IMC and Rotax engines

You'll need the minimum equipment (FAR 91.205), proper airworthiness, required IFR equipment inspections (pitot-static system - FAR 91.411, transponder - FAR 91.413, VOR checks), GPS updates, etc. Obviously, you'll also have to be legal and rated. 

Thanks Jason - that's my understanding as well.  But is there anything related to the engine that would prohibit IMC or need for certification?  I don't think there is, but given I've run into this a number of times I'm trying to find any clarification at all.

Hi Brian,

I have never heard of an engine needing to be specially certified for entry into known IMC. As I understand it, any adverse effects from IMC such as icing, etc on the engine are covered by the airfame's certification. There is no reqirement for carburettor heat in Part 33; that's covered by Part 23.

All of the certified four-stroke Rotax engines (except the 912A) are certified to 14 CFR Part 33, just the same as the newer (certified post-1965) Lyconental engines. In fact, because the Rotax engines were certified more recently than most of the Lyconentals, they have to meet the more stringent reqirements of later amendments of Part 33. Some varieties of the Lyconentals still only have to meet the certfication standards applicable in the 1930's. If you're interested, here's a link to the US TCDS for the Rotax engines on the FAA's website:
https://drs.faa.gov/browse/TCDSMODEL/doctypeDetails?Status=Current&TC%20Holder=BRP-Rotax%20GmbH%20%26%20Co%20KG

The non-certified versions of the Rotax engines are technically identical to their certified counterparts. Although my grasp of the US regulations around the operation of E-AB aircraft is a little shaky (I'm in Australia and I'm not a lawyer), it's my understanding that as long as the Part 91 requirements for IFR are met and the Limitations section of the aircraft's Special Certificate of Airworthiness permits it, you should be able to (at least from a legal standpoint) fly any E-AB into known IMC, regardless of engine type.

Just to prove that a Rotax-powered aircraft can legally enter known IMC, here's the US TCDS for the Tecnam P-Mentor:

https://drs.faa.gov/browse/TCDSMODEL/doctypeDetails?Status=Current&TCDS%20Number=A00067IB

(There's nothing particularly special about this aircraft, it's just the first Rotax-powered aircraft I could find on the FAA's DRS site)

Note that while entry into known icing is prohibited in this aircraft, it is specifically approved for operations under IFR.