Prop Controller Failure

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 On our way back from Oshkosh we experienced a prop controller failure. Three blinking red lights, which according to the documentation indicates "Slipring Brush Worn Out". This had to happen at the worst possible time just as we were arriving at Wendover airport (KENV) which is at an altitude of 4200 feet and was reporting 45C. 

I can't remember the exact density altitude, but it was definitely greater than 8000 feet. Luckily we had some intermittent manual control and we were able to get the prop into a position where we could continue to fly, keeping a close eye on the engine RPM, making sure not to overspeed it. 

After refueling we departed using RW08 (10000'), and we were able gain altitude without any trouble. But during the climb out, to add insult to injury, the GTN650 decided to overheat and report a "Cooling Fan Failure". Luckily that cleared up as we got into higher and (slightly) colder air.

Back in KPAO I emailed Airmaster in New Zealand. We got a quick response from their support team and received a trouble shooting guide. Using this guide and continuity tester, we quickly located the problem; one of the brushes had a broken wire. That seems kind of and early failure after only 250 hours.


We got a new set of brushes from Airmaster, which took a week to arrive, and installed them using the instructions they provide. That was quite easy; you basically clean the solder of the original connection, and solder in the new brush, leaving enough room for the spring to extend.




After reinstalling the brush assembly and testing the prop controls, it all appears to be back in good working order. Problem solved.


Comments

  1. AnonymousSeptember 11, 2022 at 12:04 PM

    This (3 flashing reds) also happened to me at 330hrs. I needed to reboot (toggle the prop control switch until it settled), made it to AMO. First they replaced brushes but it didn't solve the problem, so a be unit was installed.

    ReplyDelete

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