wjvail Senior Heliman Location: Meridian, Mississippi
| Alright Guys,
I had an 8411SA fail in flight the other day on my Raptor .50 Just doing a little work on my throttle curves and it did a quick roll to the right, a quick roll to the left and I hit throttle hold and it hit the ground on its' side... and sat there idling. I could hear the roll servo grinding away and thought at first I had stripped the (plastic) gears in the crash. A closer look and it was the motor that failed. The gears were fine. The servo had about a two gallons of fuel through it.
I called Horizon and they said they are seeing a higher failure rate on the digitals. They said that the source of the problem is their very tight gear train and near-zero dead band and the solution was to mount them looser in the gromets to introduce some play.:-((( I guess a lot of "control" vibration it getting sent directly to the servo motor. With this in mind I went out to look and my heli. I found that while the controls didn't bind, the servos didn't buz at idle, there was NO slop. Further, I found that my swash plate (a Quick UK unit) was a little tight in spots around the ball and may have been working on the servo some.
I replaced the damaged servo AND the pitch and collective servo. Thing is, the only servos I had on hand were 3 NEW 8411's! I've got 2 helis with 8(!) ($800.00USD!) of these servo's and can't affort to go out and buy 8 new Futaba's right now.
I want to go flying today but I spend the entire time expecting the thing to take off over the horizon with a failed servo.
I need to here some good stories about these servo's. I need someone to tell me there are 296 of them in their club, some with 500 hours on 'em, and none have failed. I need someone to tell me they have 8 of them in two heli's with 150 gallons of fuel through each and so far so good. I flew a 1/2 gallon throught my X-Cell yesterday and didn't have a problem. Did I get lucky and am a flight away from some disaster or should I expect another 100 hours of trouble free flying?
As a side note Horizon did NOT ask for a list of broken parts to my Raptor so they could replace them!
You know, the first thing I want in a servo is reliablity. Everything after that is gravy. This zero dead band is great right up to the point it it hits the ground and the parts start flying.
Your respecfully, and stuck in heli hell,
Bill Vail |