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Fukushima Prefecture AW139 crash land, no immediatefatalities

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Fukushima Prefecture AW139 crash land, no immediatefatalities

Old 12th Feb 2020, 12:52
  #81 (permalink)  
 
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Might as well be Greek to me!

The photo certainly shows some real interest in the Tail Rotor Drive Shaft doesn't it!

Any other evidence....photos, news articles, that point to that as being the cause?
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Old 12th Feb 2020, 12:54
  #82 (permalink)  
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Originally Posted by SASless View Post
Might as well be Greek to me!

The photo certainly shows some real interest in the Tail Rotor Drive Shaft doesn't it!

Any other evidence....photos, news articles, that point to that as being the cause?
I believe there was another photo, I sent you a message on your phone.
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Old 13th Feb 2020, 07:20
  #83 (permalink)  
 
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Google translate on the article refers to a broken TRDS, but also says that part was missing?
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Old 13th Feb 2020, 22:24
  #84 (permalink)  
 
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Or was it a Sea King?
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Old 14th Feb 2020, 11:38
  #85 (permalink)  
 
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I proposed entering autorotation, pulling the engines to "Off", and landing with no engine power going to the drivetrain and a near zero groundspeed, saying I felt that would be far safer, smarter, and have a much better outcome.....

SAS you are so right!! Been there!
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Old 27th Feb 2020, 19:38
  #86 (permalink)  
 
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Am I am translating this correctly, Japan Transport Safety Board published this two days ago:
Unfortunately I cant post the link
TRDS pieces were found 1.5 km from landing site and they suspect that MRB collided with TRDS.
Is there any experience pilot to clarify what is the regime/Nr drop which could get blade to flex that much?
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Old 28th Feb 2020, 15:36
  #87 (permalink)  
 
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Wowsers!!!

On 25th February, JTSB released a press release which indicates the cause of the accident was fracture of the tail rotor drive shaft by contact with a main rotor blade. The shapes of the dent on the tip of the contacted main rotor blade and a fractured segment of the tail rotor drive shaft found apart from the accident site matched each other.
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Old 28th Feb 2020, 16:08
  #88 (permalink)  
 
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I recently experienced bio-mechanical feedback aka collective bounce in an AW-139 due to a sudden downdraft while I had the collective trigger pulled. I could absolutely believe the oscillations rapidly progressing to the point where the MR could flex down enough to hit the tail boom. If these guys were in heavy turbulence..
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Old 29th Feb 2020, 02:08
  #89 (permalink)  
 
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The sort of stuff you see on a certification flight, where they are still trying to figure out rotor dynamics, but the 139 is a proven 20 year old mature design. No “Bollettino tecnico” from Leonardo, so still a story to tell, I doubt there is a design issue. The last 2 minutes of FDM could be interesting.
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Old 29th Feb 2020, 16:49
  #90 (permalink)  
 
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I am curious to know how this was possible??? We all fly with strong wind or turbulence. Now if they decide to fly under severe turbulence,it is a different problem. I am curious to know what the FDR is gone say and what wind conditions they had, it does not make sense.
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Old 29th Feb 2020, 19:29
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Well here’s to hoping they were just using the nearest ridge line to embellish on the “light hearted” joke made in the back.
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Old 1st Mar 2020, 08:32
  #92 (permalink)  
 
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This picture of the TR shaft is interesting... What has made the ”clean cut” on the left end of the TR shaft? The MR has most likely caused the right end damages...but....🤔 Btw. The GPS antenna is located just above the left cutting point of the TR shaft...🤔

Last edited by Search&Rescue; 1st Mar 2020 at 09:12. Reason: Additional information.
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Old 1st Mar 2020, 09:10
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GPS antenna located above the TR shaft.
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Old 1st Mar 2020, 14:02
  #94 (permalink)  

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I can imagine a scenario where the damaged section of the driveshaft cover was pressed downwards onto the shaft, a score line could easily be formed, such that the shaft broke cleanly across it. These driveshafts are lightweight by design and it wouldn't take much damage to cause it to shear.

I consider myself lucky to have escaped an inclined driveshaft failure on an S-76 when an inadequately secured part of the wiring harness contacted it (a maintenance error). As it happened, it involved the wiring to the TGB chip detector and that shorted out, putting on the chip warning light. I put out a Pan call and inside two minutes I was on the ground at the minor airfield I just happened to passing and talking to. Even by then, although the wiring wasn't heavy in weight, it had badly scored the shaft, which had to be scrapped.
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Old 1st Mar 2020, 14:36
  #95 (permalink)  
 
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It takes very little to fatally score a drive shift.

Having flown the Chinook with what seems miles of the things....every four hour maintenance break or routine inspection found a crew member and pilot on hands and knees inspecting the Synchronization Shaft (the long multi-sectioned shaft that connects the two Rotor systems together) and running bare hands underneath the shaft and into the coupling wells looking for FOD.

Failure of that shaft was invariably fatal.

I once had an Engineer "lose" his rubber covered flashlight (Torch) inside my S-58T.

During a morning (in the daylight) Daily Inspection I found it for him by peering back into the dark of the engine compartment and seeing a bright line running around the shaft....with a flashlight switch assembly laying atop the shaft.

Had that shaft failed during the previous night's flying....it would have been curtains for us I am. quite sure...Winter, stormy seas, very early days of the Ninian Field being under construction.

I kept the shaft as a souvenir for years.

Keeping a sharp eye on Drive Shafts can be a life saver....that and doing a detailed inspection anytime there is suspicion or suggestion something might be wrong.

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Old 1st Mar 2020, 23:23
  #96 (permalink)  
 
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Originally Posted by SASless View Post
It takes very little to fatally score a drive shaft.
One dark and stormy night (as were all winter nights on the Brent Field) I chanced the first landing on a new trolley on the Treasure Finder, which put the front of the 212 out over the edge of the deck. During shut down there was a hefty gust of wind which rocked the slowing blades enough for the TR Drive Shaft to be cut through by the tip of one blade. The cut through the drive shaft was as neat as if it was done on a bench with a fine saw, yet there was not a mark on either blade tip.

If something caught on the 139 TRDS it wouldn't have taken much to weaken and sever the shaft IMO.
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Old 2nd Mar 2020, 00:33
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Ouch...
The morning DJ on 2-MMM, Doug Mulray, said "Poor old Polair Two - last night they were practising emergency landings, and he cut his own @rse off!"
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Old 2nd Mar 2020, 01:15
  #98 (permalink)  
 
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It takes very little to fatally score a drive shift.
Friend cranked up a 212, took off, experienced a high freq and promptly landed. A screw driver had been left in the tail rotor tunnel and in that short time had cut half way through the shaft.
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Old 2nd Mar 2020, 06:49
  #99 (permalink)  
 
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Originally Posted by Ascend Charlie View Post

Ouch...
The morning DJ on 2-MMM, Doug Mulray, said "Poor old Polair Two - last night they were practising emergency landings, and he cut his own @rse off!"
There might be several reasons for that incident if the intention was a ”all the way down” autorotation... e.g. that the pilot never levelled the helicopter before touchdown... if the tailguard is touching the ground first; the tailboom will ”jump up” and the MR will cut the boom immediately...
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Old 2nd Mar 2020, 07:56
  #100 (permalink)  
 
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On that prang they didn't lower the collective on touchdown and the aircraft briefly got airborne again. When the aircraft touched down the 2nd time it rocked forward and in doing so the MRB chopped the tail boom. Two years later they sunk it properly off Sydney heads after an engine failure.
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