On C206 during take-off we experiance a surge upwards at full powerand stabilizes.? why and not at static?

Question

At maximum rpm after attaining 2700 rpm during roll,their is a notable change in sound of the engine,the engine rpm moves to 2850 and then falls back to 2700 this accompanied with rise in fuel flow to 24 and back to23 gallons which readings correspond. but at static it does not.everything looks stable no notable change in power , .manifold remains the same.The perfomance is good and the engine is 25hours since overhaul . just noted this recently when one of the pilots noted it

Answer 1

You could be adding power too abruptly. This is often the cause of a surge in rpm. You should smoothly advance the throttle from idle to full throttle over the count of about 5 seconds (one potato, two potatoes, three...). If it still surges, the prop governor or low pitch stops may need adjustment.

Answer 2

It does sound like the prop governor.  With the new overhaul, the oil pressure will likely require adjusting during the first several hours of break-in.  Since the oil pressure runs the prop governor, see if that needs adjustment and then check the oil flow to/from the governor.