R22 & R44 blade delamination
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Robbie blade delamination
I'm going to have to call Bullsh*t.
Now that we have definitive proof that these blades are delaminating and the delamination can't be blamed on an accident rather than being the cause it seems that Robinson is going to have a crack at the operator for not keeping blades painted. So let me get this straight, the blades are held together by the paint? Makes you want to go out and become a robbie owner doesn't it? What if I'm 200 miles from home and its raining? Do I land every five minutes to check that the paint holding my $400,000 aircraft together is still there. We keep hearing about all the broken helicopter sales records. What happens to all those $$$$$s, obviously not enough being spent on R & D. Get real Frank, enough excuses, don't make another bloody helicopter before you get the first ones right.
I can stuff up my duty times by .5 and get hammered by CASA yet they don't want to know about helis flying apart in flight????????????????????????????????
Now that we have definitive proof that these blades are delaminating and the delamination can't be blamed on an accident rather than being the cause it seems that Robinson is going to have a crack at the operator for not keeping blades painted. So let me get this straight, the blades are held together by the paint? Makes you want to go out and become a robbie owner doesn't it? What if I'm 200 miles from home and its raining? Do I land every five minutes to check that the paint holding my $400,000 aircraft together is still there. We keep hearing about all the broken helicopter sales records. What happens to all those $$$$$s, obviously not enough being spent on R & D. Get real Frank, enough excuses, don't make another bloody helicopter before you get the first ones right.
I can stuff up my duty times by .5 and get hammered by CASA yet they don't want to know about helis flying apart in flight????????????????????????????????
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ericferrit
if you have access to the link provided by 'bellytank' you'll also be able to access the other SL mentioned from the RHC site. There does not appear to be much variation in those notes from the MM. Merely tap test the bonded areas of the skin and do the old ten power trick up and down the bond lines.
Helicopspeeder
we sure as hell share your frustations and the more heat the better I feel.
With regard to "John eacott's" notes I would say that there is ample evidence that the honeycomb was short by a substantial amount on the leading edge row.
This must have meant that the skin was allowed to flex ad-infinitum at that point thus setting up a fatigue cracking action upon the bonded section. I don't think it would have mattered whether it was properly bonded onto the spar or not.
The lack of honeycomb support meant that the bond was going to come away sooner or later. There was plenty of time for the later bit as the blade has 1600 hours remaining!
Maybe the repainting will push the pressure and vibratory characteristics of the prevailing relative wind further forward, until it wears down yet again.
If, that retards the cracking action and protects the skin, then it is a good investment. but to be relying on such a flimsy safegard is as you say a moumental indictment of sloppy engineering and safety principles.
1) the quality control should have ensured that the honeycomb was ALL the way to the leading edge, a very simple task one might say, and
2) the stainless steel is gong to have to be treated so that it will bond 100% of the intended areas, no less.
Grounding, or attempting to ground the A/C is sure as hell gonna kick up a stink.
if you have access to the link provided by 'bellytank' you'll also be able to access the other SL mentioned from the RHC site. There does not appear to be much variation in those notes from the MM. Merely tap test the bonded areas of the skin and do the old ten power trick up and down the bond lines.
Helicopspeeder
we sure as hell share your frustations and the more heat the better I feel.
With regard to "John eacott's" notes I would say that there is ample evidence that the honeycomb was short by a substantial amount on the leading edge row.
This must have meant that the skin was allowed to flex ad-infinitum at that point thus setting up a fatigue cracking action upon the bonded section. I don't think it would have mattered whether it was properly bonded onto the spar or not.
The lack of honeycomb support meant that the bond was going to come away sooner or later. There was plenty of time for the later bit as the blade has 1600 hours remaining!
Maybe the repainting will push the pressure and vibratory characteristics of the prevailing relative wind further forward, until it wears down yet again.
If, that retards the cracking action and protects the skin, then it is a good investment. but to be relying on such a flimsy safegard is as you say a moumental indictment of sloppy engineering and safety principles.
