gene maurice

I had a strange servo failure the resulted in a fly-away crash of a Peak 26% Sbach 342. As mentioned the plane was a Peak 30cc size Sbach 342, 12lb., with an OS 160FX, JR 8231's on the ailerons, a single JR 8411 on the elevator, JR 3121 on the throttle, and a Savox SC-0251mg on the rudder. Power was supplied by a 2 cell 1700mah li-po thru a Castle 10a switching BEC set to 6.1v. Receiver was an Orange R820x. All of these components had many flights on them except the receiver, it was new. The battery was less that a year old with 21 cycles.

On the third flight of the day, preflight battery voltage was 7.8v with a 3a load. Flight was completely normal until 6 min into it. I was performing a Triangle Loop, ½ roll, positive snap, 1/2 roll. As I came across the top at reduced throttle just as I started to move the sticks for the snap the plane went to full throttle. I pulled the throttle back; nothing. Thought, OK lost throttle servo, linkage, something; so I’ll fly around till I run out of fuel. I started to bank when the plane locked at about a 10 degree bank and at that point I had no control. The plane did 2 1/2 circles before running out of altitude.

I was able to recover all of the electronics. The throttle servo was completely destroyed and the battery was mangled. Everything else was intact. At home I went thru the process of trying to identify the failure point. Amazingly the mangled battery was still putting out 7.7v on a 3a load. The regulator was still spot on 6.1v. The receiver functioned normally and even went to low throttle with loss of signal. I plugged in the servos one at a time with the Savox being the last one. As soon as I moved the rudder control the receiver went dead, voltage at the receiver went to 0v. OK gotta be the receiver, NOT.

I put a Turnigy Power meter between the regulator and a servo tester, setting it to cycle mid speed. At random points the servo would draw 10 to 12.5 amps!!! This caused the 10a regulator to cut out to 0v and would reset after the load was removed. I disconnected the regulator and went to a straight 5 cell NiMh 3300mah pack to try and figure out if it was electronic or mechanical; it continued to randomly peak at 10 to 12 amps. The servo was getting fairly hot and finally quit completely after a couple of minutes of testing.

My resulting theory is an electronic failure in the servo digital circuitry caused the extreme current load. In this case it was fortunate that the fly-away crashed in an empty field with no personal injury or property damage. There but for the grace of God………………………………..

Dick T.

My Feedback: (243)

At least you were able to find the culprit rather than having a box of components with zero confidence remaining. It is always tough to loose a plane especially one in this size range and investment.

It points out that the high reliability of today's components is not bulletproof. Sorry for the loss but at least you know why.

TFF

There is a scale builder/flyer that puts, i think, diodes on all the servo wires. He had more than one a giant scale plane have the servos short out the radio and loose a plane. One I think caught fire in the wing, and this was before all the different brands today; bout ten years ago..

gene maurice

Dick T. - Yes I'm glad I know what caused it. If not ALL of the components become unreliable, read unusable.

BarracudaHockey

My Feedback: (11)

Sorry to hear about your wreck.

Components fail, I have that servo on a model with over 200 flights, luck of the draw, doesn't mean that model servo is bad.

The Saylors

I think its a rash of a bad production run. My cousin has gone through two of those in a month. Both burned up in a few runs. They would start turning very slowly and then quit, then have a nice cooked smell to go with it. Luckily we were playing with the cars so there wasn't any crashes but it still blows to have a break down. Usually savox does good but it seems someone got a little lazy recently, hopefully they will remedy the situation. Sorry your plane sploded, i know how much that sucks.

gene maurice

Barracuda Hockey - I didn't say it is a bad product, I just stated I had one that failed catastrophically. Caveat emptor.

The Saylors

So either something has changed with savox's qc or they have a flaw in their production line either way i just had another one fail. The inner and outer portion of the output gear now spin free from each other so the bonding process between the two surfaces must have failed. It lasted minutes in a little 2wd slash -.- On top of it, savox is making it extra difficult on returning it. Its too bad, i have always used their servos but three failures in two months is a joke especially with the lack of follow through on the companies end. Oh well futaba and hitech it is i guess.

GRALLONSON

That's what you get when you put a $30 servo on a $300+ plane. Spend the extra money, get the better result.

Propworn

My Feedback: (3)

Maybe a 20 dollar receiver contributed?????? It amazes me that a 300 dollar plus model and someone nickels and dimes the last and only control electronics connecting pilot and model. I'm sorry but the only thing I used Hobby Klunk stuff for was a few indoor foamies and due to the failure rate I stopped using their products all together. Hope it was only the servo not the receiver so it doesn't compromise the next model you put it in. Its not unusual that servos/electronics sustain damage in any crash which makes it very difficult to troubleshoot the failure point after the fact.

Dennis