FAA mandates replacement of R22 & R44 main rotorblades

[Arrrj]

Rich B,

The short answer is yes. My 44 RII, with -7 blades (fitted as per the requirement around 5 years ago) have started to delaminate. To the extent they are U/S. I have to buy new ones. I am understandably not happy. It's flown on the east coast of Australia, Robbie are blaming the salt air.

I hope that helps.

Arrrj

[Spunk]

And we've been flying around with our -5 blades for a total of 2197 FH in a salty environment and are heading for the overhaul now to replace them with -7 blades. No delamination at all.

[etudiant]

Originally Posted by Spunk

And we've been flying around with our -5 blades for a total of 2197 FH in a salty environment and are heading for the overhaul now to replace them with -7 blades. No delamination at all.

Perhaps there is some peculiarity in the manufacturing process which produces these variations in the blade sensitivity. Materials are often poorly understood, so sometimes a processing step turns out to be detrimental rather than beneficial.
Finding out which is very difficult, especially with a flight critical component.

[Rich B]

Arrrj

Thanks for your reply. That does help.

Best Regards

Rich B

[blakmax]

Blade production processes

Originally Posted by etudiant

Perhaps there is some peculiarity in the manufacturing process which produces these variations in the blade sensitivity. Materials are often poorly understood, so sometimes a processing step turns out to be detrimental rather than beneficial.
Finding out which is very difficult, especially with a flight critical component.

As an adhesive bond failure forensics specialist, I am very familiar with issues relating to the -5 blades, but I was far more confident with the -7 blade processes, so I am very surprised and interested in comments about current disbond (NOT delamination, different fault, different cause) occurrences. Aarj, can you please PM me any details, photos etc. of these occurrences?

Before the suspicions start, NO, I am not a lawyer, journalist or other parasite and I am not a total Robbie basher. Google "A08_25_29 Recommendation" and realise that my input directly led to that report. My issue is that while it is regulated that for certification it is required that an OEM must demonstrate static strength, fatigue resistance and damage tolerance, but there is no current regulatory requirement to demonstrate that an adhesive bond must maintain structural integrity over the entire component (non-fatigue related) life. That is what the report finds.

Regards

Blakmax
Blakmax

[OttoRotate]

Here is the NTSB Safety Recommendation referenced by blakmax above:

https://www.ntsb.gov/safety/safety-r.../A08_25_29.pdf

[Old Dogs]

Originally Posted by blakmax

Before the suspicions start, NO, I am not a lawyer, journalist or other parasite and I am not a total Robbie basher. Google "A08_25_29 Recommendation" and realise that my input directly led to that report. My issue is that while it is regulated that for certification it is required that an OEM must demonstrate static strength, fatigue resistance and damage tolerance, but there is no current regulatory requirement to demonstrate that an adhesive bond must maintain structural integrity over the entire component (non-fatigue related) life. That is what the report finds.

Regards

Blakmax
Blakmax

I strongly recommend Blakmax's services.

He helped us with a Bell 212 main rotor blade debonding in 2006 that came very close to killing me.

[blakmax]

Hi Old Dog

You are too modest Old Dog. It was your excellent observation during pre-flight that saved your life. After that, it was pure chance that I knew the guy from DTA that was looking at the issue, and between us we worked out what was happening. A bit of cross-the-ditch cooperation helped.

Arjj, I'd really appreciate a PM with photos.

All the best

Blakmax

[[email protected]]

Could the difference between Arrj's and Spunk's blades be due to temperature and humidity since Germany and E Coast Oz are very different environments?

[blakmax]

Environmental effects

Hi Crab,

Firstly, the blades I have worked with were not in AUS but they were in a tropical island location, so your point is transferrable. The issue of bond degradation is related directly fly to hydration of oxides on the surface off metals, and the surface preparation processes used during manufacture. Ideally the preparation process will produce hydration resistance, but older processes only provide short term resistance, and the susceptible surfaces eventually hydrate and the bond dissociates, leading to disbanding. This process is more rapid in hot-wet environments where the surface is susceptible to degradation, but in reality the main issue is the ability of the production processes to prevent hydration. The reason I am not bashing Robinson is that there is no specific regulatory requirement for a manufacturer to demonstrate resistance to hydration.

If I could get photos of the failure surface, I could provide an assessment of the causes of bond failures.

Regards
Blakmax

[blakmax]

I sent you a PM

Hi Arrrj

I sent a PM. Please respond.

Blakmax

[aa777888]

Originally Posted by blakmax

Firstly, the blades I have worked with were not in AUS but they were in a tropical island location, so your point is transferrable. The issue of bond degradation is related directly fly to hydration of oxides on the surface off metals, and the surface preparation processes used during manufacture. Ideally the preparation process will produce hydration resistance, but older processes only provide short term resistance, and the susceptible surfaces eventually hydrate and the bond dissociates, leading to disbanding. This process is more rapid in hot-wet environments where the surface is susceptible to degradation, but in reality the main issue is the ability of the production processes to prevent hydration. The reason I am not bashing Robinson is that there is no specific regulatory requirement for a manufacturer to demonstrate resistance to hydration.

And this is why I need to check that there is paint over the bond line on the -5 blades every morning, correct?

[blakmax]

paint

Regrettably paint will not stop moisture absorption, it will only slow it for a while. The best thing about looking at the paint is that any disbond will cause fracking in the paint and that may* become obvious before the disbond becomes critical.

I thought that real;acement of -5 blades was already mandatory by now???

Blakmax

[Spunk]

I thought that real;acement of -5 blades was already mandatory by now???

EASA AD 2014-23-16 became effective on January 9th, 2015. The blades have to be replaced within 5 years of the effective date of this AD.

[MLH]

I have owned two 44's and managed to avoid replacing blades due to AD's. I will not own another Robinson product.

[Arrrj]

Blakmax...answered...Arrrj

[aa777888]

Originally Posted by MLH

I have owned two 44's and managed to avoid replacing blades due to AD's. I will not own another Robinson product.

Still the most affordable 4 place option even with these issues. Got a hell of a deal on mine because it had the -5 blades on it. Even after replacing them in a few months I'll be way ahead of the game capital cost-wise. If you can afford to own and fly a more capable aircraft than an R44 more power to you, but I can't.

[MLH]

Originally Posted by aa777888

Still the most affordable 4 place option even with these issues. Got a hell of a deal on mine because it had the -5 blades on it. Even after replacing them in a few months I'll be way ahead of the game capital cost-wise. If you can afford to own and fly a more capable aircraft than an R44 more power to you, but I can't.

You're making an assumption that the "new" blades are better in design than the old blades and that Robinson will not pull the rug out from under you with a future AD.

[aa777888]

Originally Posted by MLH

You're making an assumption that the "new" blades are better in design than the old blades and that Robinson will not pull the rug out from under you with a future AD.

The new blades are better, this is not an assumption. As for getting hit with expensive ADs, this can happen to any airframe at any time. Indeed, there seems to be a number of Boeing aircraft dealing with such issues right now. Hell, there were 43 FAA ADs issued in the last 60 days alone: https://www.faa.gov/regulations_poli...ss_directives/

[Rich B]

RHC issued these Service Letters last week.

https://robinsonheli.com/wp-content/...7/r44_sl70.pdf

https://robinsonheli.com/wp-content/...7/r44_sl68.pdf

As a result, I suspect we are going to see more reports of problems with corrosion, debonding, delamination, call it what you will.

Best Regards

Rich B