Mailing List lml@lancaironline.net Message #56508
From: William Rumburg <lancair403@verizon.net>
Sender: <marv@lancaironline.net>
Subject: Re: [LML] Re: Hydraulic Cylinder Rebuild
Date: Wed, 27 Oct 2010 06:31:18 -0400
To: <lml@lancaironline.net>
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Chris-
 
My shafts and cylinders were in perfect condition. I smeared the new O-rings with petroleum jelly prior to installing them on the end caps. The O-rings are a tight fit into the cylinders and I made a circular rocking motion while applying just enough force to insert them. My concern was possible damage to the O-rings when forcing them into the cylinders and across the snap ring grooves. I considered making sleeves from clear thin mylar in order to transition them into the cylinders and across the O-ring grooves without damage but didn't. Have you or anyone else tried that? 
All my cylinders are now 'bone dry' during test retractions.
 
Bill Rumburg
N403WR (Sonic bOOm) 
  
----- Original Message -----
Sent: Monday, October 25, 2010 3:09 PM
Subject: [LML] Re: Hydraulic Cylinder Rebuild

Bill,
That is the trick.
Once apart inspect the shaft very closely for scratches.  If there are any they need to be buffed out.  If they remain the weeping will return shortly.  The same goes for the ID of the cylinders bores.  Scratches here will lead to pressure leaking across the piston seal rather than the external weeping you mentioned.  Scratched will tend to damage new seals, so it is a good idea to remove them when everything is apart.
Chris
 
Chris Zavatson
N91CZ
30std

From: William Rumburg <lancair403@verizon.net>
To: lml@lancaironline.net
Sent: Mon, October 25, 2010 6:00:10 AM
Subject: [LML] Hydraulic Cylinder Rebuild

After ten years in service, all three door cylinders and two of the three gear retract cylinders on my 320 were 'weeping' fluid and needed rebuilding (Bill Harrellson said that his have been in service ten years with no sign of leaking and that mine are leaking because I'm not flying enough - he's probably right)
The three gear retract cylinders are manufactured by Wolstenholme Industries and neither I nor a couple of A&P's could determine how to remove the snap rings at each end. Eventually I saw how. Simply remove the hose fittings at each end and press the end caps a short distance into the cylinder to expose the snap rings and they're then easily removed.
 
Bill Rumburg
N403WR (Sonic bOOm) 
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