1) the quality control should have ensured that the honeycomb was ALL the way to the leading edge, a very simple task one might say, and
2) the stainless steel is gong to have to be treated so that it will bond 100% of the intended areas, no less.
Grounding, or attempting to ground the A/C is sure as hell gonna kick up a stink.
Thanks for the info on the tap test and visual inspection.
I was mentally comparing the problem to the issue involving debonding of MD 500 tail rotor blade leading edge strips. It was found that the tap test did not give sufficient warning of a debond. Hence the requirement to use dye pen around the skin/strip bond line. Any minor debond would hold the dye and it would show under developer.
It works as I found out to some embarrasment when I failed to do it properly and another engineer found the debond using this technique.
My point is that a "tap test" is in my opinion inadequate as it relies on hearing
and accuracy of the tapping, in other words operator skill. Given that unlike the 500 edge strips where the bond lines are "out of wind" the skins on the Robinson blades are "into wind" therefore the situation is far more critical.
I believe that the tap test might not show a debond prior to the blade being refinished. It would then continue to debond till it fails.
I was mentally comparing the problem to the issue involving debonding of MD 500 tail rotor blade leading edge strips. It was found that the tap test did not give sufficient warning of a debond. Hence the requirement to use dye pen around the skin/strip bond line. Any minor debond would hold the dye and it would show under developer.
It works as I found out to some embarrasment when I failed to do it properly and another engineer found the debond using this technique.
My point is that a "tap test" is in my opinion inadequate as it relies on hearing
and accuracy of the tapping, in other words operator skill. Given that unlike the 500 edge strips where the bond lines are "out of wind" the skins on the Robinson blades are "into wind" therefore the situation is far more critical.
I believe that the tap test might not show a debond prior to the blade being refinished. It would then continue to debond till it fails.
Last edited by ericferret; 25th Mar 2007 at 14:31. Reason: more info
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Helicopspeeder Wrote: Get real Frank, enough excuses, don't make another bloody helicopter before you get the first ones right.
Yes, I have no doubt that for $100,000 per blade we could have something that could manage differently, but we want to fly at reasonable cost, so we have to live within the parameters that permits. In this case, it means painted blades.
I haven't heard anyone claiming that blades which have retained paint cover are also failing: if they were, we would be in the same position as past recalls and Frank would, I have no doubt, produce a fix, or new blades and there would be a recall, some level of help which would satisfy some people and antagonise others. There would be an interim safety check for us all and if it's very serious the FAA and CAA etc. will ground them.
If you fly a Robinson, you fly the best that can be achieved in a cost effective heli, and that comes with caveats. No, they should never fall out of the sky, but if there are limits to what cost-effective engineering produces, then we, the customers, may have to bear some of the cost burden of sorting it out when things are not perfect, both in time, lost flying hours and money.
If you don't want that kind of flying, don't buy any aircraft built to a budget. You only have to read the Robinson 'return-to-base' warranty to understand its limitations. That's not because Frank doesn't give a sh*t, it's because he has made a helicopter that is affordable to the masses.
I completely understand the concern over resolving the problem, and (as a 22 owner), I'll be checking my blades very carefully. But the way you state that Frank hasn't built the helicopter 'right' suggests that you shouldn't be flying anything which isn't at the pinnacle of engineering excellence regardless of cost. Many of us can't afford that and Robinson represents the best opportunity of safe and cost effective flying in the industry.
If you want to go and spend your life creating a company that builds helicopters 'right' in this market, then go right ahead and if you can do better than Robinson at the same price with less problems, you are going to be a very rich man indeed!
BW
Last edited by bladewashout; 25th Mar 2007 at 19:02.
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ef
The RHC MM specifically warns against using penetrant material anywhere near any bonding line.
I understand how you could miss seeing a witness dye pen indication. I know of another from some time ago where the check was done, because the penetrant showed up in the forensic examination.
I now think it could have been (in that case) that when using the technique in an enclosed area and onto a threaded area that the grooves of the thread could cast a shadow for the spray can application, or if the spray was held too close then all of the surface material may have been washed away.
bladewashout.
