# ? about run-up on C206

I’ve noticed that when I do my run-up on my friend’s C206, I set the rpm’s at 1800, and cycle the prop to no lower than 1300. My friend mentioned that he will continue to maybe 1200 or so. We looked at the Flight Manual and it mentioned only seeking a drop, but not a quantitative figure or number.
My question to you is:

1. How much drop in R.P.M. is needed to cycle the propeller to make sure the oil is moving correctly?
2. How much is too much?
3. What dangers are there in either scenario?

Ron

Ron,

I don’t fly complex, but googled your question and came up with

group2.wawg.cap.gov/files/FOP_02.doc

Does 5A on page three of the Word document answer your question?

Allen

In most complex pistons I’ve flown, I’ve always tried to avoid a drop of more than 500rpm. Basically what you’re looking for, besides the oil pressure drop and manifold pressure increase, is the speed that the rpm drop happens. If you move the lever and it takes a couple seconds to drop 500rpm, either the oil is freeezing cold, or you should have it looked at.

I agree with cfijames on the 500 rpm max drop (just what I was taught, but don’t know if it can cause real damage to do more - probably not at low rpm/MP). One additional point I would add is that the amount of time it takes to drop can also be slightly longer when the plan hasn’t been flown for awhile. Oil has to move up into the prop governor to change the prop pitch and the oil drains out of it when the plane sits for awhile. Also, I learned to do it 3 times, the first time watching for a drop in rpm, the second time watching for an increase in manifold pressure and the third time to look for a drop in oil pressure (which can be hard to see on some planes).

I learned to do it 3 times, the first time watching for a drop in rpm, the second time watching for an increase in manifold pressure and the third time to look for a drop in oil pressure (which can be hard to see on some planes).

Thank you CA…you taught me something. I never heard that, but it makes sense.