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Bob Grimstead
Captain
Gender: Male
Location: Perth, Western Australia or West Sussex, England
Registered: Dec 2006
Status: Offline
Posts: 2028
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 Posted Wednesday, July 24, 2013 @ 06:30 PM
Hiya fellow Fournicators.
Please can anybody help me?
We have found serious exfoliation corrosion on the outer portions of both my British RF4D aileron's horns, so we have to make new ones, but I can't find what the material is -- although it's certainly aluminum (aluminium) and presumably 2024? but is it? and if so, T what?
That's Part No 4.12.04/H or component No 15 'Guignol d'aileron, Aileron Lever or Querruderanschluss' on Drawing No 4-12-01.
A detail on Drawing No 4-12-04 says that Drawing Nos 4-12-101 and 4-12-102 apply, but I don't have copies of those.
This horn/lever/guignol is fabricated from three separate components riveted together. The central portion, housing the pushrod bearing, is fine. It's the two outer parts that have deteriorated. They seem to be cut from extruded angle, perhaps 7/8" by 5/8" by 3/32" thick or 23mm by 16mm by 2.25mm thick (only roughy measured, paint still on, by Verynear calipers).
Can anybody tell me precisely what the material spec is? (No guesses, please, just facts. Thanks).
By the way, these components are hidden under the wing's trailing-edge, close to the ground where a) they're not easy to see and b) they pick up lots of spray, moisture, gravel and grit. I would seriously suggest that you all take a good, close look at them before you next fly. Losing your ailerons, or worse, having one jam, could significantly spoil your day. At first glance it just looks like a lump of dirt or grease adhering to one side of the forward edge of this component, but scratch it with your thumbnail and you'll see it's actually the material more than doubled in thickness or 'blown out' by powdery aluminium oxide corrosion.
Take care out there guys, and any help or advice would be greatly appreciated.
Yours, Bob (AOG)
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Flying and displaying Fournier RF4Ds VH-HDO and G-AWGN, building replica RF6B G-RFGB and custodian of RF6B prototype F-BPXV
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Donald
Command Sergeant Major
Gender: Male
Location: Scotland
Registered: Jan 2007
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Posts: 489
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Posted Thursday, July 25, 2013 @ 12:49 PM
Hi Bob,
Eugenio could probably tell you what the material is but you can get drawings through the French CFI web site. Here is a link to the plans list page which also tells you how to get the drawings you need, en Français naturellement.
http://www.club-fournier.org/index.php?option=com_content&task=view&id=69&Itemid=31
However, I don't see drawings 4.12.101 or 4.12.102 on the RF4D:
http://www.club-fournier.org/index2.php?option=com_content&task=view&id=64&pop=1&page=0&Itemid=2
Best I can do, I'm afraid.
Donald
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Markku
Master Sergeant
Gender: Male
Location: Kouvola, Finland, EFWB
Registered: Oct 2006
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Posts: 167
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Posted Friday, July 26, 2013 @ 01:14 AM
Hi Bob
The material is according to drawing AU4G, a French standard for dural alloy, should be similar to BS 2017 A.
I can send you a copy of drawing, if you give your e-mail address
Markku
[Edit by Markku on Friday, July 26, 2013 @ 01:38 AM]
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Bob Grimstead
Captain
Gender: Male
Location: Perth, Western Australia or West Sussex, England
Registered: Dec 2006
Status: Offline
Posts: 2028
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Posted Friday, July 26, 2013 @ 07:38 AM
Thank you very much indeed guys.
I knew somebody here would know.
my e-mail address is: bobgrimstead@compuserve.com
I am not familiar with either AU4G or BS2017A.
Is this similar to the American 2024 T3?
I look forward to seeing the drawing, and will post a photo of the corrosion when I can.
Thanks for the link to those drawings Donald.
I'm pretty sure that's the same list of drawings that I have on my computers, scanned from original blueprints a decade or so ago. Until now, I had assumed that this list was complete, but now I realise that some drawings are missing.
I guess that's life with a 45 year-old design.