I appreciate your post for sure.
However if you imagine that the firmness of the supporting honeycomb could act as a redunancy measure for a not well bonded skin, then how much money will it cost for someone to peruse tha honeycomb before the skin is applied. If the honeycomb was there it would have melted into the bond material at least when it all got cooked.
also how little extra would it cost to just etch the bonded aears of skin? not much i suspect.
The RHC MM specifically warns against using penetrant material anywhere near any bonding line.
I understand how you could miss seeing a witness dye pen indication. I know of another from some time ago where the check was done, because the penetrant showed up in the forensic examination.
I now think it could have been (in that case) that when using the technique in an enclosed area and onto a threaded area that the grooves of the thread could cast a shadow for the spray can application, or if the spray was held too close then all of the surface material may have been washed away.
bladewashout.
I appreciate your post for sure.
However if you imagine that the firmness of the supporting honeycomb could act as a redunancy measure for a not well bonded skin, then how much money will it cost for someone to peruse tha honeycomb before the skin is applied. If the honeycomb was there it would have melted into the bond material at least when it all got cooked.
also how little extra would it cost to just etch the bonded aears of skin? not much i suspect.
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WD40
No chance that these blades have been regularly wiped with WD40 (or similar)?
When this post first came up I think it made mention of the machine being used in coastal Qld for instructing but now I can't find that post. I don't care which school, but it would be interesting to know if they have a policy of getting the students to WD the blades? A light rub on the leading edge is one thing, but a soaking (by an un-supervised/over exhuberant student) would be another.
Cheers FBD
When this post first came up I think it made mention of the machine being used in coastal Qld for instructing but now I can't find that post. I don't care which school, but it would be interesting to know if they have a policy of getting the students to WD the blades? A light rub on the leading edge is one thing, but a soaking (by an un-supervised/over exhuberant student) would be another.Cheers FBD
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Something I'm curious about, since seeing that photo:
It seems like the leading edge metal is underneath the lower skin, so that as the blade rotates, the airflow is 'pushing the lower skin away' from the leading edge. Wouldn't it make more sense to have the leading edge overlap the lower (and presumably upper) skin, so that the integrity of the blade isn't just dependant on the bonding? Or is there a reason this isn't done?
It seems like the leading edge metal is underneath the lower skin, so that as the blade rotates, the airflow is 'pushing the lower skin away' from the leading edge. Wouldn't it make more sense to have the leading edge overlap the lower (and presumably upper) skin, so that the integrity of the blade isn't just dependant on the bonding? Or is there a reason this isn't done?
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R22 Delamination
Hey Bladewashout,
Great post, well put and some very good points. My anger comes for a number of reasons. Chiefly the excuses that have been used and the blame game reulting from previous accidents which we all are pretty confident have been caused by blade delaminations. Also, without divulging too much info, I have a very close relationship with someone who has trusted this machine with their life. This machine was extensively checked by the ATO, a competent engineer and, no-doubt, the student. What more could be done? This problem has existed for a long time now but no-one with the authority has chosen to be pro-active about a remedy. How often have you been frustrated by big companies who know about a safety issue but do nothing until someone is killed or maimed and then put on a big show of compassion and remedial action? All of this when acting on the obvious problem prior to an accident rather than making excuses or blaming others could have saved lives.
I don't fly them and never have, many of my friends, family and colleagues do, however. Your point about many other blades out there not delaminating may or may not be a little premature. Maybe we should wait and see after all the operators out there have checked their machines. I personally know of two more (R44s) which have been grounded due to signs of early stage delamination. In the meantime I shall try and take a leaf out of your book, your point was well made without anger or blame and I applaud you for it.
Helicopspeeder
Great post, well put and some very good points. My anger comes for a number of reasons. Chiefly the excuses that have been used and the blame game reulting from previous accidents which we all are pretty confident have been caused by blade delaminations. Also, without divulging too much info, I have a very close relationship with someone who has trusted this machine with their life. This machine was extensively checked by the ATO, a competent engineer and, no-doubt, the student. What more could be done? This problem has existed for a long time now but no-one with the authority has chosen to be pro-active about a remedy. How often have you been frustrated by big companies who know about a safety issue but do nothing until someone is killed or maimed and then put on a big show of compassion and remedial action? All of this when acting on the obvious problem prior to an accident rather than making excuses or blaming others could have saved lives.
