Yet another AW139 tail incident at Gulf helis
Joined: Dec 2000
Aviation Qualifications: Non-Aircrew
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From: Arlington, Tx. US
tcv
You left out the UH-60 and the S-76 shucking main rotor blades due to spindle failure. There was also the Govt of Kentucky S-76 that shucked a tail rotor blade. The report was that the tail rotor blade was used in ultimate load tests and instead of being scrapped as is practiced was repainted and delivered.
The Sultan
You left out the UH-60 and the S-76 shucking main rotor blades due to spindle failure. There was also the Govt of Kentucky S-76 that shucked a tail rotor blade. The report was that the tail rotor blade was used in ultimate load tests and instead of being scrapped as is practiced was repainted and delivered.
The Sultan
Joined: Jul 2007
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From: Global
The Kentucky accident was due to a unsecured engine cowling which resulted in the loss of one TR blade, but the gearbox did not separate from the airframe, it also contacted the MR and the TR driveshaft. NTSB report NYC92GA147.
Joined: Apr 2000
Aviation Qualifications: ATP+Mil
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From: EGDC
Well they must have found a faulty blade at Lee on Solent yesterday - their 139 was off state for a 'tail rotor crack' and the Portland one stood in overnight.
TCV - the big difference here is that with conventional engineering, more sensitive NDT procedures can be used to identify cracks before they become visible. With the composite blade roots you can only use the 'technologically advanced' tap test which may or may not identify voids (which really shouldn't exist at all in such important structures) and rely on visual inspection to see any surface cracks.
I agree the 139 will become an outstanding and safe aircraft but only if AW address their composite material manufacturing process and quality assurance testing as per Blackmax's suggestions.
TCV - the big difference here is that with conventional engineering, more sensitive NDT procedures can be used to identify cracks before they become visible. With the composite blade roots you can only use the 'technologically advanced' tap test which may or may not identify voids (which really shouldn't exist at all in such important structures) and rely on visual inspection to see any surface cracks.
I agree the 139 will become an outstanding and safe aircraft but only if AW address their composite material manufacturing process and quality assurance testing as per Blackmax's suggestions.
Chief Bottle Washer
Joined: Sep 2000
Aviation Qualifications: ATPL
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From: PPRuNe
Originally Posted by [email protected]
I agree the 139 will become an outstanding and safe aircraft but only if AW address their composite material manufacturing process and quality assurance testing as per Blackmax's suggestions.
Or has there been a recent change in quality control at AW that has resulted in what seems to be a rash of composite bond problems?
Joined: Jan 2005
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From: Out there somewhere
After all the S92 negative traffic, it looks like this helo has joined the POS brigade also.
Joined: Mar 2008
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From: Doha, Qatar
^
I work offshore in Qatar and fly on Gulf Helicopters aircraft offshore on a regular basis. I have never had a bad flight on the AW139 out here. Comfort wise its a good tool for operations offshore.
My concern is that these TR AND TRB issues need to be resolved. Whether it is a manufacturing AW issue, a Fleet issue GH, or a poor maintenace issue GH, someone needs to put their hands up and say its our problem.
Looking at the bulletin that has come out from AW it seems that there are issues concerning manufacturing and warnings for increased inspections and service intervals. If this is AW holding their hands up and saying this is our problem its a very poor way of admitting their production process is not up to the standard required.
There needs to be a better way of testing a rotor blade than tapping it with a special hammer.
I am not convinced by AW in this at all.
I work offshore in Qatar and fly on Gulf Helicopters aircraft offshore on a regular basis. I have never had a bad flight on the AW139 out here. Comfort wise its a good tool for operations offshore.
My concern is that these TR AND TRB issues need to be resolved. Whether it is a manufacturing AW issue, a Fleet issue GH, or a poor maintenace issue GH, someone needs to put their hands up and say its our problem.
Looking at the bulletin that has come out from AW it seems that there are issues concerning manufacturing and warnings for increased inspections and service intervals. If this is AW holding their hands up and saying this is our problem its a very poor way of admitting their production process is not up to the standard required.
There needs to be a better way of testing a rotor blade than tapping it with a special hammer.
I am not convinced by AW in this at all.
Joined: Jan 2009
Posts: 821
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From: no comment ;)
Out there on field it is sad true, no standard certified NDT procedure
other than "modern" tap test
So it is time to use ultrasound, like this one:
(I am not related with producer
)
http://www.olympus-ims.com/en/.downl...998&lang=en_US
http://www.olympus-ims.com/en/.downl...996&lang=en_US
Who is going to make "certification"?
Or visit your doctor and take some ultrasound souvenirs from there
other than "modern" tap test
So it is time to use ultrasound, like this one:
(I am not related with producer
)http://www.olympus-ims.com/en/.downl...998&lang=en_US
http://www.olympus-ims.com/en/.downl...996&lang=en_US
Who is going to make "certification"?
