47
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Unless I missed something the AAIB report does not tell that a failure occurred...
Yes you missed something....other posters have quoted the AAIB several times.

The AAIB states it is continuing to investigate the apparent loss of tail rotor control.

They do not categorically state there WAS a Tail Rotor Control failure that caused the accident.

Combine the AAIB statement with the Video's that are available and one can easily assume a Tail Rotor malfunction of some sort occurred.

Did the AAIB not state in its Report that the aircraft was responding correctly to Yaw Inputs by the Pilot until the onset of the yawing?

Then add in to your consideration of the AD:s that were issued re the Tail Rotor Control Assembly and ask yourself why that happened very shortly after the accident.

Yes....I would say you have missed something.
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Old 30th Nov 2018, 12:36
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...with no advanced warning, he felt the nose of the helicopter drift right. He initially corrected with left pedal; however, the nose continued to drift right.

This is very similar to what AAIB is describing, but with other words taken from one of the many investigation reports addressing unanticipated yaw events. A failure cannot be ruled out but is not mandatory to explain the accident.
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Old 30th Nov 2018, 13:09
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Quick question without wishing to draw any conclusion but picking up on what AMDEC has highlighted - without a physical failure/restriction would a LTE event look somewhat different that what is seen in the videos?
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Old 30th Nov 2018, 13:10
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You would expect it to recover in the descent rather than keep yawing through several revolutions
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Old 30th Nov 2018, 13:19
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Originally Posted by SASless
Another method would have another pilot/person apply full pedal and hold it at full extension.....and see how that worked.
Agree - it would be interesting to see if that was even worse than having zero rotor thrust -Just wondering whether you can get negative pitch on the tail rotor at extreme pedal inputs?
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