DF 140 RPM surge with loss of propeller speed.

[drobert383]

First time in running engine for a couple of months, started fine. 30 minute transit to lake at 1100 RPMs. When reached lake, slowly brought up RPMs. When reached about 3500 RPM's, engine suddenly surged past 6000 RPMs with propeller slowing. Felt like a slipping clutch on a car. Continued trying and it occurred twice more. On fourth attempt, all caught fine. Felt a little small variable in RPMs that I attributed to gas. The motor ran great the rest of day with no further issues with RPMs. Anyone with similar issues? Should I be concerned?

[Moonlighter]

Sounds very much like the propellor hub/bush is slipping. Typically it will grip at lower revs but as soon as you get enough load on it, the hub slips and you're the big revs but no forward motion!

Easy enough to get a new hub bush installed, that will fix it.

[drobert383]

Thanks Moonlighter. I thought it might be something a lot worse. Appreciate the quick response.