2200 TRIGEAR ENGINE MOUNT CRACK

[Jim B]

I have 325 hours on my trigear configured 2200 jabiru sonex. I converted from standard gear at 122 hours. So I have 203 hours on the trigear mount and approximately 700 landings. During an oil change and my 25 hour maintenance on the heads and valves I found my lower left spool cracked all the way through near the weld. I do look at the mount every time I have the cowling off and have never found anything wrong until now. It did surprise me somewhat. I have heard of 3300s having cracked engine mounts but never the 2200. The factory tells me it is repairable so now the fun begins.

[peter anson]

Hi Jim, good thing you found it. See https://sonexaus.wikispaces.com/file/view/Trist_outback091509%5B1%5D.pdf for a similar case. The relevant part is about halfway through the document if you don't want to read the whole story. At some stage Sonex changed the tubing thickness from 0.035" to 0.049" but that is still a real weak point in the mount.

Peter

[Kai]

Same happened to me on my standard gear Sonex #0525 with a 22A. It is so old that it has the engine mount with the thin walled tubing. At apprx 500 hrs the lower left support broke. Repair was much like shown in Stuart's narrative (great, by the way): just a little inside dressing with a 1/2" round file, one long high grade steel ø14mm pipe with 2mm wall thickness rammed down the mount structure, with liberal amounts of high temp Hysol, after cleaning and degreasing everything inside-out. It has been sitting there ever since. To quote Kerry: "Grass fields- certainly. But rough grass fields- no!". Watch your labding gear retainer bolts!

[Jim B]

Peter/Kai
Thanks for your replies. The factory refered me to the 3300 trigear engine mount SB dealing with cracked mounts. It looks encouraging especially since reading what Stuart did to repair his during a long cross country trip. The factory SB is basically welding a splint on both sides of the crack. Now to remove the engine and get the mount off the plane to make the welding easier.