Speculation: The training market is the 800lb gorilla in GA. Almost
every certified design is going to get a lot of business from schools
and whatnot. This includes twins too, where people are always trying
to get the coveted multi-engine ratings.

Enter the Skymaster: It's a twin, which means it has the cost of a
twin (in fuel and overhaul costs and insurance, etc). Unlike most
other twins, though, when you do your multi training and checkride in
it, you have a limitation in your logbook to inline multis, right? Eg,
you can't go and fly a 310 without another checkride.

With this in mind, I would guess that most schools, upon learning about
the restrictions, passed on them because all those aspiring airline
pilots wouldn't be interested in wasting time with inline multis.

Basically, I'm guessing that safety benefits of an inline are
overshadowed by the practical usefulness of the logged time towards an
ATP (in the eyes of the schools and students, a significant market).

/conjecture

Thoughts?

Ben Hallert
PP-ASEL