Dampeners, Woof, Stripped Pitch Servo

[ClayK]

I don't know how I was able to get the bird down, but the fingers were on auto pilot and she managed to land just fine. Here's what happened.

Easy circuits, just warming up. Just finished a bank, was coming out and leveling off and settling in.... "WOOF!" blades fluttered for a quick second out of track. Almost sounded like covering coming off of woodies, only louder (I have on carbons, so I knew that wasn't it, but I'm giving a sound comparison). Lost some collective control, she was sluggish. I brought her in. Did some initial checks and I heard a servo "whining", shut her down. Pitch servo was stripped. Bummer was I had just done some PM the day before.... Some of the guys at my field were surprised I was able to bring her in with the servo all jacked up like it was, guess it was just my lucky day.

Looking at some threads and talking to some good sources tells me to replace the dampeners. They seemed serviceable last weekend, but :dontknow . Any other suggestions?

What dampeners should I use? Carbon Extremes were recommended, but which ones? I think CX11-00-005 are for the plastic head and the 006 are for the metal head right? Next time I just replace the o-rings on them right?

At least it's a good excuse to upgrade my servos to 9252's now...

[BarracudaHockey]

Remember what I said about 3151s?

The infinivation dampers are great for the Raptor.

Unscrew the ball screws on your blade grips and make sure neither of those screws are bent and check your spindle.

[Jim Platt]

Had a bit of the flutters with my R50 while at the Ft. Worth Heat Wave. We changed the head block ( loose on shaft), spindle, checked thrust bearings, and changed a couple of suspect links. Next flight fluttered again and when bringing it in to land at about eight feet the collective failed. Turned out to have sheared off the screw that holds the ball on the collective pitch arm. Amazingly, the 'copter just sat straight down hard and didn't damage anything else. Spindle was bent again. Changed it and replaced the TT 600 blades with 600 V2's and no flutter. Hummmm, now this thing has flown well with the TT blades for a while, so whats up? I installed a MA ball stud in the pitch arm, changed all the cyclic servo gear sets ( Futaba 9202's) and put the TT blades back on. No more flutter so far. Conclusion is that the V2's have a slightly more fwd. c.g. than the TT's and the servo gear train slop ( considerable) couldn't handle it. Any other quesses?
Jim

[ClayK]

Well, going to fault isolate the problem rather than just nuking it and hoping to fix it. Swapped out the servos, the 3151's are rather weak and that might have been the root cause to begin with. Put in the Duralite system since I was in moving stuff around. Put shims on the blade grip bolts (temporarily until new dampeners come in) to tighten up the dampeners. Going to fly a couple circuits and see how she handles. Depending on how she moves, I may swap out blades as the next possible solution (I've been flying these blades for awhile, don't know why they'd be a problem now). But I do believe that I need new dampeners, going to order those on Monday if I can get the correct part number.

Changed out my head block last weekend cause it was also loose on the shaft. Checked spindle, thrust bearings and changed some links a couple days ago. From what everyone keeps telling me, it's a dampener problem, but I can't figure out what I should be looking for in a pre-flight to see if the dampeners are bad....

[savage]

Had same problem. Went to the red dampeners and 9252. Never heard it for one flight, then I crashed. Still putting it back together.