I don't fly them and never have, many of my friends, family and colleagues do, however. Your point about many other blades out there not delaminating may or may not be a little premature. Maybe we should wait and see after all the operators out there have checked their machines. I personally know of two more (R44s) which have been grounded due to signs of early stage delamination. In the meantime I shall try and take a leaf out of your book, your point was well made without anger or blame and I applaud you for it.
Helicopspeeder
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Pandalet
excellent question. i was trying to find a picture of the blade profile on the RHC site for you look at, to no avail. and i am no artist.
If you can track down the the R22 Maintenance Manual Section 9 page 22A. all will be revealed.
The bit you see in front is the spar, leading etc , one piece.
At the trailing edge of that, for a distance of .5 inch top and bottom, there is a recess for the blade skin to sit snugly into and presumably just inside the exterior dimensions of the leading edge spar.
Within the skin of course is the honeycomb as witnessed above.
The problem, (to me anyrate) is that if the honeycomb is MIA then the skin will not be 'formed' as it should be and liable to buckle inwards whenever the resultant airflow presents itself as a pressure force, as in autos or~ dare I say it ~ the dreaded quick stop maneuvre.
I think the real answer to your question is that total weight was a limiting factor, and corners had to be cut (literally) where they could.
However I would very much like to hear someone from RHC answer your question.
While you are on the RHC site go to - customer support - publications - Safety Alert 4th Jan 2007 (I.E. before our oz incident) - then Service Letter 56. (dated March).
I wonder how many other "reports" referred to in the service letter, of others that there were????????? Another question for RHC.
FBG
That is an excellent point, one worth pursuing and perhaps a practice worth curtailing. As far as penetrants go they don't come much better than that old mosquito repellant stuff as such. I at least shall try to enquire as to whether it is also considered as hazardous to the glue that is used.
tet
excellent question. i was trying to find a picture of the blade profile on the RHC site for you look at, to no avail. and i am no artist.
If you can track down the the R22 Maintenance Manual Section 9 page 22A. all will be revealed.
The bit you see in front is the spar, leading etc , one piece.
At the trailing edge of that, for a distance of .5 inch top and bottom, there is a recess for the blade skin to sit snugly into and presumably just inside the exterior dimensions of the leading edge spar.
Within the skin of course is the honeycomb as witnessed above.
The problem, (to me anyrate) is that if the honeycomb is MIA then the skin will not be 'formed' as it should be and liable to buckle inwards whenever the resultant airflow presents itself as a pressure force, as in autos or~ dare I say it ~ the dreaded quick stop maneuvre.
I think the real answer to your question is that total weight was a limiting factor, and corners had to be cut (literally) where they could.
However I would very much like to hear someone from RHC answer your question.
While you are on the RHC site go to - customer support - publications - Safety Alert 4th Jan 2007 (I.E. before our oz incident) - then Service Letter 56. (dated March).
I wonder how many other "reports" referred to in the service letter, of others that there were????????? Another question for RHC.
FBG
That is an excellent point, one worth pursuing and perhaps a practice worth curtailing. As far as penetrants go they don't come much better than that old mosquito repellant stuff as such. I at least shall try to enquire as to whether it is also considered as hazardous to the glue that is used.
tet
I have been trying to think if any other helicopter I've worked on in the last 30 years has suffered from this type of failure. That is skin opening into the airflow in a sudden failure.
I can't recollect this happening. So if all the other manufacturers can keep there blades together with or without paint then I am sure that Robinson should be able to do the same.
I seem to think that Enstroms used to do something similar on the leading edge but this was always the result of corrosion pushing the skin up.
I can't recollect this happening. So if all the other manufacturers can keep there blades together with or without paint then I am sure that Robinson should be able to do the same.
