EC225 crash near Bergen, Norway April 2016
HC,
Conspiracy Theory a Hobby of yours now days since you have retired?
...in fact anything that could reflect on things Norwegian, they are strangely silent....
Conspiracy Theory a Hobby of yours now days since you have retired?
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from HC:
Also: Status of front suspension bar (missing or not), status of front attachment area - pins missing?, holding pin?, front bracket damage?
.....crickets.
And yet on some of the basics such as the maintenance history, component hours, history of HUMS data, in fact anything that could reflect on things Norwegian, they are strangely silent even though this info must surely be readily available just a day or two after the accident
.....crickets.
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I haven't looked at this topic for a few weeks, so hopefully I'm not about to repeat something which might already have been raised by others. As someone with thousands of hours flying the EC225, I know that there is a chip detector spring-loaded toggle switch above the pilots' heads. Moving it one way tests all chip detectors, both for the engines and gearbox. While holding the switch against its spring you see in sequence "Chip1" for engine 1, "Chip2" for engine 2 and "Chip" for the gearbox, all showing on the VMS display panel. This test gets done before every flight. Moving it the other way in flight would put a high voltage electric pulse through the very smallest (hair fine) metal particles on the detectors and burn them off. Two such "fuzz burns" are allowed in flight, after which if it's a gearbox "Chip" warning a landing must be made as soon as possible e.g. on the nearest available helideck offshore. I've only ever had a "Chip 1" in flight and I brought engine 1 back to idle in the cruise, to minimise further possible damage. The particle was found to be negligible and the engine was returned to service. With the removal of the magnets from the gearbox after the REDL disaster, I would hope that the slightest particles from wear or spalling in the epicyclic gears at the top of the gearbox would be detected long before any risk could arise. But this doesn't seem to have been the case in Norway. Yet photographic evidence and some opinions suggest that there was wear. In which case why weren't particles being detected during several hours of flight before the rotor head came off?
The ability to distinguish between harmless "nuisance" debris (or fuzz) and larger debris that indicates a more serious problem is very important. Every engine and gearbox continually generates nuisance debris throughout its life from metal surface contacts in rolling element bearings/gears/splines/etc. Bearings/gears/splines tend to generate a greater amount of nuisance debris when new, and much less after they have been run-in.
The sensing end of a magnetic chip detector is commonly positioned so that it has maximum exposure to the passing lube oil flow, and ideally in a location where the denser ferrous metal debris particles naturally tend to separate from the oil flow. Chip detectors are often positioned inside (the upstream side) of a filter screen at the oil pump pick-ups, which further helps to separate debris particles in the lube oil flow. The advantage of this filter screen and chip detector arrangement is makes things easier for techs to perform an inspection after there is an indication from the chip detector. They can first remove the chip detector to see exactly what size/shape of debris has accumulated on the magnet rings. They can also remove the filter screen to look for larger debris.
Perhaps you are thinking about resistors in series? I am thinking about a resistor in parallel within the body of the detector.
The chip detector has magnetic sensor rings with a short gap between them.
Some maintenance procedures call up regular checking with a "test piece".
A surprising number of maintenance manuals don't.
Just saying.
Chip Detector Resistor
"I am thinking about a resistor in parallel within the body of the detector."
Most chip detectors on newer rotorcraft incorporate resistors in parallel with the detector circuit to provide an indication of an open circuit. Without this function a broken wire to the detector would not be identified in flight.
Most chip detectors on newer rotorcraft incorporate resistors in parallel with the detector circuit to provide an indication of an open circuit. Without this function a broken wire to the detector would not be identified in flight.
"I am thinking about a resistor in parallel within the body of the detector."
Most chip detectors on newer rotorcraft incorporate resistors in parallel with the detector circuit to provide an indication of an open circuit. Without this function a broken wire to the detector would not be identified in flight.
Most chip detectors on newer rotorcraft incorporate resistors in parallel with the detector circuit to provide an indication of an open circuit. Without this function a broken wire to the detector would not be identified in flight.