Or visit your doctor and take some ultrasound souvenirs from there
Joined: Jun 2006
Posts: 1,022
Likes: 2
From: In the air with luck
9A
Interesting tools could\should show the tail section disbonds, when they have reached a level that is measurable.
How quick is the de lamination\ failure once it starts ?
So far the tails have been on ground, & the HK is suspected blade failure, it would appear that there are numerous others reported here (that cannot be all not every user is a PPRUNER)
If as BM is saying these could be due to micro bubbles, the way I read the literature, it does not go down to the level that is starting these problems.
It would appear that manufacturers are using either flawed calculations, poor \ incorrect procedures, or the material is not stable enough for the job.
Interesting tools could\should show the tail section disbonds, when they have reached a level that is measurable.
How quick is the de lamination\ failure once it starts ?
So far the tails have been on ground, & the HK is suspected blade failure, it would appear that there are numerous others reported here (that cannot be all not every user is a PPRUNER)
If as BM is saying these could be due to micro bubbles, the way I read the literature, it does not go down to the level that is starting these problems.
It would appear that manufacturers are using either flawed calculations, poor \ incorrect procedures, or the material is not stable enough for the job.
Joined: Jul 2008
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From: Australia
500e
The size of these bubbles is small, and individually they are much smaller than the tolerable defect size determined during certification testing. However, collectively the sum total of the voids can well and truly exceed the TDS. In the case of extensive micro-voiding the adhesive surrounding any disbond may have a shear strength of only 50% of the prisitine adhesive bond. Further, the reduced strength may result in fatigue of the small segments of adhesive between the bubbles, leading to disbonding. A further complication is that when an OEM undertakes certification tests they use a teflon insert in an otherwise pristine bond, where the inserted "dsibond" is surrounded by good adhesive. The same approach is used for damage tolerance analysis using computer modelling, where the properties of the adjacent adhesive are unaltered for the purposes of modelling. Most of the literature considers only on this type of large voids (macro-voids).
Hence the certification basis for the original damage tolerance analysis and the computer modelling are compromised if the adhesive has extensive micro-voids.
I am preparing a paper for a conference in Brisbane in July on this and other risks to safety as a result of the application of damage tolerance analysis to adhesive bonds. I'll post it on my web site after the conference.
Regards
blakmax
If as BM is saying these could be due to micro bubbles, the way I read the literature, it does not go down to the level that is starting these problems.
Hence the certification basis for the original damage tolerance analysis and the computer modelling are compromised if the adhesive has extensive micro-voids.
I am preparing a paper for a conference in Brisbane in July on this and other risks to safety as a result of the application of damage tolerance analysis to adhesive bonds. I'll post it on my web site after the conference.
Regards
blakmax
Joined: Jul 2008
Posts: 372
Likes: 0
From: Australia
Conference link
Alan
Hopefully this link works Aircraft Airworthiness and Sustainment Conferences
I believe that my paper is scheduled for Wednesday. I can only attend the conference for that day, so make yourself known to me if you wish.
Regards
Max
Hopefully this link works Aircraft Airworthiness and Sustainment Conferences
I believe that my paper is scheduled for Wednesday. I can only attend the conference for that day, so make yourself known to me if you wish.
Regards
Max
Joined: Nov 2003
Posts: 1,079
Likes: 5
From: Abu Dhabi
Originally Posted by [email protected]
Well they must have found a faulty blade at Lee on Solent yesterday - their 139 was off state for a 'tail rotor crack' and the Portland one stood in overnight.
Turkeyslapper
My operator here in the ME has grounded aircraft pending tail rotor inspections of the area of interest....one u/s blade with crack so far and waiting.
My operator here in the ME has grounded aircraft pending tail rotor inspections of the area of interest....one u/s blade with crack so far and waiting.
Thanks
Aser
Joined: May 2005
Posts: 369
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From: Europe trying to enjoy retirement “YES”
Just drifting back a while, I seem to recall a tail rotor blade *inspection called by Augusta regarding the same area as this one re cracking.
I also remember a number of tail rotor blades that showed cracking in the paint covering. Removing the paint layer showed progression through the first layer or two of the carbon fibre Multy layers. These blades returned for repair.*
Question was the blade in question one of these? Is this latest failure a progression of the original problem? how many hours on the subject blade? What was learned by Augusta from the results of the original problem that generated the original inspection.
I also remember a number of tail rotor blades that showed cracking in the paint covering. Removing the paint layer showed progression through the first layer or two of the carbon fibre Multy layers. These blades returned for repair.*
Question was the blade in question one of these? Is this latest failure a progression of the original problem? how many hours on the subject blade? What was learned by Augusta from the results of the original problem that generated the original inspection.