I seem to think that Enstroms used to do something similar on the leading edge but this was always the result of corrosion pushing the skin up.
Originally Posted by Wilf
To build on Pandalet's excellent question - wouldn't mechanical fasteners augment the adhesive and potentially solve the problem?
I'm not sure this is a good idea. Usually when you sink threads or holes into a rotor blade spar, it's bad for fatigue. Maybe it would be a lot less at the tip.
Properly bonded materials tend to stay bonded. I've heard it said before that if it stays together, it was bonded. If it came apart, it was glued.
The enstrom has a similar, but simpler rotor section. A big honking extrusion, with a top and bottom skin bonded on, and the skins bond together at the trailing edge. The skins do not wrap all the way around the leading edge. The Hughes/Schweizer blades have a skin that wraps from tail all the way around the leading edge and back to the tail again. Still all bonded metal. They seem to stay together.
As several others have mentioned in this thread, it is suspicious that the HC doesn't look bonded to the skin. I think it was glued.
-- IFMU
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I would appreciate opinions on the WD40 or not issue.
I am a former B47 owner, where it was accepted that spraying or wiping every potential corrosion source with WD is good owner 'maintenance' (If you own a 47 and ain't buying WD in bulk, you're neglecting it..).
Now I'm the owner of an Astro I hear conflicting opinions on whether I should wipe the baldes with WD40. Of course WD40 should be kept well away from all rubber and elastomeric bearings on a Robbie and I never go near the head or T/R hub with it. But I'll tell you why I think it's a good idea: My Astro lives in a well ventilated (unheated) hangar and after a nightime temperature/humidity change, you can see regularly a line of condensation droplets hanging beneath the main blades. Guess where these droplets sit? Yes, bang on the bond line between the leading edge and lower skin. I've considered leaving the machine parked with a bit of pitch on, that will force these droplets back a bit. So this bond line, even in an ideal situation, is wet a lot of the time (add a bit of coastal salt to this and the result is obvious).
If the paint cover on the bond line is complete it probably doesn't matter, but I have recently adopted the routine of wiping the leading edge and lower surface with a sponge soaked in WD40. This reduces the condensation substantially and keeps the leading edge cleaner of flies in summer.
The whole problem with Robinsons, in my humble view, is not the machine, Frank, or the design, it's that they need a little more TLC in commercial and training environments than more (sensibly) over-engineered types. When is the last time you saw a training school with a routine for students cleaning blades? I'm also often horrified by the condition of some privately owned machines. If you adopt a 'kick the tyres and go' approach and leave everything to your engineers every 50hrs, it'll cost you in the long run.
The 44 is a very clever piece of engineering, built to a price and is one of the safest types flying - but it can't be abused like an old 206. The retreating paint edge must be flatted down gently every 100 hours or so - if you don't, the proud paint edge will be lost much faster and it can also cost you over 5kts. The outers of the blades obviously need painting when the retreating edge gets anywhere near the bond line. Only a fool would let it get that far. Unless you're flying regularly in rain or airborne sand, this is probably only necessary once between the 2200hr/12yr overhaul.
Lastly, I think my good old B47's unfinished stainless leading edge would be an improvement for R44 blades, but obviously Frank has his reasons for not doing that. The bond line where the paint starts is never disturbed because the paint edge is never eroding towards it. The 44's painted leading edge means you have to maintain the retreating paint line - if you don't, you're neglecting your machine.
So, WD40 or not?
I am a former B47 owner, where it was accepted that spraying or wiping every potential corrosion source with WD is good owner 'maintenance' (If you own a 47 and ain't buying WD in bulk, you're neglecting it..).
Now I'm the owner of an Astro I hear conflicting opinions on whether I should wipe the baldes with WD40. Of course WD40 should be kept well away from all rubber and elastomeric bearings on a Robbie and I never go near the head or T/R hub with it. But I'll tell you why I think it's a good idea: My Astro lives in a well ventilated (unheated) hangar and after a nightime temperature/humidity change, you can see regularly a line of condensation droplets hanging beneath the main blades. Guess where these droplets sit? Yes, bang on the bond line between the leading edge and lower skin. I've considered leaving the machine parked with a bit of pitch on, that will force these droplets back a bit. So this bond line, even in an ideal situation, is wet a lot of the time (add a bit of coastal salt to this and the result is obvious).
