Neville's Bearhawk

Aircraft testing

After the engine run yesterday the RPM required calibration, and the prop wasn't changing pitch.

Fixing the RPM turned out to be easy and was simply changing a numerical factor in the Tachometer menu.

We didn't have the same luck with the prop. I removed the governor and discovered that it had been fitted correctly, so I reinstalled it. Next we removed the prop to ensure there were no plastic caps in the shaft etc. Again, it was fine. No rags or caps, and the O ring was where it should be and undamaged. There was plenty of oil in the engine crankshaft, although surprisingly little oil in the prop hub. So we re mounted the prop and gave the engine another run. I could only get 1700 RPM before the tires started to slide, and the prop lever was having no effect at all.

After discussing the issue with several engineers, tomorrow we will tether the aircraft and take the RPM to 2300 RPM, and cycle the prop again. Apparently it's not uncommon for the first one or two cycles to require a higher RPM. We also have to check the full power RPM in accordance with the engine overhauled instructions so I'll do that at the same time.

There were still a few instrument calibration errors that I'm working my way through. In the photo below the battery voltage is highlighted in red. I think that may also be the trigger for the ACM fault so I've raised the upper limit to 15.0v before it registers a warning. Not sure about the ALT FAIL light. From memory it's connected directly to the alternator fault wire.

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Full power test