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CH-148 Cyclone Progress

KevinB

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While nothing specific about the RCAF Cyclone - I found it interest that Sikorsky was flying a two tone grey 92 around my house this afternoon in some very odd and erratic hard turning maneuvers - I snapped some pictures from my iPhone while hanging Christmas lights, but the overcast sky didn't do much with me on a ladder so I doubt anyone cares for a pixelated blob.
 

AM Sup

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SIK has been pretty consistent in stating that this particular issue on the 148 is not something they've seen on the S92. No definitive root cause that they've released to us yet.
 

TCM621

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From what I have been told, the cracks are in the tail section near where the tail and the fuselage join. They are structural in nature. I have also been told that Sikorsky had known about the issue with the 92Fs but hadn't informed the military, although this could just be rumour so we should wait for verification on that particular front.
 

AM Sup

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From what I have been told, the cracks are in the tail section near where the tail and the fuselage join. They are structural in nature. I have also been told that Sikorsky had known about the issue with the 92Fs but hadn't informed the military, although this could just be rumour so we should wait for verification on that particular front.
We've asked about the 92 cracking during conversations with SIK engineering and they've told us that our issue is not related to that. It's sometimes a 'good' thing when we can find commonality between our frames and the S92. It can give us a much larger bank of flight hours to draw upon when trying to establish frequency or severity of occurrence. It wasn't an option here.
 

AM Sup

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After spending some time in meetings with some pretty smart folks on the SIK side and on our side, they have some theories but nothing settled. I understand that they might be able to ID the root cause by getting the cracked portions cut out and sent for analysis. How they do that... I've only a basic idea. I'm sure there's someone in this group who can speak to how they might classify stress or fatigue from a sample.
 

suffolkowner

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After spending some time in meetings with some pretty smart folks on the SIK side and on our side, they have some theories but nothing settled. I understand that they might be able to ID the root cause by getting the cracked portions cut out and sent for analysis. How they do that... I've only a basic idea. I'm sure there's someone in this group who can speak to how they might classify stress or fatigue from a sample.
Magnaflux?
 

KevinB

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Magnaflux?
Works for detecting cracks - but not much analysis beyond that.

I suspect they will take samples from the areas of issue.

Confirming material composition using a combination of Energy Dispersive X-Ray Spectroscopy (EDS),
X-ray Photoelectron Spectrometer (XPS), and verification with X-Ray Florescence Spectrometer (XRF).

I suspect that certified material was used - however when conducting any analysis you will need to confirm the materials first.
You will get a number of relative weight charts and EDS micrographs of the various samples, binding energy graphs from XPS - this will also confirm that the materials are within spec - and if you have some without cracking if the materials are slightly different in ones with failure and without.
As well you need to examine the substrate and surface and determine what has occurred from heat treatment (e.g., quench and tempering, induction hardening, flame hardening, laser hardening, and electron beam hardening), thermochemical treatment (e.g., carburizing, carbonitriding, nitriding, nitrocarburising, and boriding) or implantation (e.g., of nitrogen ions). Treatments are commonly used to improve properties such as hardness.

Without writing a paper on metallurgical analysis (which I am wholly unqualified to do) it's hard to explain everything that needs to get done - and we haven't even started to get in to what is done to examine metal treatment or coatings...

Then once all of that is done - one needs to compare it to the model and how the model compares in Stress Analysis software to what is being observed -- the problem with ANSYS type software is garbage in --> worse garbage out - so if the stresses on parts wasn't correctly anticipated - the models won't show you a valid representation of what occurs - and you end up with catastrophic issues - or parts severely over engineered.
 

Good2Golf

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…and ultrasonic and Eddy current in addition to X-ray, for aluminum. I’m not even sure Magnaflux works on aluminum? I only saw it used on ferrous or semi-ferrous metals.
 

RaceAddict

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According to the CBC article:

Sikorsky is working with the RCAF to make repairs, according to the department. RCAF experts estimate that the repairs to some of the aircraft will be completed in "the next few days."

So, whatever the issue is, it's a relatively simple fix. Something they can do in "the next few days" isn't reengineering anything... they're just replacing a cracked part with a non-cracked part. Will the fix be permanent? Or will the new parts just have to be subsequently inspected at much lower intervals?
 

Colin Parkinson

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Likely it's a direct replacement with the same part, followed by a whole bunch of engineering to create a better part that does not create problems with other existing parts around it.
 

KevinB

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According to the CBC article:



So, whatever the issue is, it's a relatively simple fix. Something they can do in "the next few days" isn't reengineering anything... they're just replacing a cracked part with a non-cracked part. Will the fix be permanent? Or will the new parts just have to be subsequently inspected at much lower intervals?


Likely it's a direct replacement with the same part, followed by a whole bunch of engineering to create a better part that does not create problems with other existing parts around it.
Yup.

Sounds like a simple replacement of swappable parts.
So it isn't a fix, it's just a make shift solution until they can analyze the parts and figure out what a long term solution will be.
…and ultrasonic and Eddy current in addition to X-ray, for aluminum. I’m not even sure Magnaflux works on aluminum? I only saw it used on ferrous or semi-ferrous metals.
It needs to be magnetized - so Magna-flux won't work for Aluminum - but I'm sure there are some other alloys involved in the tail structure as well.

I couldn't see any images as to exactly what cracked - I would guess it to be aft of the hinge on the tail boom, or portions of the hinge (which I strongly doubt would be aluminum for that role).
 

OceanBonfire

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So one has been repaired:



"The location of the cracks on the tail structure are unique for each aircraft, although they are on the aircraft's frame and no cracking was found on the tail hinge or its components," the air force said in a news release on Wednesday.


 

OceanBonfire

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Not until spring we'd know how much it cost and how extensive the fix is for the software issue:


 

OceanBonfire

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The tail repairs are considered "non-standard":


 

AM Sup

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Non-standard repairs are quite common. It basically means that the issue is either something for which we have no approved repair scheme or it's something for which we have a repair scheme but the unserviceability exceeds published repair/damage limits in the maintenance manual. There are a lot of them on the 148 and they range from minor touch-ups for scratches in protective coatings all the way up to what we've got with this tail issue.
 

SeaKingTacco

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Non-standard repairs are quite common. It basically means that the issue is either something for which we have no approved repair scheme or it's something for which we have a repair scheme but the unserviceability exceeds published repair/damage limits in the maintenance manual. There are a lot of them on the 148 and they range from minor touch-ups for scratches in protective coatings all the way up to what we've got with this tail issue.
Thumbs up to what AM Sup said.

”Non-Standard” has specific meaning in aviation industry. It does not mean “sub-standard”. A better way of looking at it is that each repair is bespoke or individualized to a particular tail number.
 

TCM621

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Thumbs up to what AM Sup said.

”Non-Standard” has specific meaning in aviation industry. It does not mean “sub-standard”. A better way of looking at it is that each repair is bespoke or individualized to a particular tail number.
I don't think we can afford bespoke repairs.
 

SeaKingTacco

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I don't think we can afford bespoke repairs.
What exactly is your experience with aviation?

Every single aircraft that is flying today in the world, civil or military, probably has at least one NSR in it’s maintenance history. It is a perfect normal procedure.

But, you know, internet experts are going to ”expert”…
 
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