I could be wrong since I didn’t do mine that way, but I think the idea was to keep the inner radius “dry” just for the purpose of installing the assembly into the actuator (get past the snap ring groove, etc).  Thereafter, the O-ring should have some contact with the hydraulic fluid or could be lubed through the hole for the 90 degree fitting before installing the fitting.  By the way, I performed a complete rebuild on one of the main gear actuators due to a leak at the rod end of the cylinder – that requires replacement of about a half dozen seals and surely tests one’s technique and patience ….

I also had to clean up the snap ring groove with sandpaper as I burred it up a bit when removing the ring.  I was more careful on the other two.  Below is another tip I received from a fellow Lancair pilot:

 

Keep the o-ring and its groove dry and free of oil and grease except for the outside of the o-ring that will contact the actuator cylinder.  On that surface, apply the hydraulic oil or the grease they recommend.  This procedure is supposed to keep the o-ring from trying to roll out of its groove when sliding the assembly into the cylinder, but still supplies lubrication for the o-ring to cylinder interface.  I received this tip after I had already rebuilt mine, but I do recall my O-rings trying to squirt out of their grooves during installation.  Good luck!

 

Dana

Dana Westphal

Legacy RG N97DW

 

From: marv@lancair.net [mailto:marv@lancair.net]
Sent: Tuesday, July 09, 2013 3:31 PM
To: lml
Subject: Re: [LML] Overhauling Landing Gear Actuators

 

Posted for Chris Zavatson <chris_zavatson@yahoo.com>:

> Pete,
> Your groove must have a small burr or similar grabbing the O-ring.  I
>suggest some fine wet/dry sandpaper to knock down the edges of the O-ring
>groove.  I use a home-made polishing/honing tool made of wet-dry strips that
>takes care of this when I clean up the inner bore.  By hand should work
>also.  400-600 grit if you need to take material off.  Down to 1,000 grit for
>finishing.
> And of course lots of Parker O-Lube helps also, but this will not make up
>for a burr. 
> see also
>http://n91cz.com/Hydraulics/Rebuilding_Lancair_Hydraulic_Cylinders.pdf
> good luck,
>  
> Chris Zavatson
> N91CZ
> 360std
> www.N91CZ.net
>
>From: CavittP <cavittp@aol.com>
> To: lml@lancaironline.net
> Sent: Tuesday, July 9, 2013 5:15 AM
> Subject: [LML] Overhauling Landing Gear Actuators
>
>
>
> Any hot-tips on how to replace O-rings in landing gear actuators?  I'm
>having a hard time not causing damage getting them past the snap ring
>grooves.
>
> Pete Cavitt - N320PL
> +1-619-701-0784 Cell
> http://www.petecavitt.com/
>
>>>