If the paint cover on the bond line is complete it probably doesn't matter, but I have recently adopted the routine of wiping the leading edge and lower surface with a sponge soaked in WD40. This reduces the condensation substantially and keeps the leading edge cleaner of flies in summer.
The whole problem with Robinsons, in my humble view, is not the machine, Frank, or the design, it's that they need a little more TLC in commercial and training environments than more (sensibly) over-engineered types. When is the last time you saw a training school with a routine for students cleaning blades? I'm also often horrified by the condition of some privately owned machines. If you adopt a 'kick the tyres and go' approach and leave everything to your engineers every 50hrs, it'll cost you in the long run.
The 44 is a very clever piece of engineering, built to a price and is one of the safest types flying - but it can't be abused like an old 206. The retreating paint edge must be flatted down gently every 100 hours or so - if you don't, the proud paint edge will be lost much faster and it can also cost you over 5kts. The outers of the blades obviously need painting when the retreating edge gets anywhere near the bond line. Only a fool would let it get that far. Unless you're flying regularly in rain or airborne sand, this is probably only necessary once between the 2200hr/12yr overhaul.
Lastly, I think my good old B47's unfinished stainless leading edge would be an improvement for R44 blades, but obviously Frank has his reasons for not doing that. The bond line where the paint starts is never disturbed because the paint edge is never eroding towards it. The 44's painted leading edge means you have to maintain the retreating paint line - if you don't, you're neglecting your machine.
So, WD40 or not?
WD 40 fell out of favour as it was found that after a certain period of time it abscorbed water. Spraying the internals of military aircraft with it was a common task in the seventies. I believe that the 40 stood for 40 day protection.
I have read that ACF 50 which does the same job and is aircraft approved does not abscorb water, but you would have to look into that.
I have read that ACF 50 which does the same job and is aircraft approved does not abscorb water, but you would have to look into that.
Thanks for that IFMU, you also reminded me about the other standard Enstrom problem, debonding trailing edges usually fixed by rivetting but also usually the writing on the wall for the blade as the split was usually followed by corrosion due to water ingress.
Your comment on the Hughes blades is a good point. Constructed from "front to back" you can't get them debonding into the airflow. Mind you the errosion of the unprotected aluminium leading edges used to be a problem on the older aircraft.Come to think about it I never saw a debonded trailing edge on either a 300 or a 500.
I would say that if you build a blade in the Robinson style (which is not unusual) the bonding has to be top class.
I still find it hard to accept that a layer of paint is the difference between flying and crashing. Modern aircraft design is supposed to be fail safe or at least fail in slow inspectable way. This failure was sudden and potentially catastrophic.
I wonder if blade tape might be a temporary answer to this.
Your comment on the Hughes blades is a good point. Constructed from "front to back" you can't get them debonding into the airflow. Mind you the errosion of the unprotected aluminium leading edges used to be a problem on the older aircraft.Come to think about it I never saw a debonded trailing edge on either a 300 or a 500.
I would say that if you build a blade in the Robinson style (which is not unusual) the bonding has to be top class.
I still find it hard to accept that a layer of paint is the difference between flying and crashing. Modern aircraft design is supposed to be fail safe or at least fail in slow inspectable way. This failure was sudden and potentially catastrophic.
I wonder if blade tape might be a temporary answer to this.
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From CASA today:
AWB 62-004 Issue 2 - Robinson Helicopter Main Rotor Blade Disbonding
http://www.casa.gov.au/airworth/awb/62/004.pdf
AWB 62-004 Issue 2 - Robinson Helicopter Main Rotor Blade Disbonding
http://www.casa.gov.au/airworth/awb/62/004.pdf
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"Preflight inspection of this area should allow early detection of a disbond before it progresses."
