JuanRodriguez
Elite Veteran
Location: Rochester, New York
| First things first.......Check your blade axle as they are known to bend due to the violent woof you described..... If you don't check this and continue to diagnose, try this and try that, you are WASTING your time !!!
Secondly, if the heli has ever been involved in a crash, you must check ALL of the ball link screws that are up in the head, specially your blade grip ball screws..... They WILL bend and will not be noticable with a visual inspection.... You MUST begin to unscrew the screw in order to check them.... as you start to unscrew them, a bent one will wobble..... very visible !! This takes only a few minutes as you don't have to completely remove them in order to perform this check....... Again, if you don't do this you are again WASTING your time doing anything else because if you have a bent screw, it will unexpectedly cause your blades to go out of track in flight and it WILL cause the dreaded woof !!!
Thirdly, the other suggestions you received are good BUT.......
The reason you can get the "woof" when you overspeed is because there is slop in the control system.... you need to find that slop and greatly reduce and eliminate it.... Start at the pitch servo and ensure that it is FIRMLY secured in the frame !! A simple thing as a loose or slightly loose pitch servo can lead to the woof....
After the servo, check ALL of the linkages between the servo, pitch arm and the rest of the linkages between the swash and the head.... you're looking for slop. Check your washout arms... a worn unit can get quite sloppy and can cause problems.... Also check that the screws in that unit are tight..... Same goes with anything that pivots up at the head..... any loose pivot arm or component is not good !!
And lastly, go to the first step !! I want to stress the point that if your blade axle is bent, you need to find that and correct that problem first !! There are simple ways to check it but I would suggest you take the blade grips off and remove it so that you can roll the axle on a flat surface.... if it's bent or even slightly bent, you'll be able to "see and hear" it..... while you're at it, lube the dampners , re-grease your thrust bearings and AND MAKE SURE you install them with the washers in their proper orientation !! Installing them (or one) wrong can cause the woof too.....
Good Luck !! and let us know what you find ! |