(Or on the ground, either)
Tis not their job to satisfy your hunger for information...I am sure they will get around to reporting all that information when they put out a more substantive Preliminary/Interim Report.
This is true. However it is interesting to note what information has been leaked / drip fed, and what info has been withheld.
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This is true. However it is interesting to note what information has been leaked / drip fed, and what info has been withheld.
WHY?
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Re: SLB #1251.
The SKF procedure is for spherical rollerbearings. On normal roller bearings it seems that one flange is often pressed into place after spacers and roller are in place.
Strange that we have no leaked mintenance manuals for the gearboxes.
The SKF procedure is for spherical rollerbearings. On normal roller bearings it seems that one flange is often pressed into place after spacers and roller are in place.
Strange that we have no leaked mintenance manuals for the gearboxes.
it is interesting to note what information has been leaked / drip fed, and what info has been withheld.
Have you considered a leaky faucet might have been tightened up?
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Its a legal requirement when taking part in an investigation not to speak about any part of it to anyone outside the investigation. People leaking information do not help the investigation in any way. It is very frustrating to be on the inside of an investigation and seeing some of the rubbish that is put forward by armchair investigators and the media, but having the professionalism not to break the investigation rules. When the facts are fully known, they will be released.
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It is certainly pretty clear that the suspension bar theory still needs clarification. It still hasn't been ruled out as the primary causal event. I'm assuming they do not yet have enough evidence to stand up a chain of events and have decided to say nothing. Both Airbus and the AIBN have been very quiet since 1 June report and CHC have only mentioned the commercial aspects/redundancies.
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This seems like an interesting article: Airbus-sjef frikjente girboksen. 12 dager senere kom rapporten som indikerer det motsatte - Tu.no
Could someone please help translating the article and linked document?
Could someone please help translating the article and linked document?
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Because for example the hours on the epicyclic since overhaul must be known but it's not been reported. Ditto the HUMS history. Maybe the relevant HUMS history is zero (probably not!) in which case say so. What maintenance activities relating to the struts? Must be known, but secret. Exactly what bits of struts were found where (ie what remained attached to the transmission decking, what was attached to the free flying bit. This must be known but the release of info on this subject has been cryptic.
WHY?
WHY?
Seeing in the light of how the bereaved from former accidents
are feeling towards the openness of the investigation, it is high time
that there is put some pressure on it!
Not to leak, but to be frank, humble and correct in the statements made.
Up until now I have found several contradictions in the info stated by CHC
Also the need to have a public advisor present, and thus is hesitating to
the most extent to confirm or make clear any of the questions asked by the press.
This is not alone only the case with CHC, but also Statoil and
as well AH.
Using Google Chrome translate feature reveals:
The highlights are mine.
Note that the box was overhauled/repaired by AH, if the text is correct.
SF is composed of representatives from the government, helicopter operators, oil industry, Avinor, unions and others involved in the offshore sector.
They have met three times after the accident with EC225 helicopter that crashed outside Turøy 29 April.
In the second extraordinary meeting on 20 May, attended by several representatives from Airbus Helicopters, including their security chief.
According to the minutes , he ruled out that events are similar in character to the accidents in 2009 and 2012.
In 2012 an emergency landing two EC225 in the North Sea with wrecked Main Gear Box (MGB) with crack in the same place on the shaft.
In 2009 overthrew a AS332L2 after MGB failed due to fatigue fracture on one of the planetary gears in the second stage of the episyklisme module.
But in the interim report from the Accident Investigation Board Norway (AIBN) from June 1, it is pointed precisely at a similar fatigue fracture in one of the planet wheels of one of the planetary gears.
- Airbus Helicopters (AH) argues that it is not found traces of overheating in MGB. AH do not think the problem lies in the MGB, but must be found outside. That is why AH believes that one can not add design of MGB assumed that the helicopter should not be airworthy, according to the minutes of helicopter safety forum.
