I will echo Charlie's comments, going with an alternative engine involves considerably more work than the level of Van's Rotax integration. If you are a gearhead and like custom fabrication, along with using your imagination to make something better or solve a problem then it can be a fun experience. In my case it added three years to the build and at the end of the day most likely cost as much as putting in the Rotax if you include the extra hanger rental time for a non-flying aircraft. For me, the experience was worth it.
- custom fab work? YES, lots of glass work on the cowling, fuel and electrical are all custom fab items. Expect cascade effects on making changes for other systems (see pitot tube in next item).
- lack of Vans support: Not an issue for me, Van's will neither confirm nor deny anything if you ask them a question on an RV-12 EAB build. The only helpful direction was do not drill the spar web for two pitot bulkhead fittings and see AC-43.13 if you want to add a battery access hatch in the tailcone.
- effect on CG: The CG will move forward and the empty weight will go up by about 80-100 pounds. Do not be fooled by anyone claiming light weight vs Rotax.
- DAR inspection issues: Vic S was my DAR, no issues with the engine.
- insurance issues: None so far.
+AOG: You are really on your own if you have engine issues and are away from homebase. I have a lot of spare parts on the shelf to handle anything other than a catastrophic engine failure.
In hindsight, today the only thing I would have done different was to build an RV-9 vs the -12, mainly because the extra weight and CG has more margin with the RV-9. The AM15 might be an interesting combination for the RV-9.
John Salak
RV-12 N896HS (Honda Viking 110)