Thank you both again, Bob
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Flying and displaying Fournier RF4Ds VH-HDO and G-AWGN, building replica RF6B G-RFGB and custodian of RF6B prototype F-BPXV
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Donald
Command Sergeant Major
Gender: Male
Location: Scotland
Registered: Jan 2007
Status: Offline
Posts: 489
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Posted Friday, July 26, 2013 @ 07:45 AM
Google is your friend and coughs up this page about French metals on Jodel plans and their equivalents: http://www.jodel.com/index.asp?p=materials&construction
Here's the relevant line | Quote: |  | | Aluminium alloys are :- AU4G Alum. with 4% copper. equivalent to 2024-T3 57 KSI UTS |
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Bob Grimstead
Captain
Gender: Male
Location: Perth, Western Australia or West Sussex, England
Registered: Dec 2006
Status: Offline
Posts: 2028
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Posted Friday, July 26, 2013 @ 01:02 PM
That's brilliant Donald.
Thank you so much again.
Even with this iPad, I still never think of searching for this stuff on t'internet. I guess I still don't really trust it, and prefer reference books or chatting with experts. In this case it was the LAA's Malcolm McBride, who said 2024 T3 was a perfectly acceptable substitute.
So I've ordered two feet of 7/8" by 7/8" by 1/8" (better slightly over- than under-sized) from Aircraft Spruce via Light Aero Spares, which seemed to be the quickest way. I did try three British suppliers, one local and two aerospace specialists, but neither had 2023 angle in stock.
So now I have to wait until the end of next week, which is extremely frustrating in this superb weather, but there are still plenty of other little jobs to do on Wagon, so I shan't be bored!
Thanks Guys. Fourniers and their pilots rule!
Yours, Bob
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Bob Grimstead
Captain
Gender: Male
Location: Perth, Western Australia or West Sussex, England
Registered: Dec 2006
Status: Offline
Posts: 2028
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Posted Friday, July 26, 2013 @ 01:21 PM
Donald,
I'm so delighted with that info, that I've now loaded both the Fournier Plans page and the Jodel site on to my iPad's home screen. As well as making interesting reading in the short-term, they will both be very useful reference sources in the long-term.
Again, thank you very much.
Yours, Bob
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Bob Grimstead
Captain
Gender: Male
Location: Perth, Western Australia or West Sussex, England
Registered: Dec 2006
Status: Offline
Posts: 2028
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Posted Sunday, August 11, 2013 @ 02:16 PM
... a little more information for everybody:
I have found that these aileron operating arms arms and their pushrods were only painted with cellulose dope. They are very close to the ground, and so they brush through long grass and odd high weeds, crop remnants etc. This acts like bead-blasting, wearing off the paint, and because all those plants in Britain were wet all last year, introducing moisture!
We tend to inspect that part of the wing from the rear, because that's the easiest way, but this corrosion can only be seen from the front!
And now I have been informed that French and German aluminium alloys of the late sixties and early seventies are particularly prone to exfoliation corrosion.
You have been warned!
Good luck.
Yours, Bob
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Bob Grimstead
Captain
Gender: Male
Location: Perth, Western Australia or West Sussex, England
Registered: Dec 2006
Status: Offline
Posts: 2028
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Posted Wednesday, October 16, 2013 @ 04:39 AM
Here at long last is a photo of one of the corroded aileron arms.
This corrosion is very easy to miss, because you tend to check that part of the wing from the rear, but this corrosion can only bee seen from the front... preferably with a torch, because it is dark under there.
Good luck Guys.
Yours, Bob
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Bob Grimstead
Captain
Gender: Male
Location: Perth, Western Australia or West Sussex, England
Registered: Dec 2006
Status: Offline
Posts: 2028
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Posted Wednesday, October 16, 2013 @ 04:51 AM
...and here's one of the nice new ones, made from thicker 2024T3, and bolted rather than riveted together for ease of future repair.
Oh, and painted with two-pack polyurethane this time.
Fournicating fabricating!
Yours, Bob
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eugenio
First Sergeant
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Location: Str. Val S. Martino inferiore 133/7 I - 10131 Torino ITALY
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Posted Thursday, October 17, 2013 @ 02:24 PM
Yes, but the rivets are aerodinamically and visually better ..... plus the fitting lasted more than 40 years, so also if riveted it wouldn' have posed problems.
Eugenio
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