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UK AAIB (H) Jan 2020

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UK AAIB (H) Jan 2020

Old 10th Jan 2020, 20:52
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UK AAIB (H) Jan 2020

EC135 MR actuator tie-bar fracture while lifting off, lands but heavy damage. Link

A109E loses co-pilotís door window on test after it was replaced. Link

280FX overshoots off steep approach, ends up in quarry it then has difficulty climbing out of. Link
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Old 13th Jan 2020, 11:36
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How 'catestrophic' would it be if

EC135 MR actuator tie-bar fracture while lifting off, lands but heavy damage. Link

occurred in the cruise? Total loss of control?

Cant help thinking this would have been awkward if it had not been at only 4ft ?
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Old 13th Jan 2020, 12:13
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Originally Posted by AnFI View Post
How 'catestrophic' would it be if

EC135 MR actuator tie-bar fracture while lifting off, lands but heavy damage. Link

occurred in the cruise? Total loss of control?

Cant help thinking this would have been awkward if it had not been at only 4ft ?
My thoughts exactly - I'm familiar with similar incidents that did occur in the cruise and the outcomes were bad
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Old 19th Jan 2020, 17:05
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As we were just about to go offshore, the likelihood of knowing the cause would never of happened and there would be a hundreds of aircraft flying around with potentially the same defect. We'll take this for the TEAM..... Fly safe
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Old 19th Jan 2020, 19:02
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Originally Posted by DEGRADE View Post
As we were just about to go offshore, the likelihood of knowing the cause would never of happened and there would be a hundreds of aircraft flying around with potentially the same defect. We'll take this for the TEAM..... Fly safe
It is fairly deep around there, isnít it Degrade!?
Cheers
TeeS
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Old 19th Jan 2020, 22:48
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Originally Posted by AnFI View Post
How 'catestrophic' would it be if

EC135 MR actuator tie-bar fracture while lifting off, lands but heavy damage. Link

occurred in the cruise? Total loss of control?

Cant help thinking this would have been awkward if it had not been at only 4ft ?
Since it was the cyclic pitch actuator that let go, it would be a short but memorable flying display followed by a cancelled late lunch.
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Old 20th Jan 2020, 20:31
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"the cyclic pitch actuator that let go" or maybe one of the three double actuators

1x10^-9 is a bogus fantasy as we see with the terrible toll this delusion results in

would have been a wild ride but that sort of thing has been survived before (swash plate from 2 grand)
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Old 20th Jan 2020, 21:24
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"the cyclic pitch actuator that let go" or maybe one of the three double actuators
yes - all required to control pitch roll and collective on an almost rigid head. What would your solution be on an aircraft this weight with this head - regardless of number of engines?
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Old 20th Jan 2020, 22:07
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212: "What would your solution be"
I would try and do what this pilot did and have it happen at 4ft.

Engines?!?!?! overrated !!! better to put the effort into important real things
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Old 20th Jan 2020, 22:16
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Originally Posted by AnFI View Post
212: "What would your solution be"
I would try and do what this pilot did and have it happen at 4ft.

Engines?!?!?! overrated !!! better to put the effort into important real things
I meant design - not dealing with the event.
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Old 21st Jan 2020, 16:43
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Originally Posted by 212man View Post
I meant design - not dealing with the event.
Simplicity focus margin . looking at the diagram the component is excessively complex not really fit for 10^-9 servos to be dependant on imo
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Old 21st Jan 2020, 22:26
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We await your brand of simple yet effective servos to hit the helicopter market AnFI so we can marvel at your brilliance............
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Old 22nd Jan 2020, 08:57
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Engines?!?!?! overrated !!! better to put the effort into important real things
Well having two engines can prevent some ditchings....
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Old 4th Feb 2020, 17:13
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"We await your brand of simple yet effective servos to hit the helicopter market"

I think Bell, Robinson and others make a historically reliable single hydraulic servo arragement.
Certainly duplication of those would be unwarrented on a weight/reliability/cost/complication consideration.
(and MD helicopters achieve 100% reliabilty of servos by not having any)

One of the odd things about the regulation is that it pushes people into duplication of the servos without much consideration for the reliability of the common connection to them. for example imagine 10^-14 heavy, complex and expensive items held together by 10^-7 items (as in this case?)

Last edited by AnFI; 4th Feb 2020 at 17:17. Reason: adding MD
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Old 4th Feb 2020, 18:47
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Single servos are acceptable on an aircraft where control feedback forces are low enough for the pilot to fly in full manual control. This is definitely not the case for larger helicopters. I wouldn't want to fly any aircraft knowing that if the single hydraulics system failed I would be another passenger - I've had too many hydraulic failures in the past; some of them the result of a simple crush washer leak or flexible hose failure.

Also, without servos there can be no SAS or autopilot. Having been required to operate totally unstabilised, untrimmable/"floppy stick" helicopters IFR/IMC in the past (and properly trained to do it) I have no pressing desire to have to do so ever again.
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Old 4th Feb 2020, 21:52
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And, whilst there will always be some single points of failure possible in any helicopter, where duplication is achievable without enormous weight penalty, it is desirable to provide redundancy and also required for IFR certification.

Much safer than having the single point of failure as the over-confident pilot who may make all sorts of errors of judgement and poor decisions leading to serviceable aircraft getting wet.
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Old 8th Feb 2020, 21:54
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Crab: "where duplication is achievable without enormous weight penalty, it is desirable to provide redundancy"
good point, quite right.
It is about measuring how worthwhile it is. Not ONLY in terms of weight, which is important.
A helicopter carrying only safety equipment is doing nothing useful. Duplication is a safety strategy that needs justification.
(carrying a defribulator is a safety strategy, in an A380 is probably justifiable, in a 139 probably not, kinda obvious really)

Multi Pilot: sure quite right too, much higher yeilding safety contribution.
Also saves aircraft from sheer incompetant/arrogant handling mishaps...
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Old 9th Feb 2020, 11:09
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You should know that even in multi pilot ops a poor cockpit gradient or absence of CRM can still cause problems - you know the sort of thing where an ego-driven PIC makes a series of poor decisions that the hapless co-pilot or pilot under training doesn't feel he/she can challenge..............and suddenly they are bobbing in the oggin......
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Old 9th Feb 2020, 21:24
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insincere ibberish veiled insults unmoderated, makes you sick.
Nothing to do with pointless servo duplication.
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Old 9th Feb 2020, 21:32
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Originally Posted by AnFI View Post
insincere ibberish veiled insults unmoderated, makes you sick.
Nothing to do with pointless servo duplication.
AnFI you are treading on very thin ice with your comments here and elsewhere on moderation. There are many posts that get moderated that you would have no knowledge of: just because it is not always made to your demands is not cause for your raising it online.

Please do not break the T&Cs that you agree to when posting here; no more comments on moderating.
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