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Video is very chilling, doesn't bare thinking about. I knew two pilots killed through MR separation in two separate accidents.
RIP to the crew and Pax. |
Originally Posted by REDHANDED
(Post 9361503)
I know, but it's not stopping accidents happening. The alerts are only as good as the algorithms used to set them. We need more data inputs from the manufacturers and operators to enable better alert thresholds to be set so that warnings can be actioned in good time. I question the manufacturers current advice on how to act upon warnings from the HUMS. It was wrong wrt G-REDW
If you have a rapid mechanical failure there is almost no chance of seeing a trend. |
In the picture, is that one of the transmission supports sticking up between blades?
(Edit) Looking closer in the high rez images, the entire swash plate is visible in one, and indeed the transmission support is poking up in another.... RIP those involved. Have way too many friends in the Norwegian sector... Not ready to lose a single one... |
YEP agree all roots are there, must be old age getting the better of the ole eyes
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Originally Posted by Max Contingency
(Post 9361552)
Professional helicopter pilots buy a ticket in the Great Gearbox Lottery every time we fly.
We have all heard of rotor head separation before but I believe that this is the first time it has ever been captured on camera. To see that rotor head, the size of a small house, rotating down without the rest of the aircraft sent a chill right down my spine. Yes the passengers would have been terrified but only the pilots would have known the absolute finality of what was happening. Made an entry in my diary, simply says: "Bugger" :( |
The swashplate and the main driveshaft are visible. If the MRH is fitted over the MRGB main drive shaft like the Sea King then that drive shaft has detached from the MRGB rather than the MRH detaching from MRGB. I.e. the pressure plate or upper securing nut. It is strange that there is no bolt evident on that support rod.
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In the top photo in post #141 four blades look relatively intact. One blade (the one pointing "down" is only partially there (you can see more spar than afterbody and ever then the blade is short). A blade failure could easily rip the rotor, swashplate etc. out of the aircraft relatively intact. It is possible, if not probable, that this could have occurred in a fuselage strike, but that amount of blade loss would easily rip the "rotor et al" out of the aircraft. That kind of failure is generally proceeded with a "bang." As to HUMS there are multiple cases (Bristow 76 as an example) where there was almost no warning of a catastrophic blade failure.
The Sultan |
I have to agree that the likelyhood is all persons were alive on the way down the report from LN-OPG which crashed in 1997 from a similar height and cruise speed after an MGB input shaft sheared. states everyone died in collision with the water...
It makes chilling reading and although a 332L1 the construction of main components is similar if not identical. I suggest some of the keyboard warriors read the report to answer some of the questions being raised here. https://en.wikipedia.org/wiki/Heliko...ice_Flight_451 |
Which picture are you seeing the swashplate in? I think I'm looking at the droop stop ring in the pictures above.
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Originally Posted by PhilJ
(Post 9361704)
Which picture are you seeing the swashplate in? I think I'm looking at the droop stop ring in the pictures above.
Zoom in and you see the swashplate. You can just make out the Pitch link attachment lugs. |
Originally Posted by 212man
(Post 9361659)
I'm pretty sure that anybody free falling 2000 ft would have a pretty good idea what happens next!
Poor guys.... |
From EC pilot training manual:
begin MAIN ROTOR HUB integral with the rotor shaft supports the rotor components ROTOR SHAFT driven by the MGB, supports the main rotor hub. FLARED HOUSING : transmit the aerodynamic force from a rotating part (rotor shaft) to a non-rotating part (fittings bolted on the fuselage) via 3 suspension bars. The splined end of the rotor shaft engages in the MGB second stage planet gear cage end If the visible bar on the picture is a suspension bar, thus, this bar has gone loose from the fuselage while remaining attached on the flared housing that I presume is under the visible swashplate. |
Originally Posted by The Sultan
(Post 9361668)
In the top photo in post #141 four blades look relatively intact. One blade (the one pointing "down" is only partially there (you can see more spar than afterbody and ever then the blade is short). A blade failure could easily rip the rotor, swashplate etc. out of the aircraft relatively intact.
If you watch the video of the falling rotor you will see that all 5 blades are there and seem to have still their full length. The Rotor is drifting down in balance. So in this accident this probably wasn't the case. |
on the subject of HUMS i'm glad to see my company checking after every flight. it takes 15mins to check. |
Originally Posted by How Nice
(Post 9361715)
You can see it on Tylermonkey's post (#141)
Zoom in and you see the swashplate. You can just make out the Pitch link attachment lugs. |
Henra
I was next to a helicopter running on the ground which let go an integral piece of a blade that took off the outboard section of the blade. The transmission was snapped in half and the rotor, mast, swashplate seperated climbed 100 feet and then came down not 30 feet from the ship. It happened so fast the pilot reported no vibration. When in flight the rotor was stable as it rotated around its new cg. The Sultan |
Originally Posted by PhilJ
(Post 9361743)
I think what you can see is the droop stop ring and the lugs are the top of the scissor link. Compare it to the cad model on page 6 posted by RVDT.
In the pic in post 140 you can see 2 lugs which wouldn't be possible from that angle if it were the droop stop ring. You can also see the outer race of bolts which look like part of the rotating swashplate. |
Originally Posted by Mitchaa
(Post 9361766)
Not a good idea DairyGround, the biggest annoyance of any HUMS systems is false alerts caused by poor instrumentation. You could potentially leave a decision to ditch a helicopter in the North Sea to the pilot having to make that call only to find out that an accelerometer had lost a little torque and created a jump in the data. Only proper analysis and cross comparisons on a ground station would give you this info. Real time monitoring like they do on fixed wing has been talked about for years now but always dismissed due to the potential pitfalls. The crew already have enough to concentrate on, never mind hundreds of HUMS parameters to add to that.
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Originally Posted by How Nice
(Post 9361772)
I'm not so sure. The lugs on the droop stop ring are 180 degrees apart and much closer to the centre line of the main shaft.
In the pic in post 141 you can see 3 lugs which wouldn't be possible from that angle if it were the droop stop ring. You can also see the outer race of bolts which look like part of the rotating swashplate. |
I lightened up the image some more . . .
http://i86.servimg.com/u/f86/11/94/64/62/hub310.jpg http://imbo.vgtv.no/users/bt_/images...]=1800x1012q50 |
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