The helicopter at the center of this thread was inspected by not only the ATO but also an engineer the morning of the flight. If they can't pick it up who can?
This comes with news of a R44 with less than 50 hrs TT grounded because it failed tap tests on both blades.
The helicopter at the center of this thread was inspected by not only the ATO but also an engineer the morning of the flight. If they can't pick it up who can?
This comes with news of a R44 with less than 50 hrs TT grounded because it failed tap tests on both blades.
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My goodness a speech from CASA.
Their background notes seem to paraphrase what I have heard as the general thoughts on the subject, except to add that the eroded away bond line gap, between skin and spar, which may be up to a millimetre in width may have allowed a circular erosion especially in dusty conditions upon the leading edge of the already very thin skin, thus reducing its thickness.
From there I guess there would have to be further eroding of the bond material into the gap in front of the leading edge of the skin, extending to under the skin, to allow a wind gap and a now flimsy knife edge skin to be pushed into the airflow.
Far fetched? maybe. Seeable upon preflight? it should be.
Problem is there is 3000 sets of blades out there built the same way.
There is also a small number of cowboys out there who think that these blades are stronger and better and therefore will last longer than dash 2 blades.
Yep, we may read about them.
I believe that a mod has been done to 'tighten' the gap between the skin and spar and to allow for the leading edge of the skin to be pressed down further into a groove in the spar.
There was an inspection done 'by order' from ATSB before these blades left the country. I believe that ATSB have communicated, as one might expect, with NTSB, FAA and RHC. Stand by for another AD or SB.
WD40? cannot find anyone to support that idea, come to think of it why did we do it way back when, other than it being a 'practice' of tradition.
Just a soap and water wash down should have been sufficient each day.
Blade tape has been suggested, that is certainly my preference after re-painting, if required. I would favor a two piece kit such as we used to run on the 47's.
Of course no solvents allowed for cleaning gum off after the blade tape removal. I hear that eucalyptus oil will do the trick.
Also there has been some suggestion of using a harder two part marine primer.
Their background notes seem to paraphrase what I have heard as the general thoughts on the subject, except to add that the eroded away bond line gap, between skin and spar, which may be up to a millimetre in width may have allowed a circular erosion especially in dusty conditions upon the leading edge of the already very thin skin, thus reducing its thickness.
From there I guess there would have to be further eroding of the bond material into the gap in front of the leading edge of the skin, extending to under the skin, to allow a wind gap and a now flimsy knife edge skin to be pushed into the airflow.
Far fetched? maybe. Seeable upon preflight? it should be.
Problem is there is 3000 sets of blades out there built the same way.
There is also a small number of cowboys out there who think that these blades are stronger and better and therefore will last longer than dash 2 blades.
Yep, we may read about them.
I believe that a mod has been done to 'tighten' the gap between the skin and spar and to allow for the leading edge of the skin to be pressed down further into a groove in the spar.
There was an inspection done 'by order' from ATSB before these blades left the country. I believe that ATSB have communicated, as one might expect, with NTSB, FAA and RHC. Stand by for another AD or SB.
WD40? cannot find anyone to support that idea, come to think of it why did we do it way back when, other than it being a 'practice' of tradition.
Just a soap and water wash down should have been sufficient each day.
Blade tape has been suggested, that is certainly my preference after re-painting, if required. I would favor a two piece kit such as we used to run on the 47's.
Of course no solvents allowed for cleaning gum off after the blade tape removal. I hear that eucalyptus oil will do the trick.
Also there has been some suggestion of using a harder two part marine primer.
Join Date: Mar 2006
Location: St Louis, MO
Age: 46
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"No tape, nor WD-40 is allowed - they'll tell you that in the factory."
Agreed on the WD-40. It contains solvents, which you want to keep away from bonded surfaces. Also it becomes sticky as it drys and attracts dirt.
Agreed on the WD-40. It contains solvents, which you want to keep away from bonded surfaces. Also it becomes sticky as it drys and attracts dirt.