Daily Archives: 09/08/2019

Battery, Engine, Placards & Labels, Propellor

Friday 9th August 2019 – Adjusting the Prop

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With the aircraft substantially complete and awaiting Ian to return to carry out some sign-offs I’m finishing off some smaller jobs that I can do whilst I wait. This includes adding a few more placards and labels, some more taxiing to check nose wheel alignment and brake operation, a couple of engine runs to check its operation and allow me to run to maximum RPM so I can set the fine pitch stop on the Airmaster prop. I’ve also purchased a battery charger for for the Shorai Lithium Iron Phosphate battery that I’ve fitted that balances the cells and ensures a better operation. The upside to this is that it comes with a special lead that fits to the centre port of the battery and not the usual batter terminal. This allows it to be permanently fitted.

The Bristell kit comes with G405 stick grips but I wanted to put the autopilot disconnect and autopilot level buttons on the grip. so I have installed G407 grips instead. It comes with a variety of labels to identify the button function.
The Rotax 912 ULS can run on a variety of fuels but unless you placard them a refuelled may not fill with the option you request. I got the MOGAS sticker from the LAA and Chris Knight from Maypole had a few of the AVGAS UL91 and 100LL stickers.
As the special battery charge lead plugs into the centre port I had to move the battery slightly off centre by moving the packing but was an easier option than re-siting the battery retaining strap.
I’ve run the charge lead to the oil inspection hatch which will allow me to charge the battery or keep it in maintenance mode without taking the top engine cowl off. Quite a neat solution.
One of the things I needed to do was set the Airmaster fine pitch. This involves putting the prop in manual mode and throttling up to just under maximum RPM at 5700. Once this is done then the engine can be shut down and the adjustment made.
Took this just to record some sensor readings at max RPM. Oil temp is a little high which may be because I’ve been stationary whilst running the engine at high RPM. I will be checking that…
Now I’ve set the prop pitch so the engine peaks at 5700 I can set the fine pitch cam. The pitch motor cover is removed to reveal the microswitches and cam adjusters…
The locking nut is undone and the cam adjuster is turned until you hear the microswitch operate and that’s it – very simple.
All that’s required is to reassemble the pitch motor cover and now the fine pitch has been set I can wire lock the screws to make sure that it doesn’t loosen whilst in operation.

I must admit the more I work with the Airmaster prop the more I’m impressed with the quality and engineering. It’s brilliantly simple and well worth the extra I paid. It will be good to see what the performance when it finally flies but from what I’ve seen so far has impressed me. I can virtually guarantee maximum RPM for takeoff and tune the prop for climb and cruise. The fact that it has a 2000 hour TBO to match the Rotax and it’s user maintainable at 100 hours intervals means it will be very cost effective over the coming years.