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Helicopter down outside Leicester City Football Club

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Helicopter down outside Leicester City Football Club

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Old 6th Nov 2018, 10:20
  #601 (permalink)  
 
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Which maintenance organisation would have been looking after this helicopter?
Sloane, I believe.
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Old 6th Nov 2018, 10:23
  #602 (permalink)  
 
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Originally Posted by silverelise
These two sentences contradict each other.
No they don't. TR control malfunction you should still be able to land the helicopter at a place of your own choice, without any particular urgency, and without putting a scratch on the aircraft. TR drive malfunction is far more serious, with far less options available, which can very quickly lead to loss of control.
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Old 6th Nov 2018, 10:30
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Originally Posted by gulliBell
No they don't. TR control malfunction you should still be able to land the helicopter at a place of your own choice, without any particular urgency, and without putting a scratch on the aircraft. TR drive malfunction is far more serious, with far less options available, which can very quickly lead to loss of control.
I would tend to disagree. A TR Servo problem could include an uncommanded full input in either direction, which is the equivalent of applying full yaw pedal - which is very much like what we see in this incident. I fail to see how that can be considered 'controllable'. The S92 referred to earlier may have had a similar outcome if not a few feet above the deck.
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Old 6th Nov 2018, 10:30
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This is now applicable to AW189 Fleet too.
I understand this would not normally be disturbed during maintenance.
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Old 6th Nov 2018, 10:34
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Gullibell - sorry bud but you are missing an important point. TR Control Malfunction leading to a minimum power hard over is almost the same as Drive Failure and will force an EOL in most types of helicopters. Obviously most types with duplex hydraulics have design features to try to avoid hardovers, but if an input lever detaches...….blades throw off pitch...…..bye bye anti-torque thrust!
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Old 6th Nov 2018, 10:39
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"s it me or is that wire locking incorrect in the pic above?"

I don't think so - looks as though the smaller bit on the end is part of the shaft and the big nut covered in blue is locked to it.
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Old 6th Nov 2018, 11:20
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Is it certain that the "in service event" referred to in the SB is the Leicester accident?
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Old 6th Nov 2018, 11:27
  #608 (permalink)  
 
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Originally Posted by hoodie
Is it certain that the "in service event" referred to in the SB is the Leicester accident?
It seems hard to imagine otherwise.

For info, in the S92 incident referred to above by simfly and me, from the report it says: " it yawed rapidly to the right, reaching a maximum rate of 30° per second. " Bear in mind it was 4 ft above the deck and landed after only 146° of yaw, imagine how it would have developed from the same position that Eric found himself in!!
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Old 6th Nov 2018, 11:31
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Originally Posted by Sandy Toad
This is now applicable to AW189 Fleet too.
I understand this would not normally be disturbed during maintenance.
Yes: 189-213
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Old 6th Nov 2018, 11:45
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Inquest Opens BBC News

https://www.bbc.com/news/uk-england-...shire-46107923

Last edited by nomorehelosforme; 6th Nov 2018 at 12:08. Reason: spelling
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Old 6th Nov 2018, 12:05
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From the AAIB site:


https://www.gov.uk/government/news/u...ccident-g-vskp
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Old 6th Nov 2018, 12:14
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Originally Posted by [email protected]
Bumpthump - at TDP, if using the AW confined area profile, the yaw offset to provide sight of the LS is taken out as the nose is pushed forwards to gain speed. thereafter it is as Shytorque says
Thank you.
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Old 6th Nov 2018, 12:25
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Originally Posted by Mitchaa
Trying to think of a way an installation maintenance error could be made here? The washer (140) on the wrong side of the bracket or incorrect wire locking so the nut isn't locked to the shaft?
My thoughts, and reading the wording of the inspection, makes me think that perhaps the safety wasn't there at all or failed, and the nut backed off completely. That of course would remove your pitch control completely

you would still have your T/R drive all the way thru this event, and that would explain the strike damage in the picture we debated earlier.
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Old 6th Nov 2018, 12:33
  #614 (permalink)  
 
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Is the Tail Rotor designed to go to neutral pitch or some position such as the BK is which uses counter weights?
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Old 6th Nov 2018, 12:51
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I would think most TR's would find their neutral spot. No idea what this TR assembly would do.
I look at item 90 as a part that might affect that point should it get cockeyed or jammed somehow once everything got loose. Pin 80 must get pinch fitted somehow under torque of the nut to prevent it from coming out under normal circumstances

No idea how it is put together though, so I'm only guessing
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Old 6th Nov 2018, 13:06
  #616 (permalink)  
 
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Mitch....we are talking about a 169....not a 92.

My question was very much Type specific.

How the Tail Rotor would react if this component came adrift would determine how the aircraft reacted to the failure.

Would the Servo(s) go hard over in one direction or another....or would there just be a loss of Pilot input and the Tail Rotor itself be free to find some position it liked?

Perhaps some Engineers that work on the 169 can advise us on that?
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Old 6th Nov 2018, 13:19
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Originally Posted by SASless
Mitch....we are talking about a 169....not a 92.

My question was very much Type specific.

How the Tail Rotor would react if this component came adrift would determine how the aircraft reacted to the failure.

Would the Servo(s) go hard over in one direction or another....or would there just be a loss of Pilot input and the Tail Rotor itself be free to find some position it liked?

Perhaps some Engineers that work on the 169 can advise us on that?
The nut in question is on the end of the pitch change shaft, after the pilot input and servo assy, so neither of these would be able to transmit any movement to the TR pitch.

Last edited by FlightSpanner; 6th Nov 2018 at 13:20. Reason: Spelling!
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Old 6th Nov 2018, 13:33
  #618 (permalink)  
 
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Thank You!

That is very helpful insight into the mechanism of how this thing might have failed.

What drove my question is the BK-117, for example, in the event of a loss of pilot input (linkage failure for example) the tail rotor has counter balance weights that are supposed to return the Tail Rotor to somewhat a neutral position rather than it being able to hunt for a position it likes which could cause severe handling issues.

I was curious if the 169 was similarly designed in some way.
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Old 6th Nov 2018, 13:35
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Originally Posted by Mitchaa
Yes, item 110 would have flapped loose of the TR Pitch shaft which means the TR pitch shaft would have been stuck in its last commanded position with no way to counter it?
Could stick, go to a designed position or zero pitch, sorry don't know the answer
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Old 6th Nov 2018, 13:59
  #620 (permalink)  
 
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General comment on servos:-
If the feedback fails then the servo will drive to the end stop.
Feedback is negative, it tells the servo when to stop.
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