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EC225 crash near Bergen, Norway April 2016

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EC225 crash near Bergen, Norway April 2016

Old 9th Jun 2016, 00:54
  #1241 (permalink)  
 
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Originally Posted by HeliComparator View Post
This was said to be an engine gov warning light -according to rumour anyway.
GOV light is a common defect on this Aircraft and is almost always an Electronic Bleed Valve.
I am willing to bet the Component change was a Bleed Valve

Last edited by buzz66; 9th Jun 2016 at 01:14.
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Old 9th Jun 2016, 02:11
  #1242 (permalink)  
 
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HC,


...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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Old 9th Jun 2016, 04:10
  #1243 (permalink)  
 
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from HC:
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
Also: Status of front suspension bar (missing or not), status of front attachment area - pins missing?, holding pin?, front bracket damage?

.....crickets.
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Old 9th Jun 2016, 05:08
  #1244 (permalink)  
 
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Originally Posted by Colibri49 View Post
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?
Lube oil magnetic chip detectors with fuzz suppression circuitry have been standard practice with aircraft engines/gearboxes for many years. The chip detector has magnetic sensor rings with a short gap between them. When enough ferrous metal debris accumulates to bridge the gap it closes a circuit that signals a potential fault. Some systems automatically perform one or two burn-off cycles prior to sending a warning signal.

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.
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Old 9th Jun 2016, 08:05
  #1245 (permalink)  
 
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Originally Posted by buzz66 View Post
Fire Detectors use an Integrity Resistor to prevent False Fire Warnings. Chip detectors do NOT have any Integrity resistors.
Test resistors are used on Fire Bottle, Winch Cut, ETC type Squibs to limit the current during integrity test.
I don't think you can be right about the resistors. If no resistors, what does the chip detector test function do?

Perhaps you are thinking about resistors in series? I am thinking about a resistor in parallel within the body of the detector.
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Old 9th Jun 2016, 08:14
  #1246 (permalink)  
 
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The chip detector has magnetic sensor rings with a short gap between them.
Which is all fine until the detector loses some of it's magnetism.

Some maintenance procedures call up regular checking with a "test piece".

A surprising number of maintenance manuals don't.

Just saying.
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Old 9th Jun 2016, 18:07
  #1247 (permalink)  
CTR
 
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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.
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Old 9th Jun 2016, 20:51
  #1248 (permalink)  
 
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Originally Posted by CTR View Post
"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.
Eggzacary.

(Or on the ground, either)
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Old 9th Jun 2016, 20:54
  #1249 (permalink)  
 
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Originally Posted by SASless View Post
HC,
Conspiracy Theory a Hobby of yours now days since you have retired?
Possibly. But he is spot on insofar as we are still lacking the most basic and easy to obtain information. The silence is deafening...
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Old 9th Jun 2016, 21:09
  #1250 (permalink)  
 
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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.
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Old 9th Jun 2016, 21:40
  #1251 (permalink)  
 
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Originally Posted by SASless View Post
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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Old 9th Jun 2016, 21:54
  #1252 (permalink)  
 
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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.
How do you know what information has been withheld, if it's been withheld?
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Old 9th Jun 2016, 22:09
  #1253 (permalink)  
 
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Originally Posted by Satcomm View Post
How do you know what information has been withheld, if it's been withheld?
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?
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Old 9th Jun 2016, 22:33
  #1254 (permalink)  
 
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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.
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Old 9th Jun 2016, 23:38
  #1255 (permalink)  
 
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Diversification,

When you look at the cross section drawing of the transmission
cross section
you can see these are spherical roller bearings

SLB
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Old 10th Jun 2016, 03:28
  #1256 (permalink)  
 
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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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Old 10th Jun 2016, 08:05
  #1257 (permalink)  
 
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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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Old 10th Jun 2016, 08:41
  #1258 (permalink)  
 
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Originally Posted by HeliComparator View Post
This is true. However it is interesting to note what information has been leaked / drip fed, and what info has been withheld.
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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Old 10th Jun 2016, 08:49
  #1259 (permalink)  
 
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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?
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Old 10th Jun 2016, 09:32
  #1260 (permalink)  
 
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Originally Posted by HeliComparator View Post
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?
I fully agree with HeliComparator!

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.
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