2nd Throttle Servo Failure..............Maybe?

[Kepstang]

It appears that I have just had my second throttle servo failure and am now trying to figure out if it is just a coincidence or something else. Each servo lasted about 8-10 flights which consisted mostly of FBL adjustments and governor tuning issues that I had to work through. It very well could have been a bad first servo or it was just not up to the task or suitable for a vibrating environment. The second servo having been used from a friend just decided to take a dive around the same amount of flights?

The first servo was a Spektrum A6150 HV and was brand new. The engine just died in the air and auto'd down. The throttle servo arm was about 15-20 degrees past it's low limit, forcing the linkage over center and it was smoking.................

The second servo was a Torq BL9080 HV, was a good (at the time) used servo that a friend had around. It began twitching high/low very quickly in the air. Once on the ground, it continued the same rapid high/low twitching regardless of the IU setiings or throttle hold settings and no smoke yet ..............................

My setup is as follows:

Spektrum DX18
Savox 2271/2272 servos cyclic and tail
Toxic VX270TT engine
Vbar Silverline 5.3 Pro and two Spektrum sats
Using the Vbar Gov.
Stator Gator with white wire feeding Vbar sensor input.
Stator Gator powered by Vbar servo output right next to the sensor
2S Lipo flight pack feeding power to the Vbar
Three IU settings for three head speeds. 1100, 1400 and 1850 RPM
No normal mode. I come off of hold with a slow ramp up to 1100

GOV I Tab:
Vbar gov selected - nitro combined
Channel from receiver - CH1/ESC/Preset
Output socket on Vbar - Collective/ESC

GOV II Tab:
Throttle servo adjustment is -100 and +120 (wanted the most resolution possible) and has absolutely no binding at the carb stops.

I'm thinking that this is just coincidence and should have just used a brand new servo but what are the chances that both servos lasted about the exact same amount of time? The only other possibility that I thought of was that the ESC/Collective channel was analog however Vstabi says that only digital servos are to be used so I have to shelve this variable?

Thank you in advance for your thoughts!

[Laughingstill]

Vibes killing the servos? I am unaware the specs of those servos but are they the correct frequency?

[Kepstang]

OK all. Found out that the A6150 HV servo was not actually digital. Explains what happened to that one. I should have double checked it when I picked it up from my LHS but "assumed" he gave me what I had asked for.

The BL9080 is digital and is 200Hz and 1520. I do have never seen a parameter within Vbar that asks for the servo frequency for a throttle.

Anyway, we are back to a failure that has nothing to do with one another and the second failure was more than likely just an old servo that was destined to fail anyway.

I just picked up a Savox 1267SG and will install it and fly reliably....... thumbs crossed.

[TheBum]

Throttle servos are treated like cyclic servos: 1520us only.

[Kepstang]

The new Savox ought to work. Made a dumb mistake with the local hobby shop provided servo not checking it. Assumed that it was correct especially being a HV servo. Then using an old servo that flamed out just made me question what was going on.

Nice day here and will be off to the field shortly to put her back up.

[whitehedr]

Heli pilots at my field told me that the throttle servo should be matched to the cyclic servos for best performance. I have 4 RJX HV servos on my machine and a new BK replacement for the original RJX HVtail servo that failed on me in an intermittent way.

ROG

[Kepstang]

Everything has been good with the new throttle servo. It was just a case of the wrong (analog) servo at the beginning ( my fault for not checking what was sold to me as a digital) and a used servo that was destined to fail anyway. Flew today with no problems and now have 18 flights on this servo with no problems at all.

[whitehedr]

That is good news!

ROG