Ah indeed you are right, and this exact point with 91.205 has come up on r.a.s. before, and as pointed out here in the past by others AC-21.17-2A precisely covers this.

http://www.faa.gov/documentlibrary/m...c_21.17-2a.pdf

Directly from that AC:

"Section 91.205 of the FAR. Powered gliders are considered to be powered aircraft for the purpose of complying with § 91.205 "

So to your point, except there is no flexibility here with no difference between a retracting engine self-launcher and touring motorglider etc. (and note as made very clear in this AC sustainers are also "powered gliders").


Thanks Daryl, I now see this has been discussed on RAS before, as you said. I had not seen the past discussions. I should have done a search for past discussions of this topic. The AC you point out is clear for motorgliders on the 21.205 compass question we are discussing.

However I note that the AC preamble says "this material is neither mandatory or regulatory in nature, and does not constitute a regulation". I assume that means the AC's guidance on 21.205 is open to a different conclusion? I think its arguable that the AC's guidance on 21.205 is inconsistent with the FAA definition of a glider as "a heavier than air aircraft, that is supported in flight by the dynamic reaction of the air against its lifting surfaces, and its free flight does not depend principally on an engine". This definition logically explains the otherwise-strange FAA view that a motorglider is a glider (even a touring motorglider). But following that definition, ie assuming motorglider free flight 'does not depend principally on an engine', a motorglider should more logically not be considered a 'powered aircraft' for 21.205.