We’ve been keeping an eye on Steve Jobs’ private jet expenses ever since Morgan Stanley’s Katy Huberty recommended that her clients buy Apple (AAPL) based on how much time Steve Jobs was spending in the air.

The argument she made in Feb. 2008, after Jobs was reimbursed a record $550,000 for jet fuel and other expenses, was that he is “integral to negotiations with international carriers and supply chain partners.” (See here.)

Huberty’s reasoning turned out to be faulty. The company — and the stock — did just fine with Jobs’ Gulfstream V grounded for much of 2009 while he was recovering from a liver transplant and Tim Cook was running the company.

But it’s still fun to speculate what Apple’s CEO was doing in the air in fiscal 2010. We know he made trips to the East Coast in February to demonstrate the iPad to New York-based publishers, which might account for that $127,000 spike in Q2.

But how do we explain the $93,000 he racked up between June 27 and Sept. 25, as reported in the SEC 10-K form the company filed Wednesday?

Hint: The July family vacation in Kyoto, after which Apple PR assures us Jobs did not try to smuggle ninja throwing stars back to the states, doesn’t count. The company only reimburses business flights.

[Follow Philip Elmer-DeWitt on Twitter @philiped]