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11-01-2014, 06:53 AM
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Join Date: Oct 2014
Location: Sarasota Fl
Posts: 168
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anodizing
I work in the aluminum railing trade and use several coating methods but anodizing seems to be one of the better options. I havnt found much info on anodizing complete aircraft, either individual parts or sub assemblies, the company we use has a 20' x 4' tank. I would paint the exterior, anodizing does have insulating properties, don't know if this would affect anything. Any thoughts?
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11-01-2014, 07:24 AM
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Join Date: May 2006
Location: Pocahontas MS
Posts: 3,884
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I'm no expert, but I've read that anodizing reduces fatigue life by around 50%. Not a problem if the part is designed around that knowledge (RV spars are anodized), but could be a real issue if the part isn't designed with that life reduction in mind.
Charlie
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11-01-2014, 07:38 AM
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Join Date: Jan 2005
Location: Chandler, AZ
Posts: 2,904
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Not completely true
I spent some time with a company in Phx that does all types of coatings. One of their major clients is Boeing helicopters in Mesa. (The Apache) They anodize many parts for the Apache. He said the metal fatigue issue is part of Internet mythology and the overall affect is minimal. I also have a friend and RVer that is an engineer at Boeing helicopters. He said anodizing is not a problem in the fatigue area, but depending on what is anodized and the process it could fade in the Sun over time.
As has already been noted, the most critical part of our planes, the spar, is anodized. So, if you want to bling up a few parts with anodizing........
FYI, the company that is doing some work for me is Futureweld in Phoenix. My POC is Michael Beaver.
__________________
Darwin N. Barrie
Chandler AZ
www.JDair.com
RV-7 N717EE-Flying (Sold)
RV-7 N717AZ Flying, in paint
EMS Bell 407,
Eurocopter 350 A-Star Driver
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11-01-2014, 07:39 AM
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Join Date: Mar 2005
Location: SE Florida
Posts: 1,499
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Charlie is correct that anodizing reduces the fatigue life of aluminum parts by "up to" 50%. The Anodizing process makes the surface of the aluminum brittle. This is why the fatigue life is reduced. Fatigue life reduction is related to the thickness of the coating and the chemicals used. See
http://www.finishing.com/153/54.shtml
http://www.lambdatechs.com/documents/258.pdf
The insulating properties may or may not cause problems with using the airframe as a ground plane for your electrical system.
You might consider Alodining all the parts instead. No reduction of fatigue life with the Alodine process. The shop should be able to Alodine all the parts.
Charlie
Last edited by chaskuss : 11-01-2014 at 07:47 AM.
Reason: added web link
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11-01-2014, 09:51 AM
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Senior Curmudgeon
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Join Date: Sep 2005
Location: Dayton Airpark, NV A34
Posts: 15,420
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Welcome to VAF!
Jeremy, welcome aboard the good ship VAF 
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Mike Starkey
VAF 909
Rv-10, N210LM.
Flying as of 12/4/2010
Phase 1 done, 2/4/2011 
Sold after 240+ wonderful hours of flight.
"Flying the airplane is more important than radioing your plight to a person on the ground incapable of understanding or doing anything about it."
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11-01-2014, 04:38 PM
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Join Date: Jan 2005
Location: Chandler, AZ
Posts: 2,904
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5,000,000 cycles
[quote=chaskuss;929640]Charlie is correct that anodizing reduces the fatigue life of aluminum parts by "up to" 50%. The Anodizing process makes the surface of the aluminum brittle. This is why the fatigue life is reduced. Fatigue life reduction is related to the thickness of the coating and the chemicals used. See
The tests cited were for 7000 series aluminums. Not sure we use any 7000 in our planes. Also, failure was listed at 5 million cycles.
I think you guys are concerned about a problem that doesn't exist. As evidence, why are our spars anodized? Should we refuse them? Why aren't spars failing? Why are our AN plumbing fittings anodized blue? Should we be concerned?
I am very confident that the engineers at Boeing would not be anodizing Apache parts if this was a concern. Further, I'm confident that the engineers at Van's would not have anodized the most critical part in our planes, the spar system, if there was concern.
Again, if you want anodize some parts I believe it is safe and you're not likely to experience a problem. The internet is both a blessing and a curse sometimes.
__________________
Darwin N. Barrie
Chandler AZ
www.JDair.com
RV-7 N717EE-Flying (Sold)
RV-7 N717AZ Flying, in paint
EMS Bell 407,
Eurocopter 350 A-Star Driver
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11-01-2014, 07:36 PM
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Join Date: Aug 2006
Posts: 703
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Is the insulation property thermal or electrical or both?
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RV 7
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11-02-2014, 08:11 AM
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Join Date: Mar 2009
Location: Plano, TX
Posts: 2,089
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The way a safari helicopter crash some years back due to a control push-pull tube failure. The builder had anodized almost everything. The control tube failed due to fatigue cracking atributed to the anodizing. From what I have read, the issue is more of a concern on thin parts since the anodizing makes up a larger percentage of the cross section.
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Colin P.
RV-6A #20603
Complete 5/10/19
PP SEL / A&P
I donate every year on my B-Day (in Dec), but donated early in Sep'19.
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11-02-2014, 08:19 AM
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Join Date: Jan 2005
Location: Chandler, AZ
Posts: 2,904
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Hard anodizing
Quote:
Originally Posted by WingsOnWheels
The way a safari helicopter crash some years back due to a control push-pull tube failure. The builder had anodized almost everything. The control tube failed due to fatigue cracking atributed to the anodizing. From what I have read, the issue is more of a concern on thin parts since the anodizing makes up a larger percentage of the cross section.
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The Safari crash involved a couple of factors. He had the swashplate control tubes HARD anodized which wear better but makes the metal more brittle. There was a also evidence the control tube contacting the airframe.
Again, I don't believe you will have any issues anodizing parts for cosmetic purposes. I am going to call Van's on Monday and get the specifics of the spar anodizing and their thoughts on additional anodizing.
__________________
Darwin N. Barrie
Chandler AZ
www.JDair.com
RV-7 N717EE-Flying (Sold)
RV-7 N717AZ Flying, in paint
EMS Bell 407,
Eurocopter 350 A-Star Driver
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11-02-2014, 08:32 AM
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Join Date: Jan 2005
Posts: 269
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I wonder which is worst, spar corrosion or anodizing?
__________________
Adam Silverstein
Technical Counselor Chapter 643
Flying RV-8 10/30/07
PAID 2021
Pittstown, New Jersey
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