Originally Posted by kcaldwel
If changing the motor thrust line affected the power-off dive test results, it must have been out of trim in glide before the dive test. The dive test is only meaningful at all if the airplane is in trim near best L/D speed for a hands-off glide.
A better test for CG position is inverted flight. The amount of down elevator required inverted for level flight at the same speed as upright is a good indication of the stability margin - less down elevator, lower stability margin.
Thrust issues are easy to confuse with pitch trim and stability. The pattern guys have systematic trimming routines in a particular order to sort out which is which.
Yes I believe it was, having tried to get the pitch-up-on-power corrected, it seemingly was still trimmed nose down for the dive test which exacerbated the effect. Giving some up thrust I think has effectively given a bit of up force to the HS when adding power so negating a bit of the pitch up.
Anyway thanks for all the advice and info, hope this can also help someone else with a similar issue.