RV-12 First Start
As we all know all builders are not alike. I separate them in to 2 groups – those who’s props do not fly off and disintegrate on first start and those that . . . well, have a rough day, as they say. I am now very proud to be among the first group. I say that now that the event is over, but I did have some reservations leading up to it. For one thing, although I had been very careful to make sure all bolts, nuts etc. had been properly torqued to the specified settings, I could not help but wonder if somehow I had forgotten to do that – even though I had painted torque seal on all the bolts. The night before I had visions of the prop lurching and wobbling until it departed the plane in a spectacular fashion sending shrapnel in all directions. Fortunately that did not happen.
It was about 5:30 in the evening and I was waiting for Marv Scott to arrive at my hanger. I’m at Auburn (S50) and Marv flew in with his RV-4. Once he got parked I rolled out my plane and put down the chocks. I had tested the breaks before but in keeping with my overly cautious mentality I attached the plane to the trailer hitch of my truck with some 500 lb. cinch straps. After it was all secured, Marv and I went over the process and procedures for first start. After completing that, we headed to the plane. I had invited my Friend Doug (RV-6 builder) to come by and witness the event and he in turn invited his brother in law Tim who had built an RV 10, and in a previous life was a Northwest 747 captain. Tim showed up first so he was on point for fire suppression and general observation. My wife Kathy was tasked with recording the event and, in the event of disaster, calling 911.
With the team in place Marv and I hopped into Juliette Kilo and closed the canopy. I opened the POH and went through the startup procedure. With a healthy amount of trepidation I turned the key. The starter engaged and the prop made about half a turn . . . then BAM! the engine roared to life. My only experience to this point had been running either Lycoming or Continental engines and this certainly didn’t sound or feel like either. It ran very smoothly and had quite a different sound than I was used to. The plan was for a 2 minute run. We actually let it run just a bit longer and then went through the shutdown procedure. Throttle to idle, first mag off then second mag and . . . BAM! the engine halted like someone had stuck an iron bar in the prop. Apparently that’s just how the Rotax 912 ULS gently ceases operating. A bit unnerving if you have not witnessed it before. I turned off the master and hopped out to look and see what may have fallen off or leaked. To my great relief everything was still there and no leaks were noticed. I drained out about 4 oz. of fuel from the gascolator to check for floaters. If there were any my eyes could not see them. Marv said “looks good, lets go again” so we hopped back in, went through the startup checklist again and turned the key. It started right up and we ran it until it reached the green on all the temps - maybe 5 or 6 minutes and then shut it down. We hopped back out and checked again for leaks and loose stuff. Everything looked good. A drop or 2 of oil on the ground and just a bit on one of the hoses but we determined it was leftover from the oil purge I had done 2 days before. After a few minutes, Marv suggested I turn the prop until the oil reservoir burped and then check the oil. I did so and it was just a bit low. Added maybe 1/5 of a liter and it was topped off. We started the engine one more time and this time once it was up to temp did run ups to 4000 rpm and checked the mags. All good. Let it run for maybe 8 or 9 minutes and then called it good.
We followed up the engine run with a compression/valve test prescribed by Rotax. The test involved removing the valve cover and the spark plugs from each cylinder. Once removed you put your finger over the hole and moving the prop until you feel the compression. Peak compression indicates the cylinder is lined up to top dead center. With that done, we went through the process of determining if the valve actuators were aligned properly and had sufficient hydraulic pressure. To do this, you push the end of a mallet against the lifter and put about 15 lbs of force on it and see if it moves or feels mushy. You want to maintain a gap of I think .02 (sorry don’t have that number in front of me). We checked each cylinder and all the valve actuators were firm and properly gapped. Word to the wise, let the engine cool way down before you do this.
Well that’s the story to this point. My paperwork to the MIDO has been accepted and I have contacted Charlie Cotton (DAR) and will soon be looking to make this thing legal. Big thanks to Marv Scott who’s been there at every stage of the build and special thanks to friends Doug and Tim who came by at the end of a very long day to help out with the big event.
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