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What is SB-912-079???
- Thread starter Amadeus
- Start date
Yeah-- what a "grab bag" of directives! (I sense lawyers in the background). Each part of Section 3 (the heart of the document), parts 3.2 through 3.18, has tasks for Operators and for Maintenance people. Some of the directions are very general, others very specific. Some are old news ("increase rpm before mp"), others won't apply to you (e.g. since you have a -iS engine, every part about carbueretors, which I still can't spell even though I've overhauled them for 50 years). I plan to go through with a highlighter to mark the portions that apply to me.
Looks like an attempt by ROTAX to cya for non-standard installations and reminder to OEMs and owners to operate the engine correctly. Yes I agree not much new for an RV-12 owner in this but I imagine there are many engines being misused in everything from aircraft to airboats. Basically illustrated by the stated requirement and reminder to OEM's from ROTAX that a MAP gauge be installed and operate the engine per the graph on pg 12.
Reading the bulletin I am struck by the amount of "this is the way to run the engine" instructions are in it. If nothing else its a good primer on what you should see and do on inspection and flying.
My interpretation is this SB is only applicable for "912 S/ULS (Series)", and none of this would apply to a 912iS. But I'm fairly new to SBs and could be mistaken...
As others have implied, I believe this only applies to the 912 S and ULS engines with carburetors. I suspect there will be a similar SB on the way for the 912iS.
Much of it is directed at the OEM, Vans in our case. They may issue follow on SBs, though as has been stated, much of this is ‘old news’
Also, much seems to apply to constant speed props, and/or engines with carb heat, also not a concern for the majority of us.
The recommended starting procedures on page 31 were interesting and good. On the checklist and in the training I received at a nearby flight school on the RV12, it wasn’t this clear that cold start should be done with throttle completely closed. After Rotax and LSRM training though I completely understand why that is now.
I may need to go to one of the Rotax classes. It would be nice to know more about the 912iS before I start flying behind it.
Reading through the SB, there appears to be several items that are intended to help prevent detonation. My initial assumption was computer controlled timing on the 912iS would have a knock sensor and adjust the timing as needed to prevent detonation. But after a quick Google search it appears that may not be the case. According to forum posts... earlier 912iS came with a knock sensor that was never enabled for ignition timing, and later models don't even have a knock sensor. It would be interesting to talk with an official Rotax source and see if this is true, and what made them decide not to go ahead and enable the sensor.
Reading through the SB, there appears to be several items that are intended to help prevent detonation. My initial assumption was computer controlled timing on the 912iS would have a knock sensor and adjust the timing as needed to prevent detonation. But after a quick Google search it appears that may not be the case. According to forum posts... earlier 912iS came with a knock sensor that was never enabled for ignition timing, and later models don't even have a knock sensor. It would be interesting to talk with an official Rotax source and see if this is true, and what made them decide not to go ahead and enable the sensor.
I can confirm the knock sensor, if installed, is not enabled, on the 912iS. I do not know the reason why this is the case, only that it is the case.
I definitely recommend taking the Rotax iRMT Service level class even for operators who have no intention on doing their own maintenance. If you have any interest in it, the Maintenance level is also information dense and useful. There are things about this engine that are not obvious or intuitive.
I think you're right, that this applies to the ULS and not the iS engines -- which would explain why there is no content specific to the injected engines, while much of the info refers to operating the engines with carbs.
