Tuesday, August 9, 2011

Fixing Ultra Micro Servo Problem

A problem I came across while flying my Parkzone Ultra Micro P51 RC airplane was that of a failed aileron servo. While flying the servo just locked up and the plane fell from the sky. At first the problem was intermittent, the servo would work and then just stall. Finally it locked up all together and I thought I would have to replace it.

Parkzone Ultra Micro P51 Servo

Spektrum AS2000 Linear Servo

After doing some research, I found that other UM P51 owners had the same problem and fixed it by lubricating the screw assembly of the servo. From experience with RC helicopters, I know that it's not a good Idea to oil plastic parts. It might be a temporary fix, but in the long run, the oil will attract more dirt and cause an even bigger problem.

I found that by taking the end of my Xacto knife and carefully rotating the Screw Gear, I could get the servo to re-center and start to move again. It was still locking up each time I tried moving the ailerons, so I was pretty sure the problem was a small partial of dirt getting caught in the screw assembly and locking up the works. I broke out a blow gun and attached it to my compressor along with a small length of tubing that I attached to the nozzle of the blow gun. I then blasted air into screw assembly on either side of the linear slide all the while using my radio to move the slide back and forth. Each time the servo would lock, I could take the Xacto to the Screw gear and get it going again. After a minute or so of this, I was able to dislodge what ever was causing the problem and the servo has been operating fine ever since. This is not the cure all of servo repair, but is worth a try before going to the expense of replacing your servo.

If you think this might be your problem, but don't have an air compressor, no worry. You can buy a can of compressed air at your local office supply store. Typically sold for cleaning computer components, they come with a little spray tube nozzle that will work perfectly for cleaning your servo so you can get back in the air quickly.

Tags: Ultra Micro P51, Radio Control, RC, Airplane

1 comment:

  1. I experienced the same thing in my T-28. I tried the compressed air first, but after no luck, I lubricated using Liquid Wrench, a dry lubricant. I share your hesitance to use a liquid lubricant - it will attract dirt. But the dry lube worked great and is plastic safe. Thanks!