At this time argued helicopter manufacturer remains that mistake by one of the hangers, specifically attached to the MGB suspension bar, was a likely trigger for the main rotor loosened.
In the minutes it emerged that Norwegian expertise find it difficult to understand that too much torque on fixing bolts to support braces on MGB should be able to cause a break in the support structure.
- This position Airbus Helicopters had taken, was solely founded on proprietary research. We are critical of the factory as much has been leaning in one direction instead of being more open in an early exploration phase, says SF leader Anders Røsok to TU.
TU has asked Airbus Helicopters question whether they still believe that the primary cause of Turøy accident is outside the MGB.
A spokesman for the helicopter manufacturer says the TU that the only thing they will be quoted on now, is that they work closely with the Norwegian Accident Investigation Board and that they do not rule out some causes.
In conversation also shows that Airbus did not entirely agree with SF-abstract. Their version is that the message on May 20 was that it was too early to draw parallels to the 2009 accident, not to categorically reject any similarities.
TU mentioned last week that the reconditioned main gearbox, which was installed in the accident helicopter on January 17, was subjected to "rough treatment" and had to return to the workshop before installation.
This is among several things AIBN now look more closely at, and which also was the topic of helicopter forum, shows the minutes.
- SF wanted to know what was done by transport damage in Australia. AH explained the process when this transmission came into the AH for repair. They were further asked whether it was possible to see the strip down the report by the overhaul of the MGB. AH would check up.
They have met three times after the accident with EC225 helicopter that crashed outside Turøy 29 April.
In the second extraordinary meeting on 20 May, attended by several representatives from Airbus Helicopters, including their security chief.
According to the minutes , he ruled out that events are similar in character to the accidents in 2009 and 2012.
In 2012 an emergency landing two EC225 in the North Sea with wrecked Main Gear Box (MGB) with crack in the same place on the shaft.
In 2009 overthrew a AS332L2 after MGB failed due to fatigue fracture on one of the planetary gears in the second stage of the episyklisme module.
But in the interim report from the Accident Investigation Board Norway (AIBN) from June 1, it is pointed precisely at a similar fatigue fracture in one of the planet wheels of one of the planetary gears.
- Airbus Helicopters (AH) argues that it is not found traces of overheating in MGB. AH do not think the problem lies in the MGB, but must be found outside. That is why AH believes that one can not add design of MGB assumed that the helicopter should not be airworthy, according to the minutes of helicopter safety forum.
At this time argued helicopter manufacturer remains that mistake by one of the hangers, specifically attached to the MGB suspension bar, was a likely trigger for the main rotor loosened.
In the minutes it emerged that Norwegian expertise find it difficult to understand that too much torque on fixing bolts to support braces on MGB should be able to cause a break in the support structure.
- This position Airbus Helicopters had taken, was solely founded on proprietary research. We are critical of the factory as much has been leaning in one direction instead of being more open in an early exploration phase, says SF leader Anders Røsok to TU.
TU has asked Airbus Helicopters question whether they still believe that the primary cause of Turøy accident is outside the MGB.
A spokesman for the helicopter manufacturer says the TU that the only thing they will be quoted on now, is that they work closely with the Norwegian Accident Investigation Board and that they do not rule out some causes.
In conversation also shows that Airbus did not entirely agree with SF-abstract. Their version is that the message on May 20 was that it was too early to draw parallels to the 2009 accident, not to categorically reject any similarities.
TU mentioned last week that the reconditioned main gearbox, which was installed in the accident helicopter on January 17, was subjected to "rough treatment" and had to return to the workshop before installation.
This is among several things AIBN now look more closely at, and which also was the topic of helicopter forum, shows the minutes.
- SF wanted to know what was done by transport damage in Australia. AH explained the process when this transmission came into the AH for repair. They were further asked whether it was possible to see the strip down the report by the overhaul of the MGB. AH would check up.
The highlights are mine.
Note that the box was overhauled/repaired by AH, if the text is correct.
Last edited by Apate; 10th Jun 2016 at 08:48.