I hate doing things twice…. During landing gear retract testing, I discovered a small hydraulic fluid leak around the shaft end of the cylinder. Since I had replaced all the seals in the cylinder only a few months previous, I was curious to see what the issue was.
I removed the cylinder and took it apart, and on a very close inspection found that the seating surface for the poly-pak shaft seal had a raised area. Microscope inspection revealed that the very thin metal between the NPT tapped area for the fitting was pushed toward the seating surface and that there was a very small hole that was allowing hydraulic fluid to leak. No way to fix this – had to order a new end piece from the factory.