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Old 29th Apr 2016, 22:13   #81 (permalink)


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Originally Posted by Daylite View Post
Speaking with chc technical department, it now seems the gearbox in the aircraft was only changed yesterday.
CHC are saying that it was changed in January:

http://uk.reuters.com/article/us-norway-crash-idUKKCN0XQ15K
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Old 29th Apr 2016, 22:15   #82 (permalink)
 
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Any ATC transcript?
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Old 29th Apr 2016, 22:21   #83 (permalink)
 
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electrotor
I stand corrected in my use of loose terminology. Perhaps it would have been more correct to state that the weight of the aircraft is primarily supported by the top bearing in the gearbox casing and as has been previously demonstrated, it is possible for the rotor shaft to pull through the bearing and depart given certain fault conditions.

This accident bears remarkable similarities to the G-REDL incident where the main rotor also departed from the helicopter. I would not be surprised if a similar failure mechanism was found. Height at which the incident occured is almost identical and apparently there was no warning before the main rotor broke away.
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Old 29th Apr 2016, 23:02   #84 (permalink)
 
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I wonder did anyone monitor the last radio transmissions to see if the pilot issued a Mayday alert as was the case for G-REDL in 2009 when metal particles in the gearbox caused it to fail and shear the rotor head.
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Old 30th Apr 2016, 00:22   #85 (permalink)
 
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Helicopters have some graceless failure modes.
Should there be a provision for an emergency parachute, such as offered on some light aircraft, or is that impracticable for this size vehicle?
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Old 30th Apr 2016, 00:28   #86 (permalink)
 
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MR imbalance

Blades all look attached, however if a blade failed in the driving region and separated...
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Old 30th Apr 2016, 00:38   #87 (permalink)
 
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Originally Posted by JohnDixson View Post
... so what were the 5 maintenance flights for? I made the assumption they were MTF's because Jimf671 wrote that they were short. ...
That was from flightradar24. There are some anomalies in the way that flightradar24 records flights but looking at the detail there is definitely a record of 3 short flights that are 13 to 16 minutes long and are circuitous around local fjord and nearby islands. The first is 1129h 26th, second 0643h 27th, third 1224h 27th. The first has a routine flight number and so may be a RTB after normal departure. No other flights are shown during that 25 hour period.
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Old 30th Apr 2016, 02:13   #88 (permalink)
 
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Next Theory

Jim, with the gearbox change being accomplished in January, it looks like it's time to wait for the sharp eyes to look at what came down with the rotor head and how/where it failed structurally, as well as determining what, if anything, the main blades hit prior to the head separation. Time for the accident investigation pro's and the OEM design/test people to look at the evidence. Still would be of interest to know what the short flights were all about.
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Old 30th Apr 2016, 03:03   #89 (permalink)
 
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Originally Posted by JohnDixson View Post
Jim, with the gearbox change being accomplished in January, it looks like it's time to wait for the sharp eyes to look at what came down with the rotor head and how/where it failed structurally, as well as determining what, if anything, the main blades hit prior to the head separation. Time for the accident investigation pro's and the OEM design/test people to look at the evidence. Still would be of interest to know what the short flights were all about.
HUMS parameters just beyond limits? Couple 'quick fixes' to get it within limits perhaps. Who knows.
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Old 30th Apr 2016, 03:08   #90 (permalink)
 
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It is what it is and it's out there on a public website. What it means is for the professional head scratchers.
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Old 30th Apr 2016, 03:39   #91 (permalink)
 
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For what it is worth.

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Old 30th Apr 2016, 04:23   #92 (permalink)
 
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ETUDIANT - Think about where you would mount the parachute on a light aeroplane ....- away from the rotating parts, so whether the chute is deliberately or inadvertently deployed, it can work without interference.
I cant think where you could mount a safety parachute on a helicopter where it is not going to cause a catastrophic failure if inadvertently deployed, and where it is going to be unimpeded by rotating parts if you want to deliberately deploy it (in all circumstances except complete detachment of the main rotor head, which remains an extremely rare occurrence)
So - chutes are a fairly impractical proposition for helicopters.
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Old 30th Apr 2016, 04:51   #93 (permalink)
 
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How about under a suitable faired structure where the 'chinamans hat" is currently atop the jesus nut?

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Old 30th Apr 2016, 05:25   #94 (permalink)
 
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How about under a suitable faired structure where the 'chinamans hat" is currently atop the jesus nut?

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For F*cks sake! That is the stupidest post I have seen in a long time.
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Old 30th Apr 2016, 05:40   #95 (permalink)
 
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Thanks for your informative input.

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Old 30th Apr 2016, 05:45   #96 (permalink)
 
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Having just watched the video above and I realize I'm asking for speculation, but seeing the video of the rotor head falling and the still pictures would we assume that it failed where the bevel gear is welded to the m/r shaft?
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Old 30th Apr 2016, 05:52   #97 (permalink)
 
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On the EC225 all lift forces are transmitted to the airframe via the bearing housing of the MRH mast not the MGB. 3 suspension bars transmit the lift forces from the mast to the airframe. One of the suspension bars can be clearly seen in the photograph of the detached MRH.
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Old 30th Apr 2016, 06:03   #98 (permalink)
 
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OK, so which actual part would fail that would cause such a clean (relatively) break that would allow the entire rotor head and blades to depart seemingly undamaged.

Again....realizing that it would be speculation, but from someone who has knowledge of how the system is designed ( I'm not an EC/Airbus guy)
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Old 30th Apr 2016, 06:20   #99 (permalink)
 
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Rest in Peace Passengers & Flight-Crew, another very sad day in the Rotory World
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Old 30th Apr 2016, 06:31   #100 (permalink)
 
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Originally Posted by Outwest View Post
OK, so which actual part would fail that would cause such a clean (relatively) break that would allow the entire rotor head and blades to depart seemingly undamaged.
The fact that the main rotor has been recovered more or less intact should mean that the cause of the failure gets established pretty quickly. I wouldn't be surprised if we see an AD within the next few days.
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