Centurion U/C Repair - RC Groups
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Aug 18, 2017, 01:21 PM
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Centurion U/C Repair


I need to fit a new insert into the top of a half-inch diameter Centurion undercarriage leg, but cannot extract the old one. I have removed the roll pin and the central peg, but the outer part is stuck in the top of the tubular leg. I am thinking of applying heat but don't want to damage the piston seal; am also mindful of the spring held in compression by the insert. I'd be grateful for any advice from others whose landings are less than perfect and who have successfully carried out this repair.
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Aug 19, 2017, 02:37 PM
An itch?. Scratch build.
eflightray's Avatar
I haven't a clue what you are looking at, how about a picture or two.

Is it a Cessna 210 Centurion, or a tank ?

Ray.
Aug 21, 2017, 06:38 PM
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Centurion U/C Repair


Hello Ray, thanks for responding.
Centurion is a brand of retractable undercarriages for model aircraft. Mine is air actuated up and down, installed in a Topflight Seafury.
I have attached some photos as requested.
Aug 22, 2017, 03:00 PM
An itch?. Scratch build.
eflightray's Avatar
Looking at the design, I would have assumed the insert wasn't meant to come out, otherwise all the load would be on the thin wall tube.

If you are just replacing the top part that connects to the retract, I wou;d be tempted to 'fix' a replacement in. 'Fix' as in, glue, solder, weld etc.

Or if you are having a new one made, (mate with a lathe ?), make it slightly over size, and re-drill the 'socket' to suit.

Couldn't find anything on Centurion retracts/oleo legs with a google search.

Hobby King do a big range of oleo legs if ever you need to replace it.

Ray.
Aug 22, 2017, 06:07 PM
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Cougar429's Avatar
I've done mods on many Robart and other makes and that does not look that unusual. If like many you can undo the scissors and remove the bottom half of the strut and spring, (be careful if each pivot pin is held with a tiny "C" clip). This should allow you to use a punch or drift to try and knock out that insert.

If that does not work a heat gun is another option if Loctite was used to retain the sleeve.

Only other problem would be if the maker soldered that sleeve into the tube. Unfortunately you would need much more heat to remove it and that may affect the strength of the tube.

ps. That already looks pretty chewed up, so you really have nothing to lose.
Aug 23, 2017, 04:07 PM
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Centurion U/C Repair


Ray - I have decided to fix a new top part (peg) into the existing slightly damaged insert, as I have done in the past, despite the spares obtained some time ago being combined units, which I have managed to separate. This after finding the original instruction leaflet which forbids removal of the insert from the top of the strut as "a compression spring will be released, causing personal injury", so you are correct in assuming they are not meant to come out.

Cougar429 - There seems to be another sleeve fixed in the bottom of the leg, to act as the extension limiter, so I've taken the easy option - again!

Thank you both for your help.
David


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