noooby
Perhaps we should be saying "unknown composite airframe stress".
I used to stand at the hangar door in Macau, watching the aircraft (C+) depart using our vertical departure procedure. I would essentially be almost directly underneath the aircraft and so had an amazing view of the stresses the entire tail section was enduring using this procedure. Trust me when I say, it made me cringe to see just how much bending and twisting was going on all up and down the entire tail boom. Lets remember this was all happening on an airframe design with many, many years of service already behind it.
Somehow I don't think the same can be said where the 139 and its composite structure(s) are concerned.
JW