9-Series Ring Mount (Suspension Frame) Rubber Mounts

Hi John,

"....I would never be comfortable pretending to be a structural vibration engineer and choosing one of those isolators for the 912. It would be a total crap shoot."

My training is in Agriculture (not a vibration engineer) - now retired. Starting with a sort of known - Sonex supplies Barry Mounts - I took a small risk and purchased the same mounts, in the next  harder durometer to help in controlling engine movement. I was prepared to go to the hardest rubbers in the range however this was not necessary.

"....I'd rather hear from people who have flown other rubber mount systems that work."

 My Sonex/Rotax 912ULS has been flying for 153 hrs - not all of it without tweaking and the occasional small problem (latest being the failure of the Rotax/Ducati Voltage Regulator).

I have, what I term the Sonex Mk2 Bed Mount /Aero Vee adapter.

The mount was fitted with Sonex supplied Hutchinson/Barry Controls 22001-13,  replaced with 22001-14 (harder) mounts, front pair 2mm shimmed to raise spinner/prop thrust and home made Cup Washers to assist in controlling lateral movement (especially at engine shut down).

Thrust is straight (no left/right adjustment). Engine is very smooth running with little noticeable vibration. Aircraft flies straight in Cruise, requires right rudder in Climb. I have a small (aproximately 50mm x 15mm) fixed trim tab, mid span, on the rudder.

A Ring Mount would have been preferable but now that the aircraft is flying so well, I doubt that there will be any change to the existing installation.😈

Sounds like you have a good setup. Do you have a voltmeter or ammeter that alerted you to the regulator failure?

The rubber for the new Sonex motor mount (interfaces with the Rotax ring mount) is apparently the same rubber used for the Sonex Jabiru motor mount. Mine are back-ordered but the word last week was they should be receiving the next batch this week. Can't wait to get it all put together.

"Do you have a voltmeter or ammeter that alerted you to the regulator failure?"

Yes - Dynon Skyview Classic has a volts/amps read out.

This does not diagnose anything however when volts drop from normal 14.2 down to 12 .3 and amps go down to -  3 amp and doesn't change with engine rpm, the pilot can deduce that the charging system is not working as it should. Various tests later, by my Electrical Engineer Son and with the all important body flexibility, to access the VR leads, diagnosed VR failure.😈