Unporting?

I was reading Gann's "Fate is the Hunter" again the other day, and was
curious about the incident in the last chapter where he unintentionally and
naively avoided disaster by NOT slowing down when the DC-4 he was flying
from Hawaii to Burbank developed an unexplained occasional vibrational
"shudder". Later an engineer called him a very lucky pilot, and described
to him a scenario that he called "unporting" which was an uncontrolled dive
caused by lose of "balance" between the fixed and movable parts of the
stabilizer, which could not be recovered from. His plane had a missing
hinge bolt in the stabilizer, and had he reduced power, which was the
natural reaction to an unknown vibration, this "unporting" would have
occurred. Another plane on the same day crashed from the same phenomenon,
and all DC-4's were grounded worldwide immediately afterwards once this
phenomenon was understood.

My interest is the word "unporting". It doesn't sound right. I'm an
engineer (biomedical), but not an aeronautical engineer. You aerospace
engineers out there, is this the right term? Gann was not mechanical, and I
was wondering if he got the term wrong. If not, can someone explain how the
term is (or was, back then) used in aeronautical engineering? What is the
"port" it refers to? I'm curious.

--
Bob (Chief Pilot, White Knuckle Airways)

I don't have to like Bush and Cheney (Or Kerry, for that matter) to love
America