It was a strange feeling removing the existing fixed pitch propeller from JONL. After all, it has propelled JONL and its self loading freight for over 200 hours of fun flying. It's an interesting question what to do with it - I think I will keep it, in case it ever becomes necessary to revert.
Anyway, it was simple enough to remove the old prop and I took the opportunity to give the flange and surrounding metalwork a good clean. I paid particular attention to the hollow power shaft, as this has to provide a good hydraulic fluid seal at each end for the prop pitch control system.
Fitting the propeller came next. Firstly the spinner flange was attached to the propeller. It was then necessary to install six bushes in the power flange. These bushes provide two functions: firstly they ensure extremely accurate registration of the propeller as the bushes interlock with milled recesses in the propeller faceplate. They also reduce the size of the hole in the engine power flange to the correct dimensions for the captive propeller bolts. They were a very tight fit in the power flange! It took several attempts to get them all fully home, assisted by a little lubricant.
The prop fitted easily and perfectly on the power flange, engaging with the six bushes, which held it firmly in place whilst the prop nylock nuts and washers were attached. The nuts were torqued up to the required tightness and there we were, propeller installed!
Received wisdom is that the way to do this is using an empty sealant cartridge as an oil reservoir. The applicator is a perfect fit in the filler hole and it provides a small head of oil pressure to help drive out the air. It's also generally agreed that it helps to lift the nose of the aircraft so as to get a greater head, so I did that as well.
I poured a small amount of hydraulic oil into the cartridge and watched with satisfaction as it slowly drained into the system. More oil! Now, exercising the electro-hydraulic pump the oil gradually filled the hydraulic pipe and started running into the pump. It took a while but eventually all the air had bubbled out and the system was full of hydraulic fluid. Removing the cartridge reservoir without getting oil all over the prop was a challenge. I was only partly successful!
It works! In manual mode I was able to adjust the propeller pitch from the Flybox controller, demonstrating the range from fully fine to fully coarse. It seems like such a simple thing but it is the culmination of several months of planning and quite a lot of engineering work, so it was extremely satisfying.
Not a bad note to end 2012 on. Happy New Year to all my followers and see you in 2013 for an update on the flight trials!