Converting Piper J-3 Shock Struts to Hydrasorb Struts

Converting Piper J-3 Shock Struts to Hydrasorb Struts by Gary Burkett Cookson, excerpted from Cub Clues #139 March/April 2007.

Download PDF: J3-Shock-Strut-Conversion-to-Hydrasorb.pdf

Converting J3 Shock Struts to Hydrasorb Struts

By Gary Burkett Cookson, OK

From Cub Clues #139 March/April 2007

Recently, I converted my J3 from standard shock strut landing gear to Hydrasorb type. This turned out to be a pretty interesting modification. First, the Hydrasorb shock strut is approved for the J3 per TCDS (A-691) item 216. Piper p/n 12843 has been superseded to 12998-00 for the complete assembly and can be purchased from Univair.

This was used on the PA-18-95 with 1080 HD shock cords. The modification has to be installed IAW (In Accordance With) Piper drawing #10534. I was able to track down the drawing from a Piper Service Center. The drawing itself was of little help but made the conversion legal with just a logbook endorsement. The length of the assembly is the same as the original.

As far as performance of the strut is concerned, it seems identical to the original, if anything; it should handle weight or a hard landing a little better. I have enclosed a photograph and a copy of Piper drawing 10534 for the Cub Club Library.