efish

My Feedback: (5)

Hi, I lost a plane this weekend past either to someone turning on his radio on the same frequency or to a servo that died.

I'm just wondering if there's anyway to tell if a servo is about to die. I have a reasonably thorough pre-flight but I'm just wondering if I'm missing something. A while ago, I saved a plane when I noticed that the elevator was moving really slowly on the pre-flight just before take off; the servo died for good minutes later. So my current checks include:-

1. Sudden "Dead band" or free play in a particular travel position indicating worn/broken tooth or teeth

2. Buzzing or humming (dying motor?)

3. Twitching (indicating dirty pots?)

4. Inability to hold deflection under moderate load

5. Slow/lethargic response

What else am I missing? Is there anyway to assess the condition/response of servos?

Thanks.

dirtybird

My Feedback: (5)

If you come up with a reliable way to predict a failure of any electronic device please come and see me. We will make fortune together.

bruce88123

I find a plume of smoke or the odor of charcoal very indicitive.

efish

My Feedback: (5)

OK, ok ... guess that's one reason we pay more for the big name brand servos - reliability and testing.

Based on info from a friend who was there, it seems that my plane was downed by someone who turned on his transmitter without checking!! If I was a little younger, I think I might have cheerfully beaten the bugger to a pulp!

Thanks anyhow.

onewasp

both, or is it each----dirtybird and bruce88123 have given you the real answer.

However, there is a rule of thumb I use ------ ANY and I mean ANY unusual change in a servo's performance and it is gone from either ailerons or elevator.

"The rest of the story". That procedure I adopted back in "Reed Days".
I have had only ONE servo failure in flight. That was on a new servo, during a maiden flight. A Bonner Transmite with a resin joint-------guess why I remember!!

In todays equipment I have not even had a hint of a failure. The only two things you can check for are pot wear (won't cause a flight failure) or excessive current draw (motor).

If you aren't aware of those two factors in routine practice then you really aren't really "with it" as the high drain servo will show in pack performance while the wearing pot is readily discernible in less than precise maneuvers.

Some of the 3D stuff (no I'm not an advocate) with ganged servos, lousy linkage and wild throws will indeed stall and fry a servo or two---------(perhaps this is the application of Darwin's theory to RC flying--