why does the rpm goes pass the redline as the plane starts down the runway and not static on a airvan GA-8?

Answer 1

because as your speed increases the drag on the propeller decreases which makes it overspeed. so you have to reduce the throttle as you roll down the runway, especially if it's turbocharged.

Answer 2

Never reduce throttle on takeoff, and never hide anything from a mechanic. It might get you killed someday.

At full power with the aircraft static, the propeller might not be able to go into a low enough pitch to maintain RPM. This is not uncommon. As the aircraft starts moving forward, the forward velocity of the aircraft causes the AOA to decrease and as the RPM increases past redline, the governor should increase the pitch to absorb the excess power and maintain redline RPM. If the RPM exceeds redline and stablizes at a higher RPM, the governor spring force is not adjusted properly. Let your mechanic know that the engine is overspeeding and to what RPM. If it is a minor overspeed, they will simply adjust the governor set screw. It is very simple and takes only a couple minutes. If the overspeed is excessive, it may require an inspection.

Answer 3

Aren't you the same guy who burned up the brakes trying to land in less than 2000 feet in a crosswind?
If you are really flying that plane, it is truly messed up.
In no case should the rpm go above redline. That is what the governor is for. Get it fixed before the engine shells out and leaves you stranded.

Answer 4

Static, the props are pulling air and the load is high - once the prop starts moving forward the load is reduced.

Answer 5

have a mechanic look at it, but don't mention the overspeed. I bet the prop governor needs adjustment. And yes, its because of the lower drag as your moving. You know its not allowed to go into the red line, right