R22 & R44 blade delamination
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Originally Posted by topendtorque
it appears that investigation has revealed that the blade had been being over zealously polished with a power drill attachment, thus heating the skin edges too much for the glue integrity.
Again, no offense, and I am not trying to protect RHC, generalspecific or HKAC. I just heard that story from another source (Pilots Safety Course) in another version.
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Thanks, found it. Any idea on that accident with the power line inspection, that was apparently caused by using power tools on the blades?
All this attention that the RHC blades get is starting to worry me.
All this attention that the RHC blades get is starting to worry me.
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nope no one has been doing any funky polishing of the blades. I should clarify.. Engineer found evidence of debonding on the tap test sent it back to Robinson and they said new blade time.
Out of interest TOT why is my comment on the heat and the proximity to the sea rubbish?
My reference was in respect of the NTSB's suggestion that this was a set of conditions that was likely to lead to more early life blade failures and the fact that we are ..um.. near the sea and in 40 degree heat
Out of interest TOT why is my comment on the heat and the proximity to the sea rubbish?
My reference was in respect of the NTSB's suggestion that this was a set of conditions that was likely to lead to more early life blade failures and the fact that we are ..um.. near the sea and in 40 degree heat
This is all getting a bit cross-wired.
Yes - RHC have constantly told people not to use power tools for prepping blade surfaces. In any case, any qualified engineer would understand that the immense local heat caused by a power tool on any surface can cause heat damage. Let alone the effect on bonding.
Generalspecific's problem might be related to location. How often does the helicopter get left in extremely strong sunlight with no cooling breezes ? The surface temp of black metal can rocket in those circumstances, causing heat sink back into adjoined components and materials.
I would suggest that a full disclosure of the circumstances to both your RHC distributor and RHC would get their attention. Blades are covered by warranty - so there must be a reason why they feel yours don't get that cover.
Yes - RHC have constantly told people not to use power tools for prepping blade surfaces. In any case, any qualified engineer would understand that the immense local heat caused by a power tool on any surface can cause heat damage. Let alone the effect on bonding.
Generalspecific's problem might be related to location. How often does the helicopter get left in extremely strong sunlight with no cooling breezes ? The surface temp of black metal can rocket in those circumstances, causing heat sink back into adjoined components and materials.
I would suggest that a full disclosure of the circumstances to both your RHC distributor and RHC would get their attention. Blades are covered by warranty - so there must be a reason why they feel yours don't get that cover.
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Out of interest TOT why is my comment on the heat and the proximity to the sea rubbish?
My reference was in respect of the NTSB's suggestion that this was a set of conditions that was likely to lead to more early life blade failures and the fact that we are ..um.. near the sea and in 40 degree heat
My reference was in respect of the NTSB's suggestion that this was a set of conditions that was likely to lead to more early life blade failures and the fact that we are ..um.. near the sea and in 40 degree heat
I am sure that what you are saying is quite true, but if a factory agent said that is why you have a problem with debonding then I say, he is talking rubbish.
If NTSB is saying that then it confirms what many of us already know. That is that many of their operatives would be out of place in a wheelbarrow repair station, let alone a modern helicopter's textbook.
Regularly helicopters in this neck of the woods during November sit in the bright sunshine all day at up to 50 degrees C free air temp, crank up and fly away with no problems.
If NTSB think that Robinson didn't take those temps into consideration when they were designing blades then they're not on this planet. Plenty of places in America where R44's might be operating where those temps would look like a walk in the park i guess.
I would think that there was a factory problem if you are operating at a cool forty degrees and the blades are debonding and there are no extraneous circumstances.
Salt air? forget about that, the blades are supposed to be sealed up with paint are they not, heavy gravelly dust or sand would be extremely more abrasive than a bit of salt. I guess with your ownership structure that the blades were regularly washed anyway.
I deliberately threw a line about the power tool to see if you may have had a underlying problem that you needed to take care of. No harm meant.
There have been some (R44 blades I mean) not far from here that were returned, I don't know how many were replaced FOC, however they first indicated the problem with an out of track problem that could not be rectified. I believe tha the tap tests were a bit inconclusive on some.
As Jim Ball says cover you claim with a stat dec if necessary, and certainly a defect report correctly set out and all signed up before they are packed off to the factory. Make sure that you separate the engineer who does the defect from the engineer who may represent Robinson.
A bit like selling cattle, work out first who is working for you the vendor and not the buyer.
all the best
tet
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I think that R44 MM reference I noted specifically mentions a temperature limit of 175 degrees Farenheit, but it was 10 hrs ago I read it so it kind of went into semi auto-dump in my mind........
TeT - it is the combination of high temperatures and high humidity that damages composite materials and their bonding agents. The comment about hot and wet is valid.
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it is the combination of high temperatures and high humidity that damages composite materials and their bonding agents. The comment about hot and wet is valid.
But, you tell me how the "wet" is supposed to get into where the "bonding agents" live short of faulty workmanship and I will then start agreeing with the wheelbarrow technician that Robinson blades aren't fit for the tropics.
I did have an idea that they are certified for all over the world operations.
ding ding, ding ding.
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Any ideas what the melting point is for the bonding material on the blades? It seems ludicrous that it would be low enough to be reached in the sunlight on a hot day. That would be a case of very bad design...
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Gypsy, its called "built in continuous profit maker for Uncle Frank" because of the power situation the blades need to be as light as a feather, but in doing this the inards are made of kitchen foil to resemble the home of a Bee, then they put some thicker kitchen foil over the top and stick it down with some strong glue stuff, when it gets hot and/or wet as well thats when chemistry starts to work on it and heyfranko there ya go again another customer damaged blade, ... that'll be £20k thank you.
solution heavy gauge Blades, so that needs more power from the mil, that needs stronger gearbox and bigger elastic bands, that needs a stronger airframe, that needs bigger petrol tank, that needs a bigger wallet !!
where do you stop this sort of problem, ... best go for a different make... but take your bigger wallet!
VfrpilotPb
Peter R-B
solution heavy gauge Blades, so that needs more power from the mil, that needs stronger gearbox and bigger elastic bands, that needs a stronger airframe, that needs bigger petrol tank, that needs a bigger wallet !!
where do you stop this sort of problem, ... best go for a different make... but take your bigger wallet!
VfrpilotPb
Peter R-B
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That's either cynical or a scary thought... I know fridges have built-in expiry, but I don't like the idea of it when I'm 800 feet up in the air!
They've probably done about the best they can within the weight limits. That's the whole point and beauty of the Robbies.
They've probably done about the best they can within the weight limits. That's the whole point and beauty of the Robbies.
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I guess the cynical bit we'll all work out when we see a tube of vaseline supplied with the brand new helicopter.
Mind you, thinking of profit margins????
For Instance, none of the thousands of international customers have as yet seen from the grand gentleman - as part of their new machine kit - a US one quarter, or a definition of such to help them with their internationally approved Maintenance Manual which describes the mandatory tap test in detail.
Every other damm thing has to have a release note and a definition. - fuel - bolts - seat belts - etc.
Perhaps, we , yes, perhaps we will just have to supply our own lard.
I have heard that indeed there are to be new blades, which will descend to the other types from the goat stable, and surprise surprise, they will have the same alloy skins as from before the advent of the stainless steel blades
Mind you, thinking of profit margins????
For Instance, none of the thousands of international customers have as yet seen from the grand gentleman - as part of their new machine kit - a US one quarter, or a definition of such to help them with their internationally approved Maintenance Manual which describes the mandatory tap test in detail.
Every other damm thing has to have a release note and a definition. - fuel - bolts - seat belts - etc.
Perhaps, we , yes, perhaps we will just have to supply our own lard.
I have heard that indeed there are to be new blades, which will descend to the other types from the goat stable, and surprise surprise, they will have the same alloy skins as from before the advent of the stainless steel blades
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6/2008 NTSB safety recommendation, main rotor blades
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Originally Posted by topendtorque
For Instance, none of the thousands of international customers have as yet seen from the grand gentleman - as part of their new machine kit - a US one quarter, or a definition of such to help them with their internationally approved Maintenance Manual which describes the mandatory tap test in detail.
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thanks rotormatic for bringing that report to our attention.
very sobering, printed off after two reads .......??
all i can say at this stage is that the paint industry looks like doing well.
very sobering, printed off after two reads .......??
all i can say at this stage is that the paint industry looks like doing well.
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Washing
I am led to believe that the idea of the bond is to stick the two surfaces together and also to seal it. The paint also seals the surface and bond line.
So why is it so important to wash the blades prior to storage?
I can understand a chemical reaction (salt/sand/etc) leading to a degredation of the actual metal surface, but how does that lead to de-bonding?
So why is it so important to wash the blades prior to storage?
I can understand a chemical reaction (salt/sand/etc) leading to a degredation of the actual metal surface, but how does that lead to de-bonding?
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You're onto it CY, there is a major problem with the underlying logic of the paper.
It seems to me that what they are trying to say is that there could be a breakdown in the integrity of the bonding within the blade structure, which causes a crack to appear on the outside, from the inside out.
Therefore there is need to establish an NDI test to detect the breakdown before either there is a crack visible or more seriously, a void occurs during flight which leads to cracking and catastrophic failure.
That I have no problem with, other than operating the product. although I must say the eyes get a bit tired checking the whizzing blade for cracks every time it goes by.
However, There is also a sweeping statement about "warm moist" environments, as if to indicate that is which causes a breakdown of the blade structure. As you suggest how can this happen through a sealed surface?
More particularly how can a moist environment lead to cracking which might happen with a structure that has become more brittle, due to say, drying?
Indeed what is the moisture content of the sealed bonding inside the product (blade) as it leaves the factory and as the hours tick down? Has there been a scientific measurement of that?
Now to digress, I think we all recognise that Al Gore is laughing all the way to the bank with his sweeping statements about climate change, but he and this "warm moist" statement have something in common.
It is that sweeping statements such as that should always be substantiated with scientific examination that had well documented replication and peer review, and they should never be made without them.
I look forward to a new ultra sound test procedure, the rest I think we can discard as rubbish. I have no problems with the suggested 10x visual inspections, although I've noticed that most junior pilots these days don't even know what a ten power is.
I worked out that the US quarter, is very similar is size and weight to our ten cent piece. Under the circumstances i'm not really into some tired joke about that worthless weight, especially after flying two of these blades all day.
tet
It seems to me that what they are trying to say is that there could be a breakdown in the integrity of the bonding within the blade structure, which causes a crack to appear on the outside, from the inside out.
Therefore there is need to establish an NDI test to detect the breakdown before either there is a crack visible or more seriously, a void occurs during flight which leads to cracking and catastrophic failure.
That I have no problem with, other than operating the product. although I must say the eyes get a bit tired checking the whizzing blade for cracks every time it goes by.
However, There is also a sweeping statement about "warm moist" environments, as if to indicate that is which causes a breakdown of the blade structure. As you suggest how can this happen through a sealed surface?
More particularly how can a moist environment lead to cracking which might happen with a structure that has become more brittle, due to say, drying?
Indeed what is the moisture content of the sealed bonding inside the product (blade) as it leaves the factory and as the hours tick down? Has there been a scientific measurement of that?
Now to digress, I think we all recognise that Al Gore is laughing all the way to the bank with his sweeping statements about climate change, but he and this "warm moist" statement have something in common.
It is that sweeping statements such as that should always be substantiated with scientific examination that had well documented replication and peer review, and they should never be made without them.
I look forward to a new ultra sound test procedure, the rest I think we can discard as rubbish. I have no problems with the suggested 10x visual inspections, although I've noticed that most junior pilots these days don't even know what a ten power is.
I worked out that the US quarter, is very similar is size and weight to our ten cent piece. Under the circumstances i'm not really into some tired joke about that worthless weight, especially after flying two of these blades all day.
tet
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I'm a bit surprised that all of our operators, technocrats and voyeurs of robinson blades have let this NTSB bulletin go through to the keeper without even a decibel.
why, not even Nigelh has submitted a yawn!
why, not even Nigelh has submitted a yawn!
after reading the report it makes me wish i were somewhere else in another type of machine. it does worry me however that perhaps the failure is started internally then the first failure on a blade with the new tape will be blamed on the tape and the problem remain unresolved. speculation i know but i am unconvinced that the paint maketh the machine..
and if it does then we are in trouble as were yet to find a paint that lasts 200 hrs!!
and if it does then we are in trouble as were yet to find a paint that lasts 200 hrs!!