It’s actually a very easy operation. I believe an A & P mechanic who is familiar with your airplane, or with rebuilding struts in general will know how.
The service manual also has the procedure, although it generally describes a complete tear down and rebuild instead of just the strut O ring repack.
Jack the airplane up far enough to remove the strut tube, take a photo of the orientation of all the bolts, strut torque links, etc, deflate the strut and with a pair of 90 degree snap ring pliers, remove the snap wring at the bottom of the strut housing.
Depending on how high your jacks go, you may not need to remove the tire/wheel but I would remove the brake assembly and hang it so you won’t have to bleed the brakes.
Put down a drip pan, dis connect the torque link where they meet and slowly extend the strut tube. Fluid will bleed out of it so try to catch it.
After all the fluid has drained out, push the strut back up in the housing three or four inches then pull down hard, the O-ring holder will come out.
Not exactly how the wiper, the flat washer and the snap ring are stacked–you’ll need to know when you put it back together.
Order a strut packing kit from McFarlane Aviation, clean everything, inspect everything for sharp edges, burrs, and other problems. Correct everything.
The McFarlane kit will include more o-rings than you’ll need for a simple repack, but it will also have the correct ones and the wiper.
Install the o-rings being careful not to roll them into position, lube with something like DC-4 (most mechanics have this) or oil, position the snap ring and washer on the strut, then push the o-ring holder down over the top of the strut–make sure you keep it straight. It will take a good push to slide the holder onto the strut.
Then position everything to push the strut up into the housing, and slide the o-ring holder up into the strut. Move the rubber wiper and the washer up against the bottom of the holder in that order. You may need to tap on the holder to get it far enough up in the housing for everything to fit. Once the holder is bottomed in the housing–you’ll hear it, then put the snap ring in.
Then re attach the torque links. The strut will have to be service with hydraulic fluid. This is done by submerging one end of a flexible hose in hydraulic fluid and sliding the other end over the valve stem at the top of the strut. You will need to remove the valve core first.
Then you will push the strut up to the top limit, and pull it down until you no longer get any bubbles when you push it all the way up.
Once you’re to that point, install the valve core, let it down off the jack and service with air (nitrogen is preferred since it’s dry and will prevent corrosion). You will need a strut pump if you don’t have a nitrogen bottle since you’ll need at least 200 psi to start the extension.
